Total Synthesis of (−)-Belactosin C and Derivatives via Double Diastereoselective Tandem Mukaiyama Aldol Lactonizations

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 β-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.