Enantioselective synthesis of δ-/γ-alkoxy-β-hydroxy-α-alkyl-substituted Weinreb amides via DKR–ATH: application to the synthesis of advanced intermediate of (−)-brevisamide
A method of preparing stereodefined δ-/γ-alkoxy-β-hydroxy-α-alkyl-substituted Weinreb amides containing two successive hydroxyl-alkyl stereocenters has been developed. Further, this strategy coupled with organo-catalyzed asymmetric epoxidation culminates in the synthesis of a critical intermediate of (â)-brevisamide and its diastereomers.
Efficient Synthesis of γ-Alkylidenetetronic Esters by Sequential Lewis Acid Catalyzed [3 + 2] Cyclizations and Palladium-Catalyzed Cross-Coupling Reactions
A newapproach for the synthesis of gamma-alkylidenetetronic acids and esters is reported which involves Me3SiOTf-catalyzed, regio- and stereoselective cyclization of 4-alkoxy-1,3-bis(trimethylsilyloxy)-1,3-butadienes with oxalylchloride. The alpha-hydroxy group of the butenolides is efficiently functionalized by palladium-catalyzed cross-coupling reactions via the corresponding enol triflates.
Synthesis of Indolequinones from Bromoquinones and Enamines Mediated by Cu(OAc)<sub>2</sub>·H<sub>2</sub>O
作者:Martyn Inman、Christopher J. Moody
DOI:10.1021/jo101071c
日期:2010.9.3
A Cu(II)-mediated synthesis of indolequinones from the corresponding bromoquinones and enamines is reported. The key oxidative cyclization proceeds in good yield for a broad range of substrates and can be performed on a multigram scale, allowing access to biologically interesting structures.
[2,3]-Wittig rearrangement of γ-allyloxy-β-ketoesters. A new access to tetronic acids
作者:Isabelle Pévet、Christophe Meyer、Janine Cossy
DOI:10.1016/s0040-4039(01)00982-0
日期:2001.7
Dilithiated gamma -allyloxy-beta -ketoesters undergo a [2,3]-Wittig rearrangement leading to protected gamma -hydroxy-beta -ketoesters, which can be converted to tetronic acids. (C) 2001 Elsevier Science Ltd. All rights reserved.