title: Organocatalytic asymmetric Michael addition of aliphatic aldehydes to indolylnitroalkenes: access to contiguous stereogenic tryptamine precursors.
abstract: Because of the importance of the indole framework and the versatile transformation of nitro and formyl groups, the efficient synthesis of optically pure 2-alkyl-3-(1H-indol-3-yl)-4-nitrobutanals, one type of tryptamine precursors are of great interest for pharmaceutical and biological research. Herein, the Michael addition of aliphatic aldehydes to indolylnitroalkenes has been developed using (S)-diphenylprolinol trimethylsilyl ether as an organocatalyst, which provides the desired optically pure syn 2-alkyl-3-(1H-indol-3-yl)-4-nitrobutanal derivatives in up to 98% yield with up to >99:1 dr and >99% ee. To show the synthetic usefulness of this methodology, optically active 2-alkyl-4-nitro-3-(1-tosyl-1H-indol-3-yl)butan-1-ol and tryptamine derivatives are readily obtained by stepwise systematic transformations.
authors: Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People's Republic of China.
authors: Jian
authors: J
authors: Chen
authors: Zhi-Cong
authors: ZC
authors: Geng
authors: Ning
authors: N
authors: Li
authors: Xiao-Fei
authors: XF
authors: Huang
authors: Feng-Feng
authors: FF
authors: Pan
authors: Xing-Wang
authors: XW
authors: Wang
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D002384:Catalysis; D005227:Fatty Acids / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry*; D015394:Molecular Structure; D009574:Nitro Compounds / Q000737:chemistry*; D013237:Stereoisomerism; D014363:Tryptamines / Q000737:chemistry*
chemical_list: D000447:Aldehydes; D005227:Fatty Acids; D007211:Indoles; D009574:Nitro Compounds; D014363:Tryptamines; C030820:tryptamine