Marsh, Richard E.Schaefer, William P.Widdowson, Katherine L.Myers, Andrew2009-07-151992Marsh, Richard E., William P. Schaefer, Katherine L. Widdowson, and Andrew G. Myers. 1992. Structure of an anti-aldol addition product of benzaldehyde and a pseudoephedrine-derived O-silyl ketene N,O-acetal. Acta Crystallographica Section C: Crystal Structure Communications C48: 1948-19510108-2701http://nrs.harvard.edu/urn-3:HUL.InstRepos:3190377[4S-(4R*,5R*,8R*,9S*)]-2,2,5,6,8-Penta- methyl-4,9-diphenyl- 1,3-dioxa-6-aza-2-silacyclono-nan-7-one, CE2H29NO3Si, Mr = 383.56, monoclinic, P21, a = 6.550 (3), b = 17.318 (6), c = 20.129 (6) A, /3=98.83(3)° , V =2256.2(14) A 3, Z=4, Dx= 1.13 gcm -3, A(Mo Ka) = 0.71073 A,/z = 1.18 cm -1, F(000) = 824, room temperature, R on F = 0.039 for 4305 reflections with Fo 2 > 3cr(Fo2). The two independent molecules in this structure have nearly the same configuration and geometry. The Si atoms are tetrahedrally coordinated, with average Si--C bond distances of 1.842(3)/~ and average Si---O bond distances of 1.636 (7)A; angles at Si differ from 109.5 ° by an average of 3.5 °. The nine-membered rings are fully extended and the planes of the phenyl groups are approximately perpendicular to the nine- membered ring.en-USJournal Article10.1107/S0108270192002233