Asymmetric aza-Michael addition: synthesis of (−)-allosedridine and (−)-2-epi-ethylnorlobelol
摘要:
The combination of cross-metathesis and aza-Michael addition is an efficient method for generating piperidine alkaloids. Allosedridine and 2-epi-ethylnorlobelol were synthesized in six steps with ca. 25% overall yield. The aza-Michael addition is reversible for phenyl and alkyl ketones; however, the epimerization is not observed for the corresponding ester and amide. (c) 2008 Elsevier Ltd. All rights reserved.
Asymmetric aza-Michael addition: synthesis of (−)-allosedridine and (−)-2-epi-ethylnorlobelol
作者:Li-Ju Chen、Duen-Ren Hou
DOI:10.1016/j.tetasy.2008.02.019
日期:2008.4
The combination of cross-metathesis and aza-Michael addition is an efficient method for generating piperidine alkaloids. Allosedridine and 2-epi-ethylnorlobelol were synthesized in six steps with ca. 25% overall yield. The aza-Michael addition is reversible for phenyl and alkyl ketones; however, the epimerization is not observed for the corresponding ester and amide. (c) 2008 Elsevier Ltd. All rights reserved.
Synthesis of 2-Substituted Nitrogen Heterocycles Using <i>para</i>-Toluenesulfonyl Iodide in a Key Step
作者:D. Craig、G. Edwards、C. Muldoon
DOI:10.1055/s-1997-1057
日期:——
N-Protected aminoalkenes undergo radical addition of tosyl iodide to give β-iodosulfones which can subsequently be induced to cyclise giving 2-substituted pyrrolidines and piperidines. Incorporation of an α-methylbenzyl group at nitrogen leads to a diastereoselective ring closure where the constituent diastereoisomers can be separated readily giving chiral, non-racemic heterocycles.