Asymmetric synthesis of tetrahydrolipstatin and valilactone
摘要:
The highly diastereoselective aldol reaction between acyl complexes of the iron chiral auxiliary [(eta(5)-C5H5)Fe(CO)(PPh3)] and beta-hydroxy aldehydes (obtained via a Noyori asymmetric hydrogenation), followed by a tandem oxidative decomplexation-cyclisation process gives access to beta-substituted and alpha,beta-disubstituted beta-lactones in high ee. This methodology has been employed in the asymmetric syntheses of tetra hydrolipstatin and valilactone. (C) 2008 Elsevier Ltd. All rights reserved.
A facile method for synthesis of three carbon-homologated carboxylic acid by regioselective ring-opening of β-propiolactones with organocopper reagents
β-carbon-oxygen fission to give 3-substituted propionic acids. Among these three kinds of organocopper reagents, diorganocuprate, especially halomagnesium cuprate gave the highest yields of the acids, which was remarkably observed in the ring-opening of sterically hindered β-propiolactones such as β-methyl- and α,β -dimethyl-β-propiolactones and also in the reactions using the organocopper reagents with vinyl and
Practical β-Lactone Synthesis: Epoxide Carbonylation at 1 atm
作者:John W. Kramer、Emil B. Lobkovsky、Geoffrey W. Coates
DOI:10.1021/ol061292x
日期:2006.8.1
text] A readily prepared bimetallic catalyst is capable of effecting epoxide carbonylation to produce beta-lactones at substantially lower CO pressures than previously reported catalyst systems. A functionally diverse array of beta-lactones is produced in excellent yields at CO pressures as low as 1 atm. This procedure allows for epoxide carbonylation on a multigram scale without the requirement of specialized
Chromium(III) Octaethylporphyrinato Tetracarbonylcobaltate: A Highly Active, Selective, and Versatile Catalyst for Epoxide Carbonylation
作者:Joseph A. R. Schmidt、Emil B. Lobkovsky、Geoffrey W. Coates
DOI:10.1021/ja051874u
日期:2005.8.1
of a tetracarbonylcobaltate anion and an octahedral chromium porphyrin complex axially ligated by two THF ligands. Regarding the carbonylation of epoxides to beta-lactones, catalyst 1 exhibits excellent turnover numbers (up to 10,000) and turnover frequencies (up to 1670 h(-1)), with regioselective carbonyl insertion occurring between the oxygen and the sterically less hindered carbon of the epoxide
作者:Michael E. Green、Jason C. Rech、Paul E. Floreancig
DOI:10.1002/anie.200802548
日期:2008.9.8
The total synthesis of the potent cytotoxin theopederin D has been achieved through the use of an oxidative carbon–carbon bond cleavage reaction to form an acyliminium ion in the presence of acid labile acetal groups Other key transformations include an acid mediated functionalization of a tetrahydrofuranyl alcohol in the presence of a tetrahydropyranyl alcohol, a syn-selective glycal epoxide opening, and a catalytic asymmetric aldehyde-acid chloride condensation.
[Lewis Acid]+[Co(CO)4] Complexes: A Versatile Class of Catalysts for Carbonylative Ring Expansion of Epoxides and Aziridines
作者:Viswanath Mahadevan、Yutan D. Y. L. Getzler、Geoffrey W. Coates