2014 年 72 巻 8 号 p. 929-939
The Michael/Mannich cascade reaction between acrylate and chiral sulfinimines progressed smoothly by the presence of magnesium thiolate to give optically active β-amino-α-methylthio esters in good yields. The enantioselectivity at the adjacent carbon to the amino group was almost perfect. This procedure was useful for not only aromatic imines but also aliphatic imines. The following oxidation of the phenylthio group and thermal treatment afforded chiral β-amino-α-methylene esters, which were regarded as a potentially useful synthetic building block. Thus, the present method provides a practically useful alternative reaction to the asymmetric aza-Morita-Baylis-Hillman reaction. N-allylated or N-propargylated adducts were examined to the RCM reaction, the Pauson-Khand reaction, and gold(I) catalyzed cyclization. An asymmetric synthesis of (−)-trachelanthamidine was demonstrated. The N-propargylated adducts underwent a cascade radical reaction by treatment with Bu3SnH, Me2S2 and (Me3Si)3SiH, with which radical addition-cyclization-substitution reaction occurred in one step in a highly stereoselective manner. The bicyclic stannolanes, which was prepared by the radical cascade triggered by tin radical, underwent a regioselective double Stille coupling reaction to give multicyclic heterocyclic compounds in good yields.