Synthesis of a New Amino Acid-Antibiotic, Oxetin and Its Three Stereoisomers.

Oxetin (1a), a unique antibiotic having an oxetane ring, and its three stereoisomers (1b, 1c, and 1d) were synthesized from the known aldehyde (6) by utilizing a highly regio- and stereoselective epoxide ring-opening reaction. The biological activities of these oxetin stereoisomers were compared.