the stereochemistry of HPA-12, an important ceramide-trafficking inhibitor that was discovered and synthesized and its stereochemistry determined in 2001, the synthesis and the stereochemistry were reinvestigated. A large-scale synthetic method for HPA-12 based on a Zn-catalyzed asymmetric Mannich-type reaction in water was developed. Single crystals of HPA-12 for X-ray crystallographic analysis were
A domino Kornblum-DeLaMare/aza-Michael reaction of 3,6-dihydro-1,2-dioxines and application to the synthesis of the ceramide transport inhibitor (±)-HPA-12
作者:Sarah V.A.-M. Legendre、Martyn Jevric、Julian Klepp、Christopher J. Sumby、Ben W. Greatrex
DOI:10.1016/j.tet.2017.11.010
日期:2018.3
A Kornblum-DeLaMare/aza-Michael reaction of 3,6-dihydro-1,2-dioxines with primary and secondary amines has been developed which affords 4-hydroxy-3-aminoketones. The aza-Michael products were reduced using non-selective NaBH4/MeOH or diastereoselective (up to 92:8) SnCl4/NaBH4 conditions yielding (1R*,3S*)-3-amino-1,4-diols in up to 97% and 70% yield respectively. The major reduction product was converted in two steps to (+/-)-HPA-12, which is an inhibitor of the cytosolic ceramide transporting protein. (C) 2017 Elsevier Ltd. All rights reserved.
Ruthenium-Catalyzed Asymmetric <i>N</i>-Demethylative Rearrangement of Isoxazolidines and Its Application in the Asymmetric Total Syntheses of (−)-(1<i>R</i>,3<i>S</i>)-HPA-12 and (+)-(1<i>S</i>,3<i>R</i>)-HPA-12
作者:Zu-Feng Xiao、Chuan-Zhi Yao、Yan-Biao Kang
DOI:10.1021/ol503261h
日期:2014.12.19
An asymmetric N-demethylative rearrangement of 1,2-isoxazolidines catalyzed by ruthenium is described. Enantioenriched syn-1,3-aminoalcohols as well as cis-1,3-oxazinanes, which are useful building blocks, can be efficiently prepared stereospecifically by this reaction in good yields, via the isoxazolidine intermediates in situ generated from a nitrone bearing a chiral auxiliary and styrenes. This asymmetric reaction was also applied in the asymmetric total syntheses of both (-)-(1R,3S)-HPA-12 and (+)-(1S,3R)-HPA-12.
BF<sub>3</sub>-Mediated <i>cis</i>-Selective Cycloaddition of <i>O</i>-Silyloxime with Alkenes
A C-amide-substituted O-silylated oxime, (E)-(tert-butyldimethylsiloxyimino)acetic acid N,N-dimethylamide (8b), on treatment with 2.2 equiv of BF3 center dot OEt2, in situ generated boracyclic nitrone-type intermediate BF3 center dot 14, which underwent cycloaddition with alkenes to give 3,5-cis-isoxazolidines as the Major products. The mechanism was strongly supported by isolation of the reaction intermediate 14 that was characterized by X-ray diffraction and its further reaction. This cycloaddition was successfully applied to the synthesis of syn-HPA-12 known as an inhibitor of CERT that mediates the transport of ceramide.