Sodium sulfide in methanol: a two-in-one reagent for deprotection of silyl and formation of propargyl sulfide
摘要:
A new reagent Na2S/MeOH for silyl deprotection has been developed. The reagent has several advantages which include deprotection of C-TMS, O-TMS, O-TBS, and O-TBDPS, selective removal of C-TMS and O-TMS in the presence of O-TBS and simultaneous desilylation and sulfide formation in one pot. (c) 2015 Elsevier Ltd. All rights reserved.
Platinum and Ruthenium Chloride-Catalyzed Cycloisomerization of 1-Alkyl-2-ethynylbenzenes: Interception of π-Activated Alkynes with a Benzylic C−H Bond
摘要:
Air-stable and commercially available alkynophilic metal salts, such as PtCl2, PtCl4, and [RuCl2(CO)(3)](2), catalyze the cycloisomerization of 1-alkyl-2-ethynylbenzenes to produce Substituted indenes even at all ambient temperature. Electrophilically activated alkynes can be intercepted by simple benzylic C-H bonds at primary, secondary, and tertiary carbon centers. Mechanistic studies, such as labeling studies and kinetic isotope and substituent effects, indicate that the cycloisomerization proceeds through the formation of a vinylidene intermediate and turnover-limiting 1,5-shift of benzylic hydrogen.
Convergent synthesis of pyrrolidines, piperidines, perhydroazepines and tetrahydroisoquinolines via zirconocene η2-imine complexes
作者:Michael C.J. Harris、Richard J. Whitby、Julian Blagg
DOI:10.1016/0040-4039(95)00741-t
日期:1995.6
Zirconoceneη2-iminecomplexes formed by a CH activation route from a variety of amines are trapped by ω-halo-alkenes or -alkynes to afford 2,3-disubstituited pyrrolidines, piperidines and perhydroazepines on work up and cyclisation. In some cases it was necessary to use a protected hydroxyl group rather than the halide and cyclise in a separate step through selective formation of the O-mesylate.