AN ENANTIOSELECTIVE SYNTHESIS OF (+)-BOSTRYCIN LEADING TO A REVISION OF THE ABSOLUTE-CONFIGURATION OF ITS NATURAL ANTIPODE

An asymmetric Diels-Alder reaction, involving the protected naphthopurpurin (4) and the D-glucose-derived diene (9a), is used to assemble compound (22), which is transformed by way of compounds (26), (27) and (28) into (+)-bostrycin (3). An X-ray analysis of compound (28) confirms that (+)-bostrycin possesses the stereostructure (3) and, therefore, that (-)-bostrycin is its antipode, i.e. (2). The use of naphthazarin (14a) and juglone (14c) as dienophiles in the Diels-Alder reaction enables the synthesis of (+)-demethoxybostrycin (12a) and (+)-demethoxy-5-deoxybostrycin (12b) to be effected. © 1990.