Enzymes in organic synthesis: remarkable influence of a π system on the enantioselectivity in PPL catalysed monohydrolysis of 2-substituted 1,3-diacetoxypropanes.
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.
RAMOS, TOMBO G. M.;SCHAER, H. -P.;FERNANDEZ, I BUSQUETS X.;GHISALBA, O., BIOCATAL. ORG. MEDIA: PROC. INT. SYMP., WAGENINGEN, 7-10 DEC., 1986, AMST+
作者:RAMOS, TOMBO G. M.、SCHAER, H. -P.、FERNANDEZ, I BUSQUETS X.、GHISALBA, O.
DOI:——
日期:——
TOMBO G. M. RAMOS; SCHAR H. -P.; FERNANDEZ X.; GHISALBA O., TETRAHEDRON LETT., 27,(1986) N 47, 5707-5710
作者:TOMBO G. M. RAMOS、 SCHAR H. -P.、 FERNANDEZ X.、 GHISALBA O.