Studies on the Mechanism, Selectivity, and Synthetic Utility of Lactone Reduction Using SmI<sub>2</sub> and H<sub>2</sub>O
作者:Dixit Parmar、Lorna A. Duffy、Dhandapani V. Sadasivam、Hiroshi Matsubara、Paul A. Bradley、Robert A. Flowers、David J. Procter
DOI:10.1021/ja906396u
日期:2009.10.28
esters and lactones have long been thought to lie outside the reducing range of SmI(2), activation of the lanthanide reagent by H(2)O allows some of these substrates to be manipulated in an unprecedented fashion. For example, the SmI(2)-H(2)O reducing system shows complete selectivity for the reduction of 6-membered lactones over other classes of lactones and esters. The kinetics of reduction has been
Radical Cyclization Cascades of Unsaturated Meldrum’s Acid Derivatives
作者:Brice Sautier、Sarah E. Lyons、Michael R. Webb、David J. Procter
DOI:10.1021/ol2029367
日期:2012.1.6
Unsaturated, differentially substituted Meldrum's acid derivatives undergo cascade cyclizations upon ester reduction with Sml(2)-H2O. The cascade cyclizations proceed in good yield and with high diastereocontrol and convert simple, achiral starting materials to complex molecular architectures, bearing up to four stereocenters, In a single operation. The cascades are triggered by the generation and trapping of unusual radical-anions formed by electron transfer to the ester carbonyl.