Aldecalmycin, a new antimicrobial antibiotic from Streptomyces. III. Determination of absolute configuration

The planar structure of aldecalmycin (1) had been determined in the previous paper, together with the conformations of the substituted trans decalin ring having one double bond and the sugar: beta-glucopyranoside type. The absolute configuration of 1 was a following problem to be solved. X-Ray crystallographic analysis of crystalline 4'-6'-O-benzylidenedihydroaldecalmycin (4) revealed the relative configuration. On the other hand, the stereoisomerism of the sugar was determined to be D by the optical rotation value of tetra-O-acetyl-alpha-methylglucopyranoside derived from 1. These results established the absolute configuration of 1.