Application of new optically pure ketene equivalents derived from tartaric acids to the total, asymmetric syntheses of (+)-6-deoxycastanospermine and (+)-6-deoxy-6-fluorocastanospermine

Abstract

Condensation of di-O-acetyl-(S,S)-tartaric anhydride with the diethyl acetal of. N-ethylaminoacetaldehyde gave (1S, 5S, 7S)-3-ethyl-2-oxo-6, 8-dioxa-3-azabicyclo[3.2.1]octane-7-carboxylic acid (8) whose 1-cyanovinyl ester (10) added to furan to give, after two recrystallizations, an optically pure 7-oxabicyclo[2.2.1]hept-5-en-2-yl derivative (11) that was converted into (+)-6-deoxycastanospermine (+)-(2) and (+)-6-deoxy-6-fluorocastanospermine (+)-(3).