Asymmetric Total Synthesis of (-)-Lupinine and (+)-Epilupinine via α-Sulfinyl Ketimine. Stereocontrolled Reduction of β-Sulfinyl Enamines
作者:Duy H. Hua、Shou Wu Miao、Ana A. Bravo、Dolores J. Takemoto
DOI:10.1055/s-1991-26620
日期:——
(-)-Lupinine and (+)-epilupinine [(1R,9aR)- and (1S, 9aR)-octahydro-1-hydroxymethyl-2H-quinolizine] were synthesized from (+)-2,3,4,5-tetrahydro-6-[(R)-(4-methylphenyl)sulfinylmethyl]pyridine (4) in five steps. The intermediate, 3,4,6,7,8,9-hexahydro-1-[(R)-(4-methylphenyl)sulfinyl]-2H-quinolizine (7), was stereoselectively reduced with cerium(III) chloride heptahydrate and sodium borohydride to give predominantly C-9a-R isomers, (9aR)-octahydro-1-[(R)-(4-methylphenyl)sulfinyl]-2H-quinolizines.
(-)-Lupinine 和 (+)-epilupinine [(1R,9aR)- 和 (1S,9aR)-八氢-1-羟甲基-2H-喹嗪]通过五步反应从 (+)-2,3,4,5-四氢-6-[(R)-(4-甲基苯基)亚砜甲基]吡啶 (4) 合成得到。中间体,3,4,6,7,8,9-六氢-1-[(R)-(4-甲基苯基)亚砜]-2H-喹嗪 (7),经铈(III)氯化物七水合物和硼氢化钠选择性还原,主要得到 C-9a-R 异构体,即 (9aR)-八氢-1-[(R)-(4-甲基苯基)亚砜]-2H-喹嗪。