Solvent- and supporting electrolyte-free electrolysis in a two-compartment cell proved to be effective for the direct electroactivation of CH acid-containing compounds vs. catalytic addition processes. Michael adducts (including quaternary carbon centres) and 2-nitroalkanols were obtained in very good yields and selectivity on application of a catalytic amount of electricity under galvanostatic conditions
Nickel(II)-catalyzed Michael additions. Formation of quaternary centers and diastereoselective addition of enantiopure N -acetoacetyl-4-benzyloxazolidin-2-one
Ni(acac)2 and Ni(salicylaldehydate)2 are effective catalysts for conjugate additions of 2-methyl-1,3-dicarbonyl compounds to Michael acceptors. Significant diastereomeric excesses are obtained in the Michael additions of enantiopure N-acetoacetyl-4-benzyloxazolidinones. Reaction of the latter compound with aryl isocyanates affords unsymmetrical diamides of malonic acid.
Studies culminating in the total synthesis and determination of the absolute configuration of (−)-saudin
作者:Robert K. Boeckman、Maria Rico del Rosario Ferreira、Lorna H. Mitchell、Pengcheng Shao、Michael J. Neeb、Yue Fang
DOI:10.1016/j.tet.2011.09.067
日期:2011.12
A full account of studies that culminated in the total synthesis of both antipodes and the assignment of its absolute configuration of Saudin, a hypoglycemic natural product. Two approaches are described, the first proceeding though bicyclic lactone intermediates and related second monocyclic esters. The former was obtained via asymmetric Diels–Alder cycloaddition and the latter by an asymmetric annulation