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STEREOCHEMISTRY OF 2,5-DI-tert-BUTYL- 7-. BUTYROLACTONE-4-CARBOXY-S-(u)-PHENYLETHYLAMIDE. 1. V. Vystorop, A. B. Zolotoi, V. M. Anisimov,.
AUTOASSEMBLY OF CAGE STRUCTURES. 4.* STEREOCHEMISTRY OF 2,5-DI-tert-BUTYL- 7BUTYROLACTONE-4-CARBOXY-S-(u)-PHENYLETHYLAMIDE 1. V. Vystorop, A. B. Zolotoi, V. M. Anisimov, V. G. Kartsev, and R. G. Kostyanovskii

UDC 541.63:542.9t:547.461.5:548.737

The diastereoisomeric tactonamides (2a, b), obtained from the dilactone (1) and S-phenylethylamine, have been s~Tarated. X-ray co,stallography shows that the high-me#ing isomer (2a) has the R-configuration at the chiral centers C2 and 6"4, the enantiomeric conformation of the T-lactone ring being of the S-type in the twist jbrm, intermediate between envelope 2E and semi-chair 23T. It is shown by molecular mechanics that the minimum steric energy qf 2a corresponds to a conformation of the hetemcycle close to the envelopeJbrm 3E. Examination qf van der Waals interactions shows that the calculated ~rructum.for 2a is preferred. The reasonsfor the nonidentity qf the.fbrms of the T-lactone ring of 2a in the co,stal and the free state are discussed. The crystal structure of 2a is composed of m,o geometrically similar independent molecules associated along the axis by weak hydrogen bonds of nvo t3~es, the olergies of which have been estimated from the vXH values, which are related by the expression vXH = f(Rx...o), where, X = N, O. Keywords: diastereoisomeric lactonamides, stereochemisto,, x-ray crystallography, absoluze configura,qon, enaauiomeric conformations,folding parameters, molecularmechwfics, hydrogen bonds, IH and B C NMR spectrum, 1R and mass spectra. A stereoselective synthesis of d,l-ee,d-dihydroxy-c~,cd-di-tert-butylglutaric acid dilactone (1) has been reported [i]~ and this compound has been resolved into its antipodes [2].t In order to establish the absolute configurations of the enantiomers of I, the diastereoisomerically pure iactorlamides (2a, b) have been obtained, and the stereochemistry of the higher-mehing isomer 2a examined. C Me 3

P~

H~~ H~

H ~ C - NHCO

~8)-,z-pE A PhMe A

C Me~

(l)

f/

t/ tO 7 . n _,/l ~,:~

u''n~M%C~ 0 H

(2a)

--t,, ~o~["le

,~H~ % / t ~ ~ z (2b)

The reaction of I with S-c~-PEA (under conditions of thermodynamic control) results, as with BnNH 2 [ l l, in the cleavage of only one of the 3,-lactone rings (followed by PMR by boiling in toluene-d8), but under more severe conditions as a result of increased steric hindrance also stereosetectively (in the first step) with respect to 2a. The c/s- and pseudo-a orientation of the functional substituents in 2a and 2b, favoring secondary, cyclization, was confirmed by the 3Jc7 HI (5.6 and 5.6) and 4JHlrt3 values (1.2 and t.3 Hz) (of. [1]). The R configuration of the chiral centers C 2 and C a in 2a was established by x-ray crystallography in coordinates of the asymmetric center C 14 of the (S)-oe-phenylethylamide group.

*'For previous communication~ see [ 11. tDetails will be reported later. N, N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, t 17977 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 7, pp. 1601-1611, July, 1992. Original article submitted August 9, 1991. 1063-5211/92/4 I07-1235512.50 © 1993 Plenum Publishing Corporation

I235

{36

[1t

Fig. I. Molecule A l , with 50% probability ellipsoids of thermal vibration of the nonhydrogen atoms. T A B L E 1, Coordinates of Atoms in Independent Molecules A 1 and A 2 ( x 10 4) A~

At.m"a X 0 i

Oz Os 0~ N Ct Cz Cs C~ Cs Ce C~ Cs C9 CtO

CII Cl:: CtS Cl5 Cte Ct7 CIs Ct~ C~e Cz~ HI H ~ Ha H ¢ H~ He*

I~I7 *

* Hg *

Ha

[-.It 0 *

-8849(3) -775t(4) -6t40(4) -8647 (4) -8372 (4) -7900(5) -7078(5) -8OO2(5) -8900(5) -6367 (6) -10409(6) -8652(5) -7376(8) -5696(8) -5380(7) - 10772 (7) - 10656(7) -11285(7) -7940(5) -7193(7) -9033 (5) -8919(7) -9869(t0) -10915(8) -11072(6) -10119(6) -8517 (43) -7560(47) -6297 (45) -8561 (50) -7369(56) -8078 -9765, -11675 -11916 -I0221 ~

A~

Y -591 (1) -986 (2) -687 (2) -65(2) 452 (2) -931 (2) -1t80(2) - 1t95

(2)

-677 (2) -t8t5(2) -870 (3) -63(2) -2333(3) -2027 (3) -17t8(3) -1~30(3) -t070(3) -3OO (4) t033(2) 1445(3) 1405 (2) 1643(3) 2032(3) 2t5t (3) 1916(3) 1536(3) - t647 (20) -~068(23) -454(21) 449(23) 9O0(27) 1537 2224 2446 2023 1343

"Z

X

Y

Z

-4566(1) -5435 (2) -4161 (2) -2792(2) -3800(2) -4814(2) -4236(2) -3636 (2) -3809(2) -4375(3) -3705(3) -3442 (2) -4597 (4) -37t0(4) -4960 (4) -4t64(3) -2943(3) -3899(4) -3462 (3) -3968 (3) -3t5t(3) -2467(3) -2202(4) -2563(4) -3234(4) -35f7(3) -365 t (22) -3171 (25) -3780(23) -4230(25) -3038(30) -2167 - 1687 -2348 -3525 -4030

-6123(3) -5643(4) -62O4(3) -6920(4) -8092 (4) -56O5 (4) -5124(5) -4888(5) -58O9(5) -399t (5) -5254(6) -7026(5) -2932(6) -3454(7) -4420(7) -4156 (7) -4774 (8) -6337 (8) -9t82(5) -10000(7) -9963(5) -10640(7) - t t389 (8) - t 1482 (8) -to~o5(9) -10050(7) -3990(43) -5097 (45) -63t0 (42) -8092(51) -8666 (58) - 10559 - 11930 -12057 - 10878 -9505

-604(2) 26(2) 744(2) -6t8(2) -436(2) -73(2) 351 (2) -12t(2) -679(2) 784(3) -t363(3) -573(2) 383(4) t092(4) 1308(3) -t462(3) -1479(4) 1852(3) -229(3) 239(3) -787 (3) - 697 (4) -1t87(5) -t752(5) -1848(4) -i~o(3) -300 (~t) 40(21) 787 (20) -318(23) -82(26) -243 -11.23 -2~34 -2303 - t429

-2t39(2) -3026(2) - t690 (2) -327 (2) -1266(2) -2396(3) -1830(2) -1252(2) -1395(2) -2028(3) -t323(3) =967 (2) -2353(4)

-

- t35t

(4)

-2527 (3) -t840(4) -566(4) -1476(4) -869(3) - 1270(3) -593(3) 28(3) 282 (4) -3O(6) -668(6) -910(4) - 1345(22) -785 (22) -13o9(23) - 169t

(26)

-390(3o) 299 752 t86 -950 -t380

*Fixed coordinate. X-ray examination o f 2a showed the presence o f two independent molecules A 1 (Fig. I) and A 2 with similar geometrical parameters (Tables 1 and 2) (see scheme below). The parameters of the lactone and araide groups in A 1 and A 2 are in agreement with those reported for "y-lactones [3-5], carboxylic acids [6], and N-methylamides [7]. The observed nonequivalence of the exo- (wO ~CtO 2 < o~C2CIO2) and endocyclic valence angles (~oC10t C 4 > ~oC2C 10 I) and bond lengths O t - - C 1 and O 1 _ C a (A = 0. t 5-0.17 A) is also typical o f 7-1actones in the crystal [3-5]. The shortening of bonds O l - - C l and N - - C 7 , and the lengthening of C 1= 0 2, C 7 = 04, O 1__C 4 ' and N - - C 14

1236

....

0 0~'2~ H~H ~ ~I ~zzo

t'%u',,,l

~.~s

[,,,

0

~1 ~.~r

,,

X PR

~.~

A~

~Zrih-'-~';- qla8 ~ v ~ , '

~'~,~ 0

,.~)."

_

Am

H

,~l

o

iZO,a °'**";(5"7~.*~"

C~.Ne

.

in relation to the sums of the atomic covalent radii [81 is, for the most part, due to n--~-* conjugative effects. The t r a n s orientation of bonds N--H 4 and C7 = 0 4 [0(O4C7NH4) = --165.9 ° (At) ] (Table 2) is characteristic of N-methylamides, as a result of stabilization of the crystal structure by intermolecular chain-type hydrogen bonds (IMHB), [7l. The greatest interest resides in the conformation of the heterocycle in 2a in the crystal. According to reported x-ray [3, 4], NMR [4, 91, and molecular mechanical calculations (MM) [9, 101, the great majority of T-lactones possess conformations close to the enantiomeric 3E and/or 3E envelopes with angle r o < +5 °, with C 3 standing out substantially (r 2 = r 3 = 30 °) from the plane of ring OIC1(O2)C 2.

aE ( P = 18°, "Co=0): .~,E( P = 198 °, "r0=0) : N- type ('t'a>0) S-type ('rz