Total synthesis of (-)-belactosin C and derivatives via double diastereoselective tandem mukaiyama aldol lactonizations.

[reaction: see text] The enantioselective synthesis of (-)-belactosin C and derivatives was accomplished in a concise manner employing the tandem, Mukaiyama aldol-lactonizaton (TMAL) process. One approach involved a distal double diastereoselective TMAL reaction with a dipeptide glyoxamide, whereas a second approach involved amide coupling of a dipeptide with a beta-lactone carboxylic acid, obtained via the TMAL process employing a chiral silyl ketene acetal. Notable improvements in diastereoselectivity were achieved in a proximal double diastereoselective TMAL process.