CHINOIN Pharmaceutical Co.

Irbesartan (2-butyl-3-{[2'-(2H-tetrazol-5-yl)biphenyl-4-yl]methyl}-1,3-diaaspiro[4.4]non-1-en-4-one, C₂₅H₂₈-N₆O), a highly selective angiotensin II receptor (AT₁) antagonist was found to exist in two distinct crystal forms (A and B).This paper describes the crystal structure of irbesartan form B.Crystallog. data are given.

Trimethylsilyl N-(4-bromophenyl)carbamate, C₁₀H₁₄BrNO₂Si, and trimethylsilyl N-tert-butyl-N-phenylcarbamate, C₁₄H₂₃NO₂Si, are both important silylating agent.The structures of both mols. are dominated by a plane containing a remarkably large number of atoms.The planes are organized by delocalization around the carbamate moiety.A quasi-pentacoordination of the Si atom in both compounds is also described.Crystallog. data and at. coordinates are given.

The crystal structure of (20R,22RS)-27-norcholest-5-en-3β,20,22-triol 3,22-diacetate, C₃₀H₄₈O₅, is reported.Crystallog. data and at. coordinates are given.