Synthesis and X-Ray Crystal Structure of (-)-Calicheamicinone

摘要

Diels-Alder reaction between ketene acetal 3 and the #beta#-nitroacrylate ester 12 of (-)-8-phenylmenthol gave optically pure ketone 17. This substance was modified in such a way as to remove the chiral auxiliary and afford the epimeric silyl ethers 20M and 20m. Following procedures worked out using racemic materials, both 20M and 20m were converted into optically pure (-)-calicheamicinone (1). This is a crystalline substance, and an X-ray structure determination was carried out.