Journal of the American Chemical Society, Vol.141, No.21, 8527-8540, 2019
Total Synthesis of Caprazamycin A: Practical and Scalable Synthesis of syn-beta-Hydroxyamino Acids and Introduction of a Fatty Acid Side Chain to 1,4-Diazepanone
The first total synthesis of caprazamycin A (1), a representative liponucleoside antibiotic, is described. Diastereoselective aldol reactions of aldehydes 12 and 25-27, derived from uridine, with diethyl isocyanomalonate 13 and phenylcarbamate 21 were investigated using thiourea catalysts 14 or bases to synthesize syn-beta-hydroxyamino acid derivatives. The 1,4-diazepanone core of 1 was constructed using a Mitsunobu reaction, and the fatty acid side chain was introduced using a stepwise sequence based on model studies. Notably, global deprotection was realized using palladium black and formic acid without hydrogenating the olefin in the uridine unit.