651053-80-4Relevant articles and documents
Efficient Solution-Phase Parallel Synthesis of 4-Substituted N-Protected Piperidines
Wang, Xiaoyang,Kauppi, Anna M.,Olsson, Roger,Almqvist, Fredrik
, p. 4586 - 4592 (2007/10/03)
Practical conditions for the synthesis of 4-substituted N-protected piperidines through CuCN·2LiBr-catalyzed organozinc additions to 1-acylpyridinium salts and subsequent hydrogen-transfer hydrogenation have been established. The reaction sequence is performed at room temperature and provides 4-substituted N-protected piperidines in excellent overall yields without the isolation of intermediate dihydropyridines, In those cases in which the organozinc addition results in mixtures of 2- and 4-substituted dihydropyridines, the 2-substituted isomers are efficiently scavenged with maleic anhydride and subsequently removed by a mild extractive workup with NaHCO3 (sat.). The N-acyl group can conveniently be exchanged from N-phenoxycarbonyl to N-tBoc, thus allowing orthogonal deprotection strategies. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.