NOVEL PROTECTIVE GROUP IN BETA-LACTAM CHEMISTRY - -PHENYL-N-[ALPHA-(PHENYLTHIO)BENZYL]AZETIDIN-2-ONE

phenyl-1-[phenyl(phenylthio)methyl]azetidin-2-one, C28H23NO2S, with a novel protective group, was prepared from thiophenol. The single-cryst al analysis of the compound reveals the Il atoms at C2 and C3 of the b eta-lactam ring to be in a cis configuration. The relative configurati on at the C2, C3 and C10 chiral centres are established as S, R and R, respectively. The phenoxy and phenyl substituents at C2 and C3 are at an angle of 120.6 (3)degrees with respect to one another, while the b enzyl and thlophenyl rings attached to the N atom of the beta-lactam r ing are at an angle of 4.3 (2)degrees with respect to one another. The central beta-lactam ring is bent, with a mean torsion-angle value of 4.3 (2)degrees.