Asymmetric synthesis of piperidines using the nitro-Mannich reaction☆
2021
Anderson, James C. | Bouvier-Israel, Eva | Rundell, Christopher D. | Zhang, Xiangyu
A method for the synthesis of functionalized piperidines containing 3 contiguous stereocentres in the 2-,3- and 4- positions uses a diastereoselective nitro-Mannich to control stereochemistry. The nitro-Mannich reaction between a β-aryl/heteroaryl substituted nitroalkanes and glyoxylate imine provides β-nitro-amines with good selectivity (70:30 to >95:5) for the syn, anti-diastereoisomers. Reductive cyclisation with BF₃.OEt₂ and Et₃SiH gave, after purification, stereochemically pure piperidines in 19–57% yield for ten examples with different 4-aryl/heteroaryl substituents.
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