The First Example of Polymer-Supported Palladium Catalyst for Stereo

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LETTER

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The First Example of Polymer-Supported Palladium Catalyst for Stereoselective S–S Bond Addition to Terminal Alkynes Polymer-Sup ortedPaladiumCat lystforSter osel ctiveS–SBondAd iton P. Ananikov,*a Michael A. Kabeshov,a,b Irina P. Beletskaya*b Valentine a

Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, Moscow, 119991, Russia Fax +7(95)1355328; E-mail: [email protected] b Lomonosov Moscow State University, Chemistry Department, Vorob’evy gory, Moscow, 119899, Russia Fax +7(95)9393618; E-mail: [email protected] Received 21 January 2005

Abstract: The polymer-supported recyclable palladium catalyst was prepared for stereoselective diaryl disulphides addition to terminal alkynes with high yields. The 96–98% product purity was achieved after filtering the polymer-supported catalyst without special purification procedure.

Pd2dba3 + Ar2S2

R 1

R

PPh3 140 °C, 2 h, toluene

ArS

SAr 2 94–99% isolated yield

Key words: palladium complexes, polymer-supported, catalysis, vinyl sulphides

Scheme 1

Currently the major efforts in academic research and industry are directed to the development of environmentally friendly synthetic procedures.1 Using polymer-supported catalysts offers a great advantage over traditional methods, since it avoids contamination with toxic transition metal complexes and ligands. Additionally, attractive properties of the polymer-supported technology include easy product purification and catalyst recycling.2

purity of the compounds was established with 1H NMR, C NMR and elemental analysis. Z-Configuration of the double bond was determined with 2D NOESY experiment. Therefore, none of the special purification procedures was needed in contrast to the traditional method, which requires chromatography to remove catalyst and ligand.3,5

Catalytic Ar2S2 addition to terminal alkynes has been discovered by A. Ogawa, N. Sonoda et al.3,4 The reaction is catalyzed by palladium complexes and requires an excess of the PPh3 ligand (Pd/PPh3 = 1:10).5 The products of the addition reaction are of high practical interest in organic chemistry6,7 and materials science.8,9 The mechanism of this catalytic reaction has been extensively studied and proceeds via: 1) oxidative addition of S–S bond to Pd(0); 2) alkyne insertion into the Pd–S bond; and 3) C–S reductive elimination.3–5 In the present communication we describe the first example of the Ar2S2 addition to terminal alkynes utilizing polymer-supported palladium catalyst. The developed methodology has important practical advantages deserving special note. We have found that Pd(0) on the triphenylphosphine resin10 is an efficient catalyst for stereoselective Ar2S2 addition to terminal alkynes (Scheme 1).11 The scope of the reaction has been studied for different alkynes (Table 1).12 The polymer-supported catalyst was not sensitive to organic functional groups, in all cases high quantitative yields were obtained. The 96–98% product purity was achieved after filtering the polymer-supported catalyst and removing the solvent (entries 1–8, Table 1). The SYNLETT 2005, No. 6, pp 1015–101706.04205 Advanced online publication: 23.03.2005 DOI: 10.1055/s-2005-865195; Art ID: G03305ST © Georg Thieme Verlag Stuttgart · New York

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Polymer-supported technology provides an excellent opportunity for catalyst recycling (Table 2). At the first cycle Pd2dba3 was adsorbed on the triphenylphosphine resin and used as a catalyst. After the reaction was complete, the polymer catalyst was filtered, washed with toluene and used for the next addition reaction without noticeable loss of activity and stereoselectivity. We have tested Pd2dba3, PdCl2, Pd(OAc)2 and Ni[P(OPh)3]4 as catalyst precursors for adsorption on the polymer. The best results were obtained with Pd2dba3, namely the NMR determined yield of the Ph2S2 addition to heptyne-1 was 99% and stereoselectivity Z/E > 99:1. With PdCl2 and Ni(P(OPh)3)4 only traces of the product were observed ( 99:1) leading to Z-(PhSe)CH=C(SePh)R (3, selenium analog of the compound 2). However, the compound 3 was formed with lower yield of 60–70% (cf. Table 1) and about 30–40% of the Ph2Se was obtained as a by-product. The recycled catalyst was not active in this case.

1016 Table 1 No 1

LETTER

V. P. Ananikov et al. Scope of the Catalytic Ar2S2 Addition to Alkynes Catalyzed by the Polymer-Supported Palladium Catalyst12 R

Product

Isolated yield (%)

-nC5H11 1A PhS

2

-CH2CH2OH 1B

3

-CH2NMe2 1C

2D

99

2E

99

2F

99

2G

98

2H

99

2I

95

2J

94

SPh

-nC4H9 1E SPh-Me-p

-CH2OMe 1F

OMe PhS

-SiMe3 1G

8

-CH2CH2CH2CN 1H

SPh SiMe3

PhS

SPh

CN PhS

SPh

-CH2SPh 1I

SPh PhS

10

99

OH

7

9

2C

SPh

p-Me-PhS

6

95

SPh

-CH2OH 1D PhS

5

2B

NMe2 PhS

4

94

SPh OH

PhS

2A

SPh

-CH2SePh 1J

SePh PhS

SPh

This indicates that the following side-reaction takes place under the catalytic conditions:

Table 2

Catalyst Recycling in Ph2S2 Addition to Heptyne-1 (1-A)13

PPh3 + Ph2Se2 → Se=PPh3 + Ph2Se

Cycle

NMR yield of 2-A (%)

This reaction consumes Ph2Se2 and decreases the yield of product 3. It also consumes the ligand (PPh3) and deactivates the catalyst, since Se=PPh3 is an inferior ligand compared to PPh3. The same process could also take place with Ph2S2. However, the rate of the PPh3 oxidation with sulfur is much lower compared to selenium, since Ph2S was not observed under the catalytic conditions.

1

99

2

99

3

99

Synlett 2005, No. 6, 1015–1017

© Thieme Stuttgart · New York

In summary, the present article describes the first example of S–S bond addition to terminal alkynes catalyzed by the polymer-supported palladium complexes. The high yields and stereoselectivity were observed for various alkynes. Easy product isolation and catalyst recycling are important advantages of the developed catalytic reaction.

LETTER

Polymer-Supported Palladium Catalyst for Stereoselective S–S Bond Addition

Acknowledgment The work was carried out with partial support by President of Russian Federation (Grant for Young Scientists MD-2384.2004.3), the Russian Federation of Basic Research (Project No.04-0332501) and the Chemistry and Material Science Branch of the Russian Academy of Sciences (Program: ‘Theoretical and experimental investigations of the nature of chemical bonding and mechanisms of the most important chemical reactions and processes’).

References (1) (a) Anastas, P. T.; Kirchhoff, M. M. Acc. Chem. Res. 2002, 35, 686. (b) Trost, B. M. Acc. Chem. Res. 2002, 35, 695. (c) Wulff, G. Chem. Rev. 2002, 102, 1. (d) Bergbreiter, D. E. Chem. Rev. 2002, 102, 3345. (e) Anastas, P. T.; Kirchhoff, M. M.; Williamson, T. C. Appl. Catal. A. 2001, 221, 3. (2) (a) Benaglia, M.; Puglisi, A.; Cozzi, F. Chem. Rev. 2003, 103, 3401. (b) Leadbeater, N. E.; Marco, M. Chem. Rev. 2002, 102, 3217. (c) Gilbertson, S. R.; Yamada, S. Tetrahedron Lett. 2004, 45, 3917. (3) (a) Kuniyasu, H.; Ogawa, A.; Miyazaki, S.-I.; Ryu, I.; Kambe, N.; Sonoda, N. J. Am. Chem. Soc. 1991, 113, 9796. (b) Ogawa, A. J. Organomet. Chem. 2000, 611, 463. (4) For general reviews on the catalytic E-E bond addition to alkynes see: (a) Catalytic Heterofunctionalization; Togni, A.; Grutzmacher, H., Eds.; Wiley-VCH: Weinheim, 2001. (b) Beletskaya, I.; Moberg, C. Chem. Rev. 1999, 99, 3435. (5) (a) Ananikov, V. P.; Kabeshov, M. A.; Beletskaya, I. P.; Aleksandrov, G. G.; Eremenko, I. L. J. Organomet. Chem. 2003, 687, 451. (b) Ananikov, V. P.; Beletskaya, I. P.; Aleksandrov, G. G.; Eremenko, I. L. Organometallics 2003, 22, 1414. (c) Ananikov, V. P.; Beletskaya, I. P. Org. Biomol. Chem. 2004, 2, 284. (6) (a) The Chemistry of Organic Selenium and Tellurium Compounds, Vol. 1-2; Patai, S.; Rappoport, Z., Eds.; John Wiley and Sons: New York, 1986. (b) Kondo, T.; Mitsudo, T. Chem. Rev. 2000, 100, 3205. (c) Zyk, N. V.; Beloglazkina, E. K.; Belova, M. A.; Dubinina, N. S. Russ. Chem. Rev. 2003, 72, 769. (7) Hope, E. G.; Levason, W. Coord. Chem. Rev. 1993, 122, 109. (8) Clemenson, P. I. Coord. Chem. Rev. 1990, 106, 171. (9) Lauterbach, C.; Fabian, J. Eur. J. Inorg. Chem. 1999, 1995. (10) The triphenylphosphine resin 100–200 mesh, 1% DVB, 1–1.5 mmol/g was used as a polymeric ligand (ACROS organics, catalog No 35833). (11) Catalyst Preparation. The Ar2S2 (0.2 mmol), PPh3 resin (0.069 mmol, 1.25 mmol PPh3/g, 0.055 g), Pd2dba3 (3.4 × 10–3 mmol, 3 mg), and 0.5 mL of degassed toluene were stirred at 140 °C for 30 min in a sealed tube. The mixture was cooled to the r.t., polymersupported catalyst was filtered and washed thrice with 2 mL of degassed toluene (all manipulations were performed under argon). The formation of polymer-supported

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palladium catalyst is accompanied with releasing free dba ligand (confirmed by NMR). Washing with toluene removes dba from the catalyst. The presence of Ar2S2 on the catalyst preparation stage is important, since oxidative addition of Ar2S2 converts Pd(0) to Pd(II), which is more stable and easier to handle. (12) General Synthetic Procedure. The Ar2S2 (0.3 mmol), the alkyne (0.45 mmol) and 1 mL of degassed toluene were combined with the polymersupported catalyst and the mixture was stirred at 140 °C for 2 h in a sealed tube. The solution was separated and the polymer-supported catalyst was washed twice with 2 mL of degassed toluene. Combined organic solution was evaporated and dried under reduced pressure. The 2A-2H products (96–98% purity) were obtained as yellow oil. Unreacted alkyne was removed with a solvent upon evaporation. Otherwise (for 2I and 2J) flash chromatography was needed to separate unreacted alkynes. The products 2A-2G were identified according to the published NMR data (see ref. 3,5). The data for the 2-H, 2-I and 2-J is given below. Z-CH(SPh)=C(SPh)-CH2CH2CH2CN (2-H): yellow oil. 1H NMR (500 MHz, CDCl3): d = 1.78–1.85 (m, 2 H, CH2), 2.27 (t, 2 H, CH2), 2.40 (t, 2 H, CH2), 6.68 (s, 1 H, HC=), 7.20– 7.38 (m, 8 H, Ph), 7.40–7.45 (m, 2 H, Ph) ppm. 13C{1H} NMR (126 MHz, CDCl3): d = 15.9, 23.9, 35.2, 119.1 (CN), 127.1, 127.2, 129.1, 129.2, 130.0, 130.2, 130.5, 132.4 (HC=), 132.9, 135.0 ppm. MS (EI): m/e (%) = 311 (60) [M+]. Anal. Calcd for C18H17NS2: C, 69.41; H, 5.50; N, 4.50. Found: C, 69.35; H, 5.80; N, 4.40. Z-HC(SPh)=C(SPh)-CH2SPh (2-I): yellow oil. 1H NMR (500 MHz, CDCl3): d = 3.65 (s, 2 H, CH2), 6.70 (s, 1 H, HC=), 7.13–7.17 (m, 2 H, Ph), 7.20–7.33 (m, 11 H, Ph), 7.35–7.39 (m, 2 H, Ph) ppm. 13C{1H} NMR (126 MHz, CDCl3): d = 41.3 (CH2), 126.8, 127.0, 127.1, 127.4, 128.9, 129.0, 129.1, 129.8, 130.7, 131.1, 133.1, 134.1 (HC=), 135.0, 135.1 ppm. MS (EI): m/e (%) = 366 (20) [M+]. Anal. Calcd for C21H18S3: C, 68.81; H, 4.95; S, 26.24. Found: C, 68.90; H, 5.00; S, 26.50. Z-HC(SPh)=C(SPh)-CH2SePh (2-J): yellow oil. 1H NMR (500 MHz, CDCl3): d = 3.68 (s, 2 H, CH2), 6.48 (s, 1 H, HC=), 7.13–7.17 (m, 2 H, Ph), 7.20–7.35 (m, 9 H, Ph), 7.38– 7.42 (m, 2 H, Ph), 7.48–7.52 (m, 2 H, Ph) ppm. 13C{1H} NMR (126 MHz, CDCl3): d = 35.2 (CH2), 127.0, 127.1, 127.7, 128.6, 128.9, 129.0, 129.1, 129.6, 129.9, 130.6, 133.2, 133.3, 134.6, 135.0 ppm. MS (EI): m/e (%) = 414 (70) [M+]. Anal. Calcd for C21H18S2Se: C, 61.00; H, 4.39; S, 15.51; Se, 19.10. Found: C, 60.81; H, 4.33; S, 15.56; Se, 19.10. (13) Catalyst Recycling. After washing with toluene (see general synthetic procedure12) the polymer-supported catalyst can be used in further reactions without additional treatment. When recycling, all manipulations with the catalyst should be performed under argon.

Synlett 2005, No. 6, 1015–1017

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