Crystal and molecular structure of a synthetic compound related to the penicillins and cephalosporins, 3-benzyl 7-t-butyl 2,2-dimethyl-8-oxo-4-thia-1-aza-6αH-bicyclo[4.2.0]octane-3β,7α-dicarboxylate

Abstract

An intermediate obtained by Lowe and Ramsay in the synthesis of a homopenicillin has been shown by X-ray analysis to have a structure including a β-lactam ring fused to a thiomorpholine ring carrying 2,2-dimethyl and 3-benzyloxycarbonyl substituents. The compound crystallises in the space group P2₁/c, with Z= 4 in the unit cell of dimensions a= 19·160, b= 6·369, c= 19·052 Å, β= 111·59°. The crystal structure was solved from diffractometer data by the symbolic addition method and refined to an R value of 5·16% for 2697 independent reflections by iterative block-diagonal least-squares procedures. The central six-membered ring exists in a distorted chair form and is oriented at 140·8° to the fused β-lactam ring.