Asymmetric total syntheses of ansamacrolactams (+)-Q-1047H-A-A and (+)-Q-1047H-R-A.

The total syntheses of ansamacrolactams (+)-Q-1047H-A-A (16) and (+)-Q-1047H-R-A (17) have been achieved for the first time in 17 steps, leading to the reassignment of the relative stereochemistries and absolute configurations of their natural counterparts. The key steps in the synthetic work included an asymmetric chelation-controlled vinylogous Mukaiyama aldol reaction for the stereoselective synthesis of the syn-aldol adduct 7b and an intramolecular SmI(2)-mediated Reformatsky reaction for the formation of the macrocyclic lactam 14.