Novel ruthenium-catalyzed cleavage of allyl protecting group in lactams
摘要:
A convenient and general method of synthesis of NH-lactams via Grubbs' carbene promoted isomerization of the respective N-allyl lactams followed by RuCl3-catalyzed enamide cleavage has been developed. (C) 2003 Elsevier Ltd. All rights reserved.
Asymmetric radical cyclizations: the synthesis of 6-Alkyl Pyrrolizidin-2-ones
摘要:
This work describes the use of ethyl (5S)-carboethoxy-2-pyrrolidinone (ethyl pyroglutamate) as a chiral starting material for use in radical cyclization reactions. Pyroglutamate is converted to a 5-iodomethyl-N-allylic-2-pyrrolidinone that undergoes radical cyclization under mild conditions. The products are 6-substituted pyrrolizidinone derivatives, produced with high diastereoselectivity.
A Practical Ruthenium-Catalyzed Cleavage of the Allyl Protecting Group in Amides, Lactams, Imides, and Congeners
作者:Benito Alcaide、Pedro Almendros、Jose M. Alonso
DOI:10.1002/chem.200501227
日期:2006.3.20
deprotection of N-allylic amide-like moieties was developed. The first examples accounting for the ruthenium-catalyzed deallylation of amides, lactams, imides, pyrazolidones, hydantoins, and oxazolidinones have been achieved by the sequential use of Grubbs carbene (isomerization step) and RuCl(3) (oxidation step). A variety of substrates, including enantiopure multifunctional beta- and gamma-lactams, can
A General N-Alkylation Procedure for Ethyl Pyroglutamate
作者:Tiberiu Simandan、Michael B. Smith
DOI:10.1080/00397919608002625
日期:1996.5
Abstract Despite several reported procedures for coupling alkylhalides and 5-oxoproline esters (pyroglutamate derivatives), no general method has been described. The reaction of pyroglutamate with sodiumhydride, in anhydrous THF in the presence of the halide, provides this general and practical alkylation method. Alkylation under phase transfer conditions is a useful, but less general, alternative