Structures of two diastereomers of the tetrahydrobenzothiophene moiety of breynolide.
(1) (+/-)-3-Triisopropylsiloxy-2,3,3a,7a-tetrahydrobenzo[b]thiophen -5(4H)-one 1,1-dioxide, C17H30O4SSi, Mr = 358.57, triclinic, P1, a = 7.4383 (14), b = 8.1000 (15), c = 16.895 (3) A, alpha = 80.202 (14), beta = 88.800 (15), gamma = 76.231 (14) degrees, V = 974.0 (3) A3, Z = 2, Dx = 1.22 g cm-3, Mo K alpha, lambda = 0.7107 A, mu = 2.339 cm-1, F(000) = 388, T = 298 K, R = 0.0436 for 3086 reflections [F0 greater than or equal to 4 sigma(F0)]. (2) (+/-)-3-tert-Butyldiphenylsiloxy-2,3,3a,7a-tetrahydrobenzo[b]th iophen- 5(4H)-one 1,1-dioxide, C24H28O4SSi, Mr = 440.63, triclinic, P1, a = 9.113 (2), b = 11.020 (2), c = 12.551 (3) A, alpha = 74.01 (2), beta = 70.83 (2), gamma = 88.70 (2) degrees, V = 1141.4 (4) A3, Z = 2, Dx = 1.28 g cm-3, Mo K alpha, lambda = 0.7107 A, mu = 2.125 cm-1, F(000) = 468, T = 298 K, R = 0.0424 for 4262 reflections [F0 greater than or equal to 4 sigma(F0)]. The two rings are cis-fused with the cyclohexenone ring in the sofa conformation and the tetrahydrothiophene ring in the half-chair conformation for both (1) and (2). However, the bulky siloxy groups assume different orientations in the two compounds. In (1), the triisopropylsiloxy group is equatorial and close intramolecular contacts between H2A and H4B [2.29 (3) A], O11 and C4 [2.934 (3) A] and O9 and C7 [2.979 (3) A] are observed.(ABSTRACT TRUNCATED AT 250 WORDS)
Lynch
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VM
Department of Chemistry, University of Texas, Austin 78712.
Daniel
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D
Martin
S F
SF
Davis
B E
BE
D055598:Chemical Phenomena; D002627:Chemistry, Physical; D015394:Molecular Structure; D017646:Organosilicon Compounds; D013237:Stereoisomerism; D013876:Thiophenes; D014961:X-Ray Diffraction
D017646:Organosilicon Compounds; D013876:Thiophenes; C064476:3-triisopropylsiloxy-2,3,3a,7a-tetrahydrobenzo(b)thiophen-5(4H)-one 1,1-dioxide; C064477:3-tert-butyldiphenylsiloxy-2,3,3a,7a-tetrahydrobenzo(b)thiophen-5(4H)-one 1,1-dioxide