Asymmetric total synthesis of (-)-alkaloid 223A and its 6-epimer.
The enantiopure gamma-amino alcohols 7 and 18 are prepared by using the diastereoselective Michael addition of lithium N-benzyl (R)-alpha-methylbenzylamide to alpha,beta-unsaturated esters as a key step. The Michael addition of 7 or 18 to an alkynone 8 followed by an intramolecular cyclization afford the cyclic enamine 10 or 20, which are subjected to the diastereoselective hydrogenation, and the subsequent transformations provide 6-epi-alkaloid 223A and alkaloid 223A, respectively.
Pu
Xiaotao
X
State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, China.
Ma
Dawei
D
D000470:Alkaloids / Q000138:chemical synthesis*; D000818:Animals; D001001:Anura; D002384:Catalysis; D020650:Combinatorial Chemistry Techniques; D007202:Indicators and Reagents; D007212:Indolizines / Q000138:chemical synthesis*; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D013237:Stereoisomerism
C104548:6,8-diethyl-5-propylindolizidine; D000470:Alkaloids; D007202:Indicators and Reagents; D007212:Indolizines