Bicyclic delta-lactones with a carbon group at the bicyclic junction C-7a, designed as pseudoiridolactones, were synthesized from alpha-alkyl-alpha-hydroxymethylcyclopentanones via an intramolecular Horner-Wadsworth-Emmons reaction. (c) 2007 Elsevier Ltd. All rights reserved.
Bicyclic delta-lactones with a carbon group at the bicyclic junction C-7a, designed as pseudoiridolactones, were synthesized from alpha-alkyl-alpha-hydroxymethylcyclopentanones via an intramolecular Horner-Wadsworth-Emmons reaction. (c) 2007 Elsevier Ltd. All rights reserved.
Catalytic asymmetric hydroxymethylation of silicon enolates has been achieved. In this reaction, an aqueous solution of formaldehyde can be used to realize an easy and safe procedure, and high enantioselectivities have been obtained. This is the first example of catalytic asymmetric reactions in aqueous media with a chiral scandium complex.
[reaction: see text] Catalytic asymmetric hydroxymethylation of silicon enolates with an aqueousformaldehyde solution has been developed using a chiral bismuth complex. This is the first example of highly enantioselective reactions using a chiral bismuth catalyst in aqueous media. In this paper, we have added Bi(OTf)(3)-1 complex as a "water-compatible Lewis acid". Bi(OTf)3 is unstable in the presence
Lipase-catalyzed kinetic resolution of α-hydroxymethylcycloalkanones with a quaternary carbon center. Chemoenzymatic synthesis of chiral pseudoiridolactones
The resolution of alpha-alkyl-alpha-hydroxymethylcyclopentanones 1 and cyclohexanones 3 has been efficiently achieved by using lipase-catalyzed transesterification reactions with vinyl acetate as the acylating agent. The enantiomeric selectivities were dependent on both the ring size of the cycloalkanone and the bulk of the carbon group located at the stereogenic quaternary center. The resolved alpha-alkyl-alpha-hydroxymethylcyclopentanones 1 were used as enantiopure (or enantioenriched) precursors for the synthesis of the optically active pseudoiridolactones 6-7. (C) 2010 Elsevier Ltd. All rights reserved.
Bicyclic delta-lactones with a carbon group at the bicyclic junction C-7a, designed as pseudoiridolactones, were synthesized from alpha-alkyl-alpha-hydroxymethylcyclopentanones via an intramolecular Horner-Wadsworth-Emmons reaction. (c) 2007 Elsevier Ltd. All rights reserved.