Chemo‐ and Regioselective Preparation and Reaction of a Kinetic Zinc Enolate Formed from a Thiol Ester and Bis(iodozincio)methane

Abstract

Reactive functionalized enolates that are otherwise difficult to obtain can be prepared in a simple procedure by the treatment of a thiol ester with bis(iodozincio)methane in the presence of a palladium catalyst (see scheme). The terminal zinc enolates thus formed are kinetically controlled and react with a variety of electrophiles, such as aldehydes, ketones, and acyl cyanides. FG=functional group.

2-(2,2,2-Trifluoroethylidene)-1,3-dithiane Monoxide as a Trifluoromethylketene Equivalent

“…We anticipated that 1a would react with nucleophile at C1 under extended Pummerer reaction conditions , to yield ketene dithioacetal 2 , which might be a very attractive intermediate for further transformation (Scheme ). Hydrolysis of ketene dithioacetal 2 could provide thiol ester 3 , which should react with nucleophile at C2 to give α-trifluoromethyl ketone 4 . Alternatively, reduction of 2 could afford dithiane 5 , which can participate in the conventional dithiane chemistry .…”

“…Treatment of ketene dithioacetal 9a with aqueous hydrochloric acid in acetonitrile followed by methylation yielded thiol ester 10 , which is a good electrophile in the reactions with various nucleophiles (Scheme ) . For instance, palladium-catalyzed cross-coupling reactions of thiol ester 10 with organozinc reagents afforded α-trifluoromethyl ketones 11a and 11b in good yields.…”

Diastereoselective Intermolecular Cobalt-Catalyzed Reductive Aldol Reactions of α,β-Unsaturated Amides with Ketones

“…Zinc enolates are an important class of reagents for organic synthesis, readily reacting with a range of electrophiles, − and exhibiting lower basicity and greater functional group compatibility compared to their alkali metal counterparts. There are several common methods to access zinc enolates using stoichiometric zinc sources. , …”

Chemo-, regio- and stereoselective preparation of silyl enol ethers from thiol esters and bis(iodozincio)alkane

“…4 We had also shown that the palladium-catalyzed cross-coupling reactions of bis(iodozincio)methane with several thiol esters affords the zinc enolate selectively which corresponds to the terminal enolate of methyl ketone. 5,6 In this communication, we report on the chemo-, regio-and stereoselective preparation of silyl enol ethers based on the cross-coupling reaction of gem-dizincioalkane and various thiol esters (Scheme 1).…”