Enantioselective synthesis of 2-substituted-N-Boc-Δ-4,5-piperidines
摘要:
The title compounds were prepared through a synthetic sequence involving: (i) a reaction of the condensation product between an enantiopure beta -amino alcohol and an aldehyde with allylmagnesium chloride; (ii) an N-allylation of the resulting secondary amine; (iii) a chemoselective cleavage of the beta -amino alcohol residue; and (iv) a protection of the secondary amine followed by a ring closing metathesis. The advantageous use of (1R,2S)-norephedrine was demonstrated in these syntheses. (C) 2001 Elsevier Science Ltd. All rights reserved.
Enantioselective synthesis of 2-substituted-N-Boc-Δ-4,5-piperidines
摘要:
The title compounds were prepared through a synthetic sequence involving: (i) a reaction of the condensation product between an enantiopure beta -amino alcohol and an aldehyde with allylmagnesium chloride; (ii) an N-allylation of the resulting secondary amine; (iii) a chemoselective cleavage of the beta -amino alcohol residue; and (iv) a protection of the secondary amine followed by a ring closing metathesis. The advantageous use of (1R,2S)-norephedrine was demonstrated in these syntheses. (C) 2001 Elsevier Science Ltd. All rights reserved.
A new phosphoramiditeligand was used in the iridium-catalyzed allylicsubstitution reaction. This permitted high regio- and enantioselectivities on a wide variety of substrates and nucleophiles. Because of the stereospecificity of the reaction obtained by using branched substrates, a kinetic resolution reaction was attempted. The origin of the impressive efficiency of this ligand in terms of kinetics