Selective rearrangement of terminal epoxides into methylketones ...

Electronic Supplementary Material (ESI) for Chemical Communications. This journal is © The Royal Society of Chemistry 2014

Supporting Information

Selective rearrangement of terminal epoxides into methylketones catalysed by a nucleophilic rhodium-NHC-pincer complex Eva Jürgens,a Barbara Wucher,a Frank Rominger,b Karl W. Törnroos,c Doris Kunza* a

Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, D-72076 Tübingen (Germany)

b

Institut für Organische Chemie, Heidelberg University Im Neuenheimer Feld 250, D-69120 Heidelberg (Germany)

c

Department of Chemistry, University of Bergen, Allégaten 41, 5007 Bergen (Norway)

Contents 1. 2. 3. 4. 5.

Experimental procedures and analytical data Crystallographic details for compounds 4a and 4b 1 H and 13C NMR spectra of the new compounds IR spectra of 1 and 2a Catalytic epoxide rearrangement: optimisation of the reaction conditions regarding additive and solvent 6. References

S2 S17 S19 S31 S33 S33

1.

Experimental procedures and analytical data

General Procedures. Unless otherwise noted, all reactions were carried out under an argon atmosphere in dried and degassed solvents using Schlenk techniques. Acetonitrile and thf were purchased from Sigma Aldrich, dried, and degassed using an MBraun SPS-800 solvent purification system. All lithium and sodium salts used were obtained from commercial suppliers, dried in vacuum and used without further purification. Epoxides were obtained from commercial suppliers and degassed under vacuum prior to use. The rhodium complex 1 was synthesised according to the literature procedure.[1] 1H and 13C NMR spectra were recorded using a Bruker ARX 250 and AVANCE II +400 spectrometer. 1H and 13C chemical shifts are reported in ppm and calibrated to TMS on the basis of the residual solvent proton signal as an internal standard (1.73 ppm, thf-d8; 1.94 ppm, CD3CN; 5.32 ppm, dichloromethane-d2). Assignment of peaks was made using 2D NMR correlation spectra. IR spectra were recorded on a Bruker Vertex70 instrument. The mass spectrum was recorded on a Thermo Finnigan TSQ 70.

Synthesis of rhodium complex 1:

We already reported the synthesis of this compound.[1] Additional 1H NMR data of compound 1 in thf-d8 and C6D6: 1

H NMR (thf-d8, 400.11 MHz): δ = 1.55 (s, 18H, t-Bu), 4.20 (s, 6H, NCH3), 7.45 (d, 3J = 2.0 Hz, 2H, H-4´), 7.82 (d, 4J = 1.8 Hz, 2H, H-2/7), 8.16 (d, 4J = 1.8 Hz, 2H, H-4/5), 8.23 (d, 3J = 2.0 Hz, 2H, H-5´). 1

H NMR (benzene-d6, 400.14 MHz): δ = 1.56 (s, 18H, t-Bu), 3.74 (s, 6H, NCH3), 6.14 (d, 3J = 1.6 Hz, 2H, H-4´), 7.31 (d, 3J = 1.6 Hz, 2H, H-5´), 7.63 (d, 4J = 2.0 Hz, 2H, H-2/7), 8.49 (d, 4J = 2.0 Hz, 2H, H-4/5). 13

C{1H}NMR (benzene-d6, 100.61 MHz): δ = 32.5 (C(CH3)3), 35.0 (C(CH3)3), 40.3 (N-CH3), 110.9 (C2/7), 114.7 (C4/5), 115.7 (C5´), 122.7 (C4´), 125.4 (C1/8), 129.3 (C4a/5a), 37.3 (C1a/8a), 139.2 (C3/6), 182.5 (d, 1JRhC = 45.9 Hz, C2´), 199.8 (d, 1JRhC = 71.4 Hz, CO).

S2

General Procedure for the Meinwald rearrangement with rhodium complex 1:

O 4

6

2 1

3

5

Rh(bimca)CO[1] 1 (2 mg, 4 mol, 10 mol%) and lithium bis(trifluoromethanesulfonimide) (1 mg, 10 mol%) were placed into a J. Young NMR tube and 1,3,5-trimethoxybenzene as internal standard and benzene (0.5 mL) were added. At last dried 1,2-epoxyhexane (4.2 μL, 35 mol) was added and the reaction mixture was heated to 60 °C and monitored via 1H NMR spectroscopy during the time given. 1

H NMR (benzene-d6, 400.11 MHz): δ = 0.77 (t, 3J = 7.4 Hz, 3H, H-6), 1.08 (ps sext, 3J = 7.5 Hz, 2H, H-5), 1.34 (ps quint, 3J = 7.7 Hz, 2H, H-4), 1.64 (s, 3H, H-1), 1.87 (t, 3J = 7.3 Hz, 2H, H-3).


In the glove box, 10 mg 1 (18.5 µmol) and lithium bis(trifluoromethanesulfonimide) (5 mg, 1 eq) were dissolved in 0.5 mL benzene-d6 in a J. Young NMR tube. Propylene oxide (1.5 µL, 1.2 eq) was added to the reaction mixture, which was allowed to react at room temperature for 10 minutes. The resulting species 2 (R1, R2 = CH3) was characterised by NMR and IR spectroscopy in solution. 1

H NMR (benzene-d6, 400.14 MHz): δ = 1.04 (d,3J = 5.8 Hz, 3H, CH3), 1.35 and 1.52 (each s br, each 9H, t-Bu), 3.56–3.63 (m, 1H, CH), 3.69 and 3.85 (each s br, each 3H, NCH3), 6.32 and 6.49 (each s br, each 1H, H-4’, H-9’), 7.11 and 7.45 (each s br, each 1H, H-Carb), 7.16 (from 2D) and 7.49 (each s br, each 1H, H-5’, H-10’), 7.86 and 8.07 (each s br, each 1H, HCarb). The signal at 7.16 ppm is covered by the solvent signal and was assigned via 2D spectra (1H1H-COSY, 1H13C-HMBC, 1H13C-HSQC) as well as the signal for the CH2-group that is covered by the t-Bu-group (1.52 ppm) signals. 1

H NMR (toluene-d8, 400.14 MHz): δ = 1.04 (d,3J = 5.8 Hz, 3H, CH3), 1.31 and 1.51 (each s br, each 9H, t-Bu), 1.37–1.44 (s br, 2H, CH2) 3.56–3.63 (m, 1H, CH), 3.65 and 3.82 (each s br, each 3H, NCH3), 6.26 and 6.49 (each s br, each 1H, H-4’, H-9’), 7.09 and 7.40 (each s br, S3

each 1H, H-Carb), 7.15 and 7.52 (each s br, each 1H, H-5’, H-10’), 7.74 and 7.95 (each s br, each 1H, H-Carb). 13

C{1H} NMR (benzene-d6, 400.14 MHz): δ = 19.1 (CH3), 23.2 (d br, 1JRhC = 23.0 Hz, CH2), 32.0 and 32.2 (C(CH3)3), 34.4 and 34.6 (C(CH3)3), 38.7 and 39.0 (NCH3), 80.5 (s br, CH), 109.6 and 109.9 (CCarb), 114.2 and 114.5 (CCarb), 115.2 and 116.6 (C5´, C10´), 118.5 and 121.7 (C1, C8), 123.4 and 123.7 (C4a, C5a), 124.5 and 124.7 (C4´, C9´), 135.5 (C1a, C8a), 138.2 (C3, C6), 174.1 and 174.5, (each d, each 1JRhC = 56.0 Hz, C2´, C7´), 207.1 (d, 1JRhC = 46.2 Hz, CO). 𝜈̃(benzene-d6, cm-1) = 2046 (vw br, Rh-CO), 1716 (w, acetone), 1645 (w), 1588 (w). (Formation of complex 2 was confirmed by NMR spectroscopy prior to the IR-measurement. Therefore benzene-d6 was used as a solvent.)

In situ generation of type 2 complexes by reaction of 1a/b and epoxides in benzene-d6:

R2 = CH3, C4H9

1 R1 = CH3 (a), C2H5 (b)

2a/b (R1 = CH3, R2 = CH3 (a), C4H9 (b)) 2c/d (R1 = C2H5, R2 = CH3 (c), C4H9 (d))

Other unsymmetrical complexes of type 2 can be generated at room temperature by reacting Rh(I) complexes 1a and 1b with 2 eq of epoxide and 2 eq of LiNTf 2 in benzene-d6. Reaction of complexes [Rh(bimca)(CO)] (1a) or [Rh(bimcaEt)(CO)] (1b) with propylene oxide and 1,2epoxyhexane lead clearly to the respective complexes of type 2, but the amount depends on the steric demand of both reaction partners. Complex 1a (R1 = CH3) reacts with both epoxides at room temperature completely to 2a/b, while 1b (R2 = C2H5) leads to a mixture of 1b and 2c/d.

S4

0.70

Eva340.010.001.1r.esp

2b benzene

0.65

2b 0.60

0.55

0.50

0.45

0.40

2b

0.35

0.30 1,2-epoxyhexane 0.25

1,2-epoxyhexane

0.20

0.15 2b

2b

0.10 2b

2b

0.05

2b

2b

2b

2b

2b

2

0

2a Standard (TMB)

Standard (TMB)

-0.05

propylene oxide

2a propylene oxide

2a 2a

-0.10 2a 2a

2a

2a

2a

2a 2a

1 9.0

8.5

8.0

7.5

7.0

6.5

6.0

5.5

5.0

4.5 4.0 Chemical Shift (ppm)

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

-0.5

Figure 1. Complete conversion of 1a and propylene oxide (1, blue) or 1,2-epoxyhexane (2, green) at room temperature to complexes 2a and 2b. 0.075

Eva344_Zugabe_Propoxid_30min.esp 1b ( -CH 3) and 4d

0.070

1b (-C(CH 3) 3) and 4d

0.065 0.060 0.055 0.050 0.045 0.040 1b

0.035

1b

1b 1b

0.030

1b (N-CH 2-)

epoxyhexane and 2d

0.025 1,2-epoxyhexane

0.020 0.015 0.010 2d

0.005

2d

2d

2d

2d

2d

2d

2 0 -0.005 1b ( -C2H5) and 2c

-0.010 1b

-0.015

1b

-0.020

propylene oxide

2c

1b

1b

1,2-epoxyhexane

1b (N-CH 2-) -0.025 -0.030 2c -0.035

2c

2c2c

8.0

7.5

2c

2c

2c

2c

2c

2c

1 8.5

7.0

6.5

6.0

5.5

5.0

4.5 Chemical Shift (ppm)

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

Figure 2. Reaction of 1b with propylene oxide (1, blue) and 1,2-epoxyhexane (2, green) at room temperature led to the analogue complexes 2c and 2d. In this case the conversion of 1b is incomplete and led to a ratio of 1b:2c = 4:3 or 2d (1b:2d = 8:1).

S5

After full conversion of the epoxide the starting complexes 1a/b are recovered (by NMR spectroscopy). Eva344_Startspektrum.esp 0.40 1b (-C(CH3)3)

Standard (TMB)

+ acetone 0.35

0.30 standard (TMB) 0.25

0.20

0.15 1b -CH2CH3

0.10 C6 D5 H 1b

1b

1b

1b

1b N-CH2-

0.05

0

3 propylene oxide

C6 D5 H propylene oxide -0.05 2c

2c

2c

8.0

7.5

2c

2c

2c

2c

2c

2c

2c

2 -0.10

-0.15

1 8.5

7.0

6.5

6.0

5.5

5.0


3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

-0.5

Figure 3. Monitoring the reaction of 1b with propylene oxide in benzene-d6; spectrum 1 (blue): before addition of propylene oxide, spectrum 2 (green): after addition of 2 eq propylene oxide, and spectrum 3 (grey): after 16 h at room temperature (full conversion of the epoxide to acetone and recovery of complex 1b).


3

Route 1: In the glove box, 15 mg of 1 (26 µmol) were dissolved in 0.5 mL tetrahydrofurane-d8 with propylene oxide (2 µL, 1 eq) and lithium chloride (1 mg, 1 eq) in a J. Young NMR tube. The reaction mixture was allowed to react at room temperature for 4 days, after which the complete formation of 3 was observed. Slow decomposition during workup prevents further analysis. S6

1

H NMR (thf-d8, 400.14 MHz): δ = 1.16 (d,3J = 6.2 Hz, 3H, CH3), 1.50 and 1.51 (each s, each 9H, t-Bu), 1.65–1.75 (m, 2H, CH2), 3.55–3.66 (m, 1H, CH), 3.98 and 3.99 (each s, each 3H, NCH3), 7.21 and 7.22 (each d, each 3J = 2.1 Hz, each 1H, H-4´, H-9´), 7.61 and 7.64 (each d, each 4J = 1.5 Hz, each 1H, H-4, H-5), 7.99 and 8.00 (each d, each 4J = 1.5 Hz, each 1H, H-2, H-7), 8.18 and 8.19 (each d, each 3J = 2.1 Hz, each 1H, H-5´, H-10´). 13

C{1H} NMR (thf-d8,100.61 MHz): δ = 22.3 (CH3), 26.1 (d, 2JRhC = 30.0 Hz, CH2), 32.9 and 32.9 (C(CH3)3), 35.5 (2x C(CH3)3), 39.5 and 39.8 (NCH3), 79.4 (CH), 109.5 and 109.7 (C4, C5), 114.3 and 114.5 (C2, C7), 117.6 and 117.8 (C5´, C10´), 124.6 and 124.8 (C4´, C9´), 125.7 and 126.3 (C4a, C5a), 127.6 and 127.5 (C1, C8), 136.9 and 137.0 (C1a, C8a), 136.9 and 137.0 (C3, C6) 180.5 and 181.0 (each d, each 1JRhC = 41.0 Hz, C2´, C7´), 229.4 (d, 1JRhC = 43.3 Hz, CAcyl). MS (FAB+): m/z = 628.3 (1 %) [M+H]+, 642.3 (100 %) [M-C3H6O2]+.

Route 2: In the glove box, 15 mg of 1 (26 µmol) were dissolved in 0.5 mL acetontirile-d3 with propylene oxide (2 µL, 1 eq) and lithium chloride (1 mg, 1 eq) in a J. Young NMR tube. The reaction mixture was allowed to react at room temperature for 24 h at 60 °C, after which the complete formation of the new species 3 was observed. Slow decomposition during workup prevents further analysis. 1

H NMR (CD3CN, 400.14 MHz): δ = 1.14 (d, 3J = 6.1 Hz, 3H, H-15), 1.51 (s, 18H, t-Bu), 1.56–1.63, 1.64–1.73 (each m, each 1H, CH2), 3.55–3.66 (m, 1H, CH), 3.95 and 3.95 (each s, each 3H, NCH3), 7.23 and 7.24 (each d, each 3J = 2.2 Hz, each 1H, H-4´), 7.68 and 7.70 (each d, each 4J = 1.5 Hz, each 1H, H-4, H-5), 8.07 and 8.08 (each d, each 4J = 1.5 Hz, each 1H, H-2, H-7), 8.18 and 8.20 (each d, each 3J = 2.1 Hz, each 1H, H-5´). 13

C{1H} NMR (CD3CN, 100.61 MHz): δ = 22.4 (CH3), 26.6 (d, 2JRhC = 36.7 Hz, CH2), 30.0 and 32.9 (C(CH3)3), 36.0 (2x C(CH3)3), 40.0 and 40.3 (NCH3), 80.0 (CH), 110.8 (C4, C5), 115.0 and 115.3 (C2, C7), 125.7 and 126.0 (C4´, C9´), 126.2 and 126.7 (C4a, C5a), 127.2 and 127.4 (C1, C8), 136.0 and 136.6 (C1a, C8a), 139.0 (C3, C6) 179.6 and 179.8 (each d, each 3 JRhC = 40.7 Hz, C2´, C7´), 228.8 (CAcyl, no coupling detected due to low intensity). Signals for C5´ and C10´ could not be detected due to overlap with the signal for CD3CN. MS (FAB+): m/z = 628.3 (1 %) [M+H]+, 642.3 (100 %) [M-C3H6O2]+.

S7

Synthesis of rhodium complex 4a:

4a

In the glove box, 15 mg 1 (26 µmol) were dissolved in 0.5 mL thf-d8 with propylene oxide (2 µL, 1 eq) and lithium chloride (1 mg, 1 eq) in a J. Young NMR tube. The reaction mixture was allowed to react at 80 °C for 4 days, after which the formation of yellow precipitate was observed. The solvent was removed and the yellow residue dissolved in CD2Cl2 and characterised NMR spectroscopically. 1

H NMR (CD2Cl2, 400.14 MHz): δ = 1.55 (s, 18H, t-Bu), 2.01 (br s, 3H, CH3), 3.96 (s br, 1H, CH), 4.18 (s, 6H, NCH3), 7.17 (d, 3J = 1.7 Hz, 2H, H-4´), 7.65 (d, 4J = 1.3 Hz, 2H, H-2/7), 8.03 (d, 3J = 1.7 Hz, 2H, H-5´), 8.14 (d, 4J = 1.3 Hz, 2H, H-4/5). 13

C{1H} NMR (thf-d8, 100.61 MHz): δ = 21.0 (CH3), 31.9 (C(CH3)3), 34.7 (C(CH3)3), 38.7 (NCH3), 93.6 (CH), 110.8 (C4´), 114.7 (C2/7), 116.3 (C5´), 125.3 (C4/5), 127.6 (C4a/5a), 135.0 (C1a/8a), 137.2 (C1/8), 139.3 (C3/6), 174.6 (d, 1JRhC = 112.6 Hz, C2´), 189.8 (d, 2JRhC = 89.0 Hz, CORh), the CAcyl signal could not be detected.

The equilibrium between Rh-catalyst 1 and complex 3a in thf-d8: Experiment whether species 3a is able to release acetone and such reacts back to catalyst 1 or complex 3a gets only deactivated by dehydrogenation to 4a (Figures 4-7).

1

3a

4a

Complex 1 was dissolved with a catalytic amount of LiCl and propylene oxide in thf-d8 (Figure 4). After 20 h at room temperature a mixture of 1 and 3a (2:1) and a small amount of Rh complex 4a was obtained. Upon evaporation of the solvent and redissolving the residue in thf-d8, the ratio of complexes 1 to 3a remained unchanged, but all organic components were removed (Figure 5). After 1 day at room temperature acetone was generated and the 1H NMR spectrum shows complex 1 as the only organometallic species (Figure 6). The thf-d8 and all volatiles were evaporated again and the residue dissolved in dichloromethane-d2 (as S8

the solubility of 4a is much better in CD2Cl2). The 1H NMR spectrum gives evidence for the formation of 4a (Figure 7). Thus we could demonstrate that some amount of complex 3a releases acetone under regeneration of 1 as well as it can be dehydrogenated to complex 4a. 1

1

7.5323 6.08417.5275 4

3

3

grease

1.5761

0.1489

1.2588 1.2461

3

4

propyleneoxide

7.5069 7.5019

3

7.6897 7.6501

8.0746

0.090 0.005

7.7733

4

0.0100.095 4

8.0299

3

8.2573 8.2329

0.015

std 1

4.2435

Eva357_1H_Startspektrum.esp

3.7408

7.8592 7.8550

8.2798 8.2747

0.020

8.3549 8.3492

Normalized Intensity

0.025

7.3026 7.2976 7.2808 7.2751

Eva357_1H_Startspektrum.esp 1 1

8.1848 8.1810

0.030

0.085 0 0.15 1.98 0.23 0.22 1.94 0.14 0.44 0.080 0.075

8.25

2.01

8.00

0.15 0.22 0.19

1.92 0.13


0.070

0.19 0.21

7.50

7.25 thf

3.6246

0.065

1.7659

thf

std 0.055 0.050

t-Bu's

0.045

1.5486 1.5369


0.060

0.040 0.035

4.0487 4.0427

4.3227

7.7733 7.6897

7.5069 7.5019 7.3026 7.2976 7.2808 7.2751

8.0746 8.0299

8.3549

0.005

2.8824

3 4

0.015 0.010

2.3062

7.5323 7.5275

0.020

7.8592 7.8550

8.2798 8.2747 8.1810

0.025

2.6205

propyleneoxide 0.030

3

0 0.15 1.98 0.23 0.22 1.94 0.14 0.44 2.01 0.15 0.22 0.19 1.92 0.13 0.19 0.21 8.5

8.0

7.5

7.0

6.5

6.0

0.33 5.85 1.08 5.5

5.0

3.56 3.94


3.5

3.0

2.5

4.04

17.12 2.36 3.96 13.06 0.45 0.67 2.0

1.5

1.0

0.5

0

1

Figure 4. H NMR spectrum recorded directly after the addition of propylene oxide (std = 1,3,5-trimethoxybenzene). Eva357_thf_aufgenommen.esp

7.5347 7.5293 4

0.010

8.2544 8.2490

3

3

7.3046 7.3000 7.2852 7.2798

3 4

7.5067 7.5013

3 4

7.7780 7.7741

0.12

4

8.0741 8.0702 8.0360 8.0251

3

0.13 0.005

grease

std

0.1126

std

1.5396

6.0476

Eva357_thf_aufgenommen.esp

7.6901 7.6863 7.6528 7.6489

7.8580 7.8541

1

3.7042

1

8.1837 8.1798

1

8.2777 8.2723

1 1

8.3570 8.3516


0.015

0.110 0.49 2.93 0.93 0.94 2.75 0.61 1.73 0.10

2.93 0.51 0.98 0.89 2.64 0.44

8.0

1.64

7.5 Chemical Shift (ppm) t-Bu's std

1.5124

1

0.07

thf

3.5892

0.06

1.4999

0.08

4.2039

0.05

thf

1.7300


0.09

0.04 0.03

4.0050 3.8806

3

1.2924 1.1883 1.1727 1.1564 1.1409

4.2825

0.01

8.2417 8.2363 8.1477 8.1438 8.0000 7.8220 7.8181 7.6541 7.6129 7.4987 7.4932 7.4707 7.2686 7.2639 7.2492 7.2437

0.02

3 4

3

0 0.49 2.93 0.93 0.94 2.75 0.62 1.73 2.94 0.51 0.99 0.90 2.64 0.44 1.64 30.04 8.0

7.5

7.0

6.5

6.0

1.40 8.94 5.36 0.67 111.44 0.66 5.5

5.0


3.5

27.36 6.08 17.14 2.05 0.96 2.43 3.0

2.5

2.0

1.5

1.0

0.5

0

1

Figure 5. H NMR spectrum after removing all volatiles in vacuo and redissolving the residue in thf-d8 (std = 1,3,5trimethoxybenzene).

S9

3.7046

Eva357_thf_aufgenommen_1d_rt.esp

std

0.40

0.1117

grease

0.35

6.0476

std


1

1.5390

0.30

0.25

0.20

0.15

1.2919 1.1896 1.1744

3.63

3.5890

acetone

2.0474

3.41

thf

3.5595

7.5034

1

7.8230

8.2458 8.1473

1

4.0464

1 1

0.05

thf

1.7300

4.2082

1 0.10

0 3 3.45 3.47 8.0

30.00

7.5

7.0

6.5

10.58 1.09 115.94 14.13 1.01

6.0

5.5

5.0


3.5

3.0

1.05

45.34

2.0

1.5

2.5

1.51

1.78 1.0

0.5

Figure 6. After 1 day at room temperature only species 1 can be detected and some acetone is produced (std = 1,3,5trimethoxybenzene).

std

grease

std

0.1181

1.5745

1

6.0998

Eva357_2.040.001.1r.esp

0.13 0.12 0.11 1

4.2561

0.10

0.08 dcm

0.07

5.3504


0.09

0.06 0.05

thf

1.8022

1.2995

34

2.0458

thf 3

2.3701

3.9852 3.9567

7.6817 7.5499

4 3

3.6723 3.5963

4.2313

7.3079

3

43

43

8.1828

0.01

4

7.2031

43

1

1

7.7789

8.2173

0.03 0.02

8.0551

3 1 1 1 +4

0.04

0 2.01 3 0.57 2.44 2.00 0.49 0.22 1.92 0.65 8.5

8.0

7.5

7.0

5.27 1.43 0.24 6.5

6.0

5.5

5.0

4.5


0.23 3.0

2.5

0.53 1.10 25.20 1.36 2.0

1.5

1.0

0.5

0

-0.5

1

Figure 7. H NMR spectrum after removing all volatiles and redissolving the residue in CD2Cl2 (std = 1,3,5trimethoxybenzene).

S10

Dehydrogenation of complex 3 to the deactivation product 4:

Dehydrogenation of complex 3 to complex 4 is accompanied by hydrogenation of the acetone (which is formed during the catalysis) to isopropanol (Figure 8).

Eva355_WEand_1Tag_rt.esp

std

0.55

0.50

0.45

0.40

0.35

0.30 Normalised Intensity std

0.25

0.20

0.15 All volatile compunds (epoxide + isopropanol) are removed.

0.10 THF

0.05

0

THF

2 acetone

-0.05

mixture of 1 and 4

epoxide epoxide isopropanol

-0.10 1 8.0

7.5

7.0

6.5

6.0

5.5

5.0

4.5 4.0 3.5 Chemical Shift (ppm)

3.0

2.5

2.0

1.5

1.0

0.5

0

Figure 8. After evaporation of all volatile compounds the signal at 1.08 ppm (isopropanol) is missing (std = 1,3,5trimethoxybenzene).

S11

The equilibrium between 1 and 3 in benzene: Experiment, if complex 3 (generated in thf-d8) also released acetone upon dissolving in benzene-d6. Two independent experiments were carried out. Experiment 1: Complex 1 was dissolved with a catalytic amount of LiCl and propylene oxide in thf-d8. After 16 h at 60 °C a mixture of complexes 1:3 (1:1) and Rh complex 4 was obtained. Upon evaporation of the solvent and redissolving the residue in thf-d8 the ratio of 1 to 3 remained constant, but all volatile components were removed. The thf-d8 is again removed and the residue dissolved in benzene-d6. The 1H NMR spectrum shows 1 as the major organometallic species. As the acetone signal is covered by the t-Bu signal in benzene-d6, a few drops of dmso-d6 were added to shift the acetone peak (Figure 11). The outcome of this experiment gives evidence for the backward reaction of 3 into the catalytic cycle also in benzene. 6.0485

x Eva353.020.001.1r.esp

2

1.5400 1.5130

Aceton

2.0490

x

1a 2

3.7056

Eva353.020.001.1r.esp

2

6.0485

0.005

x

leads to a 1:1 mixture of 1a:2 (60 °C, 16 h)

11a

7.5059

0.010

1a 1

7.3374 7.2794 7.2579

2

7.8204

1a 1 2

7.6538 7.6158

1a1

8.2420 8.2170 8.1435 8.0418 7.9927


Reaction of 1a and LiCl with Propylenoxide 0.015

0 1.74 1.87 0.21 0.48 1.72 1.58 0.10 0.96 0.29 0.69 0.19 1.39 0.41 1.71

1.5007

30.00

0.075 8.0

7.5

0.070


0.065

6.5

6.0

Standard

Standard

0.060 Propyleneoxide thf

0.045

1.7300

3.5909

0.050

1.2232 1.2105

thf

4.2089

1

0.040 0.035 0.030

2

0.025

4.0191 4.0103

0.020

3.78

4.8927 4.8443

x2

2

1.1915 1.1760 1.1573 1.1421

3.05 3.58

2.8361

x

2.2729

7.9927 7.8204 7.6538 7.6158 7.5059 7.3374 7.2794 7.2579

0.005

8.1435

0.010

Propyleneoxide

8.2420

0.015

2.5871


0.055

x

0 2.01 2.16 0.24 0.56 1.99 1.83 2.55 0.47 1.97 8.0

7.5

7.0

0.84 6.5

6.0

5.5

5.88 6.110.77

5.0 4.5 4.0 Chemical Shift (ppm)

1.53 3.5

3.0

2.5

1.67 2.0

13.44 19.53 11.15 1.80 2.78 1.5

1.0

Figure 9. Reaction of catalyst 1 with propylene oxide at 60 °C; after 16 h at room temperature a 1:1 mixture of complexes 1:3 was obtained (Standard = 1,3,5-trimethoxybenzene).

S12

0.025

Eva353.030.001.1r.esp

1 2 3

1

32

32

1a +2 +3

1.5377 1.5108 1.4988

0.005

32

7.8220 7.6703 7.8179 7.6538 7.6152 7.6117 7.5113 7.3510 7.5059 7.3368 7.3320 7.2785 7.2737 7.2604 7.2557

0.010

1

1

8.1445 8.1404 8.0384 7.9921

0.015

8.2471 8.2420 8.2157


0.020

Eva353.030.001.1r.esp

0 2.11 2.25 0.16 2.00 0.35 2.15 2.03 0.99 1.02 2.00 0.10 0.16 2.08

Standard

30.00

0.055 8.0

7.5


6.5

6.0

thf

0.050 1

thf

4.2095

Standard 0.045

0.040


0.035

0.030

0.025

4.0172 4.0096

2 0.020

1.1545 1.1389

1.2907 1.1893

3.6330

3.4785 3.4015

0.005

3 2

4.8934 4.8443

0.010

8.2471 8.2420 8.2008 8.1445 8.1404 8.0384 7.9921 7.8220 7.8179 7.6703 7.6538 7.6117 7.5113 7.3368 7.5059 7.3320 7.2785 7.2737 7.2604 7.2557

0.015

0 2.08 2.22 1.98 0.35 2.12 2.00 0.98 1.01 1.97 0.10 0.16 2.06 8.0

7.5

7.0

0.37

6.5

6.0

5.5

5.78 6.12


2.64 0.45 0.50

4.0

19.31 2.77 19.41 2.73 0.85 3.07

3.5

3.0

2.5

2.0

1.5

1.0

Figure 10. Reaction mixture after removing all volatiles and dissolving the residue in thf-d8 (Standard = 1,3,5trimethoxybenzene).

Eva353.040.001.1r.esp

benzene Benzol

Standard

Eva353.040.001.1r.esp

8.0


6.5

6.0

0.60

1.5365

8.5

0.65

0.10

0.05

0

4.24

0.50

benzene Benzol

9.53

2.94


0.45

1.0

Standard

0.40

6.2541

0.35

Standard

0.30

1 (C(CH3)3 + Aceton

1.5580


21.43 11.50

7.1600

0.55

H grease

H grease

0.9245

30.00 2.55 0.25

1.7110 1.6920

0.70

2.65 0.60


2.39 0.56

1.3543

2.72

6.0495

Eva353.040.001.1r.esp 0

1.5580

6.1597

1

7.3200

7.6339

1

3.3153

1

7.5144

0.025

1

8.4903

0.050

8.4393


0.075

0.25 0.20

0.9245

1.7110 1.6920

6.1597 6.0495

7.3200

1.3543

3.7531

1

1

7.6339 7.5144

0.05

8.4903 8.4393

0.10

1

1

1.5365

1

0.15

0 2.39 0.56 8.5

2.65 0.60 2.72 8.0

7.5

30.00 2.55 0.25 7.0

6.5

6.0

0.26 5.5


6.50 1.23 4.0

3.5

98.64

4.24 21.43 11.50 9.53 2.94 3.0

2.5

2.0

1.5

1.0

0.5

Figure 11. The reaction mixture after removing all volatiles and dissolving of the residue in benzene-d6 (Standard = 1,3,5trimethoxybenzene).

S13

1.8766

Eva353.050.001.1r.esp

0.45

0.40

6.5465

0.35

7.5277 0.25

2.5000

0.20

4.3628

0.15

0.10

0.5447 0.5130

1.1602

1.5507 1.5399

2.3134

4.4540

4.2298

7.5623

8.2502

0.05

8.1413

8.7016 8.6183 8.5480 8.4441

acetone

2.0996


0.30

0 2.39 0.58 0.40 2.27 2.40 0.35 1.99 8.5

8.0

1.46 6.90

7.5

7.0

6.5

6.0

5.5

5.0

2.18 27.31


3.5

3.0

2.5

4.29

2.0

1.50

1.5

6.38

1.0

0.5

0

Figure 12. Addition of dmso-d6 to the solution shifts the acetone signal so that it is not covered by the t-Bu signal.

Experiment 2: Complex 1 is dissolved with a catalytic amount of LiCl and propylene oxide in thf-d8. After 16 h at r.t. a mixture of complexes 1:3a = 1.3:1 was obtained. Upon evaporation of all volatile compounds and dissolving the residue in thf-d8 the ratio of 1:3a remained constant. All volatiles were removed again in vacuo and the residue was dissolved in benzened6. The 1H NMR spectrum of the suspension clearly shows complex 1 as the only organometallic species. Heating the sample for 1 h at 60 °C led to formation of a new Rh complex. Upon removal of benzene-d6 in vacuo and dissolving the residue in CD2Cl2 this species was identified as complex 4a which could have formed from precipitated 3a by dehydrogenation.

8.0

0.11

7.3161 7.2876 3.34

Std


3.7569

3.46 4.43

1+3

7.0

1.5915 1.5643 1.5529 1.2789 1.2580

8.5

4.66

3

6.0998

0 Eva356_16h_rt.esp 4.47 3.45 4.54 3.49

1 3

7.5377

0.025

1 3

7.7063 7.6640

1 3

7.8680

1

8.0461

0.050

8.2943 8.2854 8.2545 8.2014


0.075 Eva356_16h_rt.esp

propylene oxid

4.2589

1 0.10 Std

thf

0.07

thf

0.06 propylene oxid

2.0986

acetone

1.7822

0.08

3.6401


0.09

0.05 3

4.0644

0.04

1.2125 1.1879

7.3161 7.2876

7.7063 7.6640

0.01

7.5377

3

7.8680

0.02

8.0461

8.2943 8.2854 8.2014

0.03

0 4.47 3.45 4.54 3.49 4.66 3.46 4.43 3.34 8.5

8.0

7.5

30.00 7.0

6.5

6.0

13.68 9.61 5.5

5.0


109.31

23.04 26.14 3.5

3.0

2.5

26.79 5.41 2.0

42.13 34.56 88.73 5.57 1.5

1.0

0.5

0

1

Figure 13. H NMR spectrum after 16 h at room temperature in thf-d8 (std = 1,3,5-trimethoxybenzene).

S14

0.40

1

0.2778

1.5393

3.2966

Eva356_benzol.esp

7.1416

Std

0.35

6.2354

benzene

0.30

0.25

thf

0.20 1

3.7327

0.15

1.6085

1.3566

3.8772

1.6932

1

7.7455

8.3145

0.05

1

7.6150

8.4707

1

6.1382

1

7.3002

0.10

1.8999


Std

0 7.74 1.52 8.5

1.89 7.39 8.0

5.43

29.94 5.59

7.5

7.0

6.5

6.0

0.82 17.51 5.5

5.0


97.49 3.5

2.52 7.71 73.24 13.24 3.0

2.5

2.0

1.5

1.0

0.5

1

Eva356_benzo_60l.esp

1.5592

3.3158

Figure 14. H NMR spectrum after removing all volatiles in vacuo and dissolving the residue in benzene-d6 (std = 1,3,5trimethoxybenzene).

1+4

Std

0.2970

0.45

0.40

0.35

6.2537

Std

1

3.7495

7.1600


benzene 0.30

0.25

0.20

4

4

4

1.8608

4

6.1076

7.5144

8.4432

4

1

3.6982

4 0.05

1

4.3169

7.6333

8.4899

1

6.1550

1 0.10

7.3186

0.15

0 10.89 0.72 8.5

10.99 0.67 10.85 8.0

7.5

29.93 9.86 0.40 7.0

6.5

6.0

0.44 5.5

5.0

33.10 2.96 115.47


3.5

1.37 131.64 10.66 3.0

2.5

2.0

1.5

1.0

0.5

1

Figure 15. After heating the suspension for 1 h at 60 °C, the dehydrogenated rhodium species 4 can be detected in the H NMR spectrum (std = 1,3,5-trimethoxybenzene).

S15

0.2852

1.5470

3.3044

Eva356_benzol_benzol.esp

1+4

Std

3.7379

1

6.2415

7.1488

0.30

benzene Std

0.20

0.15

1

1

1

1

7.6195

6.1409

8.4788

0.10

7.3098


0.25

4

1.2962

4

1.8490 1.7932

4

6.8314

4

3.6868

4

7.5034 7.4616

8.4262

4

4.3030

0.05

0 15.45 1.04

15.41 1.27 17.11

8.5

8.0

0.09

7.5

7.0

30.02 14.93 1.72 6.5

0.51

6.0

5.5

5.0

49.93 5.20


118.87

3.5

1.79 1.40 182.93 13.55 3.0

2.5

2.0

1.5

1.0

0.5

1

Figure 16. H NMR spectrum after removing all volatiles in vacuo and dissolving the residue again in benzene-d6 (std = 1,3,5trimethoxybenzene).

Std

0.40

1

0.35

6.0967

4.2554

Std

0.30

0.25

dcm 5.3482


1.5710

3.7771

1+4 Eva356.080.001.1r.esp

0.20

1

thf

1.2945

thf 4

1.7959

4

2.0433

4.3856

7.2015

7.6801

8.1802

4

3.9517

4

4.2326

4 4 0.05

3.6726

1

7.3086

0.10

1

7.7739

8.2132

1

8.0526

0.15

0 14.40 2.27 15.79 13.27 1.81 8.5

8.0

12.84 1.25 7.5

30.02 7.0

6.5

6.0

2.23 35.52 3.55 0.84 5.5


4.0

3.5

3.0

2.5

2.10

161.17

2.0

1.5

1.0

1

Figure 17. H NMR spectrum after removing benzene-d6 and dissolving the residue in dichloromethane-d2 to verify complex 4 by its chemical shift (std = 1,3,5-trimethoxybenzene).

S16

2.

Crystallographic details for compounds 4a and 4b

Crystallographic Data. Data collection was carried out on a Bruker APEX Duo CCD (4b) with an Incoatec IµS Microsource with a Quazar MX mirror, or a Bruker APEX CCD (4a) diffractometer, using Mo Kα radiation (λ = 0.71073 Å) and a graphite monochromator in both cases. Corrections for absorption effects were applied using SADABS.[2] All structures were solved by direct methods using SHELXS and refined using SHELXL.[3] Further details of the refinement and crystallographic data are given in the respective CIF-files. CCDC 1018408 (compound 4a) and 1018409 (compound 4b) contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.

Crystal structure of complex 4a: In the glove box, 15 mg 1 (26 µmol) were dissolved in 0.5 mL thf-d8 with propylene oxide (2 µL, 1 eq) and lithium chloride (1 mg, 1 eq) in a J. Young NMR tube. The reaction mixture was allowed to react at 80 °C for 4 days. Single crystals suitable for X-ray diffraction were obtained from a saturated solution of the reaction mixture at room temperature. The structure contains three thf solvent molecules, two of which are disordered.

S17

Crystal structure of complex 4b: Rh(bimca)CO[1] 1 (2 mg, 4 mol, 10 mol%) and lithium bis(trifluoromethanesulfonimide) (1 mg, 10 mol%) were placed into a J. Young NMR tube and 1,3,5-trimethoxybenzene as internal standard and benzene (0.5 mL) were added. At last dried 1,2-epoxyhexane (4.2 μL, 35 mol) was added and the reaction mixture was heated to 60 °C. Single crystals from pentane/thf, suitable for X-ray diffraction were obtained from a saturated solution of the reaction mixture upon cooling to room temperature. The structure contains a region with heavily disordered solvent molecules. These could be identified from the shape to be a pentane and a thf molecule. The two add up to 144 electrons. The Squeeze procedure[4] in programme package PLATON[5] reports the equivalent of 167 electrons per asymmetric unit, in total 344 electrons. One ordered thf solvent molecule is included in the reported structure. The alkyl product suffers from disorder in all three unique molecules. The current model still suffers from large displacement parameters, in particular at the terminal end of the alkyl product; also the C-C-distances in those regions suffer from large variations.

S18

1

H and 13C NMR spectra of the new compounds

3.

1

Exemplary H NMR spectrum for a Meinwald rearrangement (100 min, 60 °C, 30 mol% LiNTf2, 10 mol% 1, benzene)

1

std

std 3.3023

Eva340_Nachtmessung.010.001.1r.esp

6.2284

H NMR spectrum of 2 in benzene-d6:

0.19 0.18

propyleneoxide

0.17 0.16 0.15

1.5773

0.11

1.5060

acetone

0.12

0.10 0.09

7.1416

0.06 0.05

0.2761

0.07

1.3379

benzene

0.08

propyleneoxide

1.0160

1.9707

2.2909

2.5443

3.8373

6.4755

6.2946

7.0900

0.01

7.4695 7.4337

0.02

8.0469

0.03

3.6808 3.5864

0.04

7.8492


0.13

0.9118 0.8988

0.14

0 2.26 1.85 8.0

4.65 7.5

1.75 7.0

2.00 1.92 6.5

6.39 6.42 2.93 6.0

5.5

5.0


3.5

5.02 3.0

2.5

5.54

5.57 13.43 17.66 18.00 6.44 16.50 2.0

1.5

1.0

0.5

S19

0.02

0.01

208 200 192 184 176 168 160 152 144 136 128 120 112 104 96 Chemical Shift (ppm) 88 80 72 64 56 48 40

24.0165 23.7591 20.6368 18.2027

39.7542 39.4500 35.2932 32

propyleneoxide

32.9433 32.7139 30.5513

55.1877

0.11

24 16

1.7441

0.04

propyleneoxide

std

std

93.8766

0.12

48.4891 48.0303

std

0.13

81.2424

0.05

162.6834

0.06

138.9458 136.2308 125.4456 125.2209 124.3971 124.1536 122.3889 119.2338 117.3053 115.9431 115.2362 114.8992 110.6301 110.3399

175.5282 175.0929 174.9712 174.5592

0.03

acetone

0.16

208.0288 207.5700 207.5373


benzene

13

C{1H} NMR spectrum of 2 in benzene-d6:

Eva340_13C.esp

0.15

0.14

0.10

0.09

0.08

0.07

0 8

1

H NMR spectrum of 3a in thf-d8:

S20

0

13

1

C{ H} NMR spectrum of 3a in thf-d8:

13

C-DEPT-135 NMR spectrum of 3a in thf-d8:

S21

1

13

H C-HSQC NMR spectrum of 3a in thf-d8:

S22

1

13

H C-HMBC NMR spectrum of 3a in thf-d8:

S23

1

H NMR spectrum of 3a in CD3CN:

13

1

C{ H} NMR spectrum of 3a in CD3CN:

S24

13

C-DEPT-135 NMR spectrum of 3a in CD3CN:

1

H1H-COSY NMR spectrum of 3a in CD3CN:

S25

1

13

H C-HSQC NMR spectrum of 3a in CD3CN:

S26

1

13

H C-HMBC NMR spectrum of 3a in CD3CN:

S27

1

H NMR spectrum of 4a in CD2Cl2:

13

1

C{ H} NMR spectrum of 4a in CD2Cl2:

S28

1

13

H C-HSQC NMR spectrum of 4a in CD2Cl2

S29

1

13

H C-HMBC NMR spectrum of 4a in CD2Cl2

S30

4.

IR spectra of 1 and 2a

IR spectrum (benzene-d6) of complex 1.

S31

IR (benzen-d6) of complex 2a.

S32

5. Catalytic epoxide rearrangement: optimisation of the reaction conditions regarding additive and solvent

Table 1 Optimisation of the reaction conditions: additive and solvent.a

Entry

Additive

Solvent

T [°C]

Time [h]

Yieldb,c [%]

1

LiCl

thf-d8

60

24

4

2

NaCl

thf-d8

60

24

2

3

LiCl

CD2Cl2

60

24

0[d]

4

LiCl

CD3CN

60

24

0[d]

5

NaBF4

thf-d8

60

24

13

6

NaBPh4

thf-d8

60

24

45

7

NaBPh4

C6D6

60

24

61

8

LiB(C6F5)3

C6D6

60

24

90

9

LiNTf2

C6D6

60

24

>99

a

Reaction conditions: 1 (10 mol%), additive (10 mol%), all reactions were carried out in a J. Young NMR tube with 1,2-epoxyhexane (35 μmol) as substrate and 0.5 mL solvent. b The ketone was observed as the sole reaction product. c The yield was determined by 1H NMR using 1,3,5-trimethoxybenzene as internal standard. d Catalyst deactivation due to organometallic side products.[6]

6.

References

[1] M. Moser, B. Wucher, F. Rominger, D. Kunz, Organometallics 2007, 26, 1024–1030. [2] G. M. Sheldrick, SADABS 2012/1; University of Göttingen, Göttingen, Germany, 2012. [3] a) G. M. Sheldrick, Acta Cryst. 2008, A64, 112-122; b) C. B. Hübschle, G. M. Sheldrick, B. Dittrich, J. Appl. Cryst. 2011, 44, 1281−1284. [4] SQUEEZE routine: van der Sluis, P.; Spek, A. L. Acta Cryst. 1990, A46, 194-201. [5] PLATON: Spek, A. L. J. Appl. Cryst., 2003, 36, 7-13. [6] In dichloromethane oxidative addition (trans) of the solvent to complex 1 is observed which leads to [Rh(bimca)Cl(CH2Cl)(CO)]. M. Moser, PhD thesis, Heidelberg University, 2007.

S33