Unified Total Syntheses of Fawcettimine Class Alkaloids: Fawcettimine, Fawcettidine, Lycoflexine, and Lycoposerramine B
作者:Guojun Pan、Robert M. Williams
DOI:10.1021/jo3006045
日期:2012.5.18
syntheses of the lycopodiumalkaloids fawcettimine, fawcettidine, lycoflexine, and lycoposerramine B have been accomplished through an efficient, unified, and stereocontrolled strategy that relies on a Diels–Alder reaction to construct the cis-fused 6,5-carbocycles with one all-carbon quaternary center. Access to the enantioselective syntheses of both antipodes of those alkaloids can be achieved by
Enantioselective vinylogous Mukaiyama aldol reaction of α-ketoesters under bifunctional organocatalysis
作者:Roberto del Río-Rodríguez、Víctor Laina-Martín、Jose A. Fernández-Salas、José Alemán
DOI:10.1039/d1cc04263g
日期:——
A highly enantioselective vinylogous Mukaiyama aldol reaction to ketoesters catalysed by a hydrogen-bond-donor-based bifunctional organocatalyst is presented. The addition of silyloxy dienol ether gives rise to multifunctional chiral tertiary alcohols bearing a versatile α,β-unsaturatedaldehyde with excellent enantiocontrol.
The reactivity and the regioselectivefunctionalization of silyl-diene enol ethers under a bifunctional organocatalyst provokes a dramatic change in the regioselectivity, from the 1,5- to the 1,3-functionalization. This variation makes possible the 1,3-addition of silyl-dienol ethers to nitroalkenes, giving access to the synthesis of tri- and tetrasubstituted double bonds in Rauhut-Currier type products