The protocol of lithiation by means of lithium and a catalytic (5% molar) amount of DTBB (4,4’-di-tert-butylbiphenyl), applied to ω-chloro ortho ester 6 under Barbier-type conditions gives, after final acid-catalyzed methanolysis, the corresponding functionalized esters 8 or 9 (for chlorotrimethylsilane as electrophile) or, after ortho ester deprotection and acid catalyzed treatment, the δ-lactones 11. The procedure is also practical for bicyclic ortho esters 14: the β-chloro OBO ester derivate generates the γ- lactones 15 and the γ-chloro OBO ester gives corresponding esters 8.
The key role of water in the heterogeneous permanganate oxidation of ω-hydroxy alkenes
作者:Sundarababu Baskaran、Imadul Islam、Padma S. Vankar、Srinivasan Chandrasekaran
DOI:10.1039/c39900001670
日期:——
Potassium permanganate–copper sulphate in dichloromethane in the presence of a catalytic amount of water effects a smooth oxidative cyclization of ω-hydroxyalkenes to ω-lactones in good yields with the net loss of one or more carbon atoms in the process.
A Novel Synthesis of γ,δ-Unsaturated Aldehydes from α-Formyl-γ-lactones
作者:Roger L. Snowden、Robert Brauchli、Simon Linder
DOI:10.1002/hlca.201000447
日期:2011.7
A preparatively useful one‐step transformation of γ,γ‐disubstituted α‐formyl‐γ‐lactones into trisubstituted γ,δ‐unsaturated aldehydes is described, by means of catalytic amounts of either AcOH or AcOEt in the vapor phase over a glass support. A mechanistic rationale is proposed.
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