Chemoenzymic preparation of asymmetrized tris(hydroxymethyl)methane (THYM*) and of asymmetrized bis(hydroxymethyl)acetaldehyde (BHYMA*) as new highly versatile chiral building blocks
摘要:
A series of asymmetrized tris(hydroxymethyl)methanes 2 and bis(hydroxymethyl)acetaldehydes 3 have been prepared in both enantiomeric forms through a chemoenzymatic methodology. The key step is the highly enantioselective PPL-catalyzed monohydrolysis of 2(E)-alkenyl-1,3-diacetoxypropanes 25-27. A careful study on the effect of unsaturations adjacent to the prochiral center in a series of 2-substituted 1,3-diacetoxypropanes has confirmed the suggested beneficial effect of a pi-system in that position but has also unveiled an unprecedented dramatic effect of double-bond configuration on enantioselectivity. A new empirical model for the interpretation of these and other results, based both on polarity and steric arguments, is proposed. This study provides a general protocol for the efficient synthesis of asymmetrized 1,3-propanediols bearing in position 2 saturated or unsaturated carbon chains.
A Short Access to 3-Hydroxy-4-hydroxymethyltetrahydrofurans: Application to the Total Synthesis of Amphiasterin B4
作者:Hani Salim、Olivier Piva
DOI:10.1021/jo8020659
日期:2009.3.6
The first totalsynthesis of amphiasterin B4, a secondary metabolite previously isolated from Plakortisquasiamphiaster has been achieved. The core structure has been reached according to a highly stereoselective one-pot epoxidation/cyclization of an unsaturated diol. This substrate can be prepared from β,γ-unsaturated diesters readily available from the organocatalyzed protonation of a transient dienol
Enzymes in organic synthesis: remarkable influence of a π system on the enantioselectivity in PPL catalysed monohydrolysis of 2-substituted 1,3-diacetoxypropanes.
作者:Giuseppe Guanti、Luca Banfi、Enrica Narisano
DOI:10.1016/s0957-4166(00)82383-6
日期:1990.1
Preparation of lactones via tricarbonyliron–lactone complexes
作者:Gary D. Annis、Steven V. Ley、Christopher R. Self、Ramamoorthy Sivaramakrishnan
DOI:10.1039/p19810000270
日期:——
A number of tricarbonyliron–lactonecomplexes have been prepared from vinyl oxirans by treatment with pentacarbonyliron. In certain cases two η3-allyl complexes were isolated from a single vinyl oxiran. Oxidation of the complexes by cerium(IV) ammonium nitrate in acetonitrile leads predominantly to β-lactones. The stereochemical integrity of the initial complexes is reflected in the formation of the
Chemoenzymic preparation of asymmetrized tris(hydroxymethyl)methane (THYM*) and of asymmetrized bis(hydroxymethyl)acetaldehyde (BHYMA*) as new highly versatile chiral building blocks
作者:Giuseppe Guanti、Luca Banfi、Enrica Narisano
DOI:10.1021/jo00031a039
日期:1992.2
A series of asymmetrized tris(hydroxymethyl)methanes 2 and bis(hydroxymethyl)acetaldehydes 3 have been prepared in both enantiomeric forms through a chemoenzymatic methodology. The key step is the highly enantioselective PPL-catalyzed monohydrolysis of 2(E)-alkenyl-1,3-diacetoxypropanes 25-27. A careful study on the effect of unsaturations adjacent to the prochiral center in a series of 2-substituted 1,3-diacetoxypropanes has confirmed the suggested beneficial effect of a pi-system in that position but has also unveiled an unprecedented dramatic effect of double-bond configuration on enantioselectivity. A new empirical model for the interpretation of these and other results, based both on polarity and steric arguments, is proposed. This study provides a general protocol for the efficient synthesis of asymmetrized 1,3-propanediols bearing in position 2 saturated or unsaturated carbon chains.