Aggregative activation and carbanion chemistry : complex base deprotonation and directed functionalisation of dithioacetals
摘要:
Bis(phenylthio)methane and [1,3]-dithiane were efficiently deprotonated by the NaNH2-Et(OCH2CH2)(2)-ONa complex base. A marked behaviour difference was observed between the sodium carbanion of [1,3]-dithiane and the corresponding lithio-derivative; A ''radicaioid'' mechanism is proposed to explain the results observed. Copyright (C) 1996 Elsevier Science Ltd
Two novel, non-thiolic, odorless dithiol equivalents, α,α-diacetyl cyclic ketene dithioacetals 2a and 2b, had been developed. A range of carbonyl compounds 3 were converted into corresponding dithioacetals, dithianes 4 and dithiolanes 5, in high yields (up to 99%) in the presence of 2a or 2b. Moreover, 2a and 2b show high chemoselectivity between aldehyde and ketone in thioacetalization.
equivalent, 1 was investigated in the thioacetalization reaction. Various types of aldehydes and ketones 3 were converted to the corresponding dithianes 4 in the presence of 1 in high yields (79-97%). Moreover, 1 exhibited obvious chemoselectivity betweenaldehyde and ketone in this thioacetalization reaction. A mechanism for this thioacetalization reaction is proposed.
Tandem Carbon−Carbon Bond Constructions via Catalyzed Cyanation/Brook Rearrangement/C-Acylation Reactions of Acylsilanes
作者:Xin Linghu、David A. Nicewicz、Jeffrey S. Johnson
DOI:10.1021/ol0263649
日期:2002.8.1
see text] A tandem nucleophile-catalyzed cyanation/Brookrearrangement/C-acylation has been developed. Phase transfer cocatalysts facilitate cyanide-catalyzed reactions between acylsilanes and cyanoformates to afford protected tertiary carbinol products. A catalytic cycle is proposed involving cyanation of an acylsilane, [1,2]-Brook rearrangement, and C-acylation of the derived carbanion by a cyanoformate
An Expeditious Synthesis of Dithioacetals Using Zeolites
作者:Pradeep Kumar、Ravinder S. Reddy、Anand P. Singh、Bipin Pandey
DOI:10.1055/s-1993-25796
日期:——
A simple and efficient catalytic method for dithioacetalization of various carbonyl compounds (saturated and α,β-unsaturated aliphatic, aromatic, heteroaromatic and hindered) with ethanethiol and 1,3-propanedithiol using H-Y and H-mordenite (H-M) zeolites is described. The reaction affords moderate to excellent yields of the corresponding products.
An efficient and chemoselective method for preparation of acetals and dithioacetals of aldehydes and their deprotection under catalysis of InF3 is described.