Dithiocarboxylic esters

Addition of lithium dialkylcopper reagents to dithiocarboxylic esters... 

Thione-S-oxides react regiospecifically with allyl and benzylsilanes in the presence of a stoichiometric amount of tetra-n-butylammonium fluoride to produce allyl and benzyl sulphoxides [8], cf. the analogous fluoride initiated reaction of thio-ketones and dithiocarboxylic esters with silanes [9, 10]. The yields of sulphoxides... 

Carbon disulphide should not be used as the solvent for alkylation of fS-diketones, as the carbanion reacts preferentially with the solvent to generate the dithiocarboxyl-ate derivative, which undergoes mono- and dialkylation (Scheme 6.9) [95]. Ketene thioacetals have also been isolated from acetophenones (60-80%) and cyclopenta-diene (80%) using an ultrasound technique in carbon disulphide [96] and, in a similar manner, pyrazol-5-ones form pyrazole-4-dithiocarboxylic esters [97]. 

BC13 convert 0=0 groups of ketones, lactones, and lactams to G=S groups119 and H2S-Me3SiCl-i-Pr2NLi converts carboxylic esters to thiono esters.120 Carboxylic acids RCOOH can be converted directly to dithiocarboxylic esters RCSSR, 120a in moderate yield, with P4S, and a primary alcohol R OH.121 Thioketones can also be prepared by treatment of ketones with P4SI0,122 and from oximes or various types of hydrazone (overall conversion C=N------> C=S).123... 

Another method involves anionic cycloaddition of triethylammonium salts of dithioacids or dithiocarbonates to dimethyl acetylenedicarboxylate to produce the 1,3-dithioles (302) (81ZOR1788, 80ZOR2616). Also dithiocarboxylic esters react with dimethyl acetylenedicarboxylate giving substituted 1,3-dithioles (303) (80ZOR2047,79ZOR1106). 

Boron-substituted heteroaromatic compounds 89AHC(46)143. Dithiocarboxyl esters 88SR(8)155. 

Thioesters of the type RSC(=S)R (a dithiocarboxylic ester) and RSC(C=0)R (a thiocarboxylic ester) can be generated by reaction of carboxylic acids with thiols. 

Transesterification of dithiocarboxylic esters with alcohols or alcoholates occurs in the presence of bases. In particular, the highly reactive sodium salts of methoxycarbonyl carbodithioates are used, which can be applied conveniently in aqueous solution or, if hydrolysis has to be avoided, in dry... 

Although, presumably, dithiocarboxylic esters are prepared by alkylation of the strongly nucleophilic dithiocarboxylate salts in most cases (Action 2.5.1), Aioacylation procedures provide a valuable altema-tive.6 15 26.27,29,140.141 jj, particular, the sulfhydrolysis of imidothioates (Section 2.5.4.3) has retained its importance due to the convenient availability of the starting material, a nitrile or thioamide. 

Stable, as well as transient, thioketenes give dithiocarboxylic esters on reaction with thiols (equation 61). ... 

The interchange reaction between a thioxoester and a thiol does not, in general, represent a meaningful synthetic procedure since dithioesters are more readily available than thioxoesters in most cases. However, 0,S-diethyl tiithiomalonate (61b) and diethyl tetrathiomalonate (61c) were prepared from 0,0-di-ethyl dithiomalonate (61a). On the other hand, the transformation of one dithiocarboxylic ester into another can be a useful and practicable reaction. For instance, ethyl arenecarbodithioates are intercon-verted to 2-dialkylaminoethyl arenecarbodithioates, according to equation (62). 

Imidothioates in the neutral or ionic form are the most generally applied educts for the preparation of dithiocarboxylic esters. They are themselves prepared from nitriles, thioamides or isothiocyanates, and react with hydrogen sulfide under appropriate conditions to yield the dithioesters (Scheme 7) 6,14,26,27,29,141 Interesting examples (62)-<73) were described in the recent literature. 

The condensation products of dithiocarboxylic esters with aldehydes are readily converted to ketene dithioacetals. " ... 

Both cis and rrafw-3-phenoxycinnamic acids cyclize with phosphorus pentoxide to pyran>4-ones but the corresponding phenylthiocinnamic acid isomers behave differently the traits isomer gives a thiopyranone whereas the cis compound produces an indenone. Diels-Alder reactions with heterodienes have been reviewed [24SS, 3067a, 3880]. Indole-3-dithiocarboxylate esters act as dienes in the Diels-Alder reaction with DMAD (cf. Chapter 65, Section II.7). 

Intramolecular cathodic cyclization of dithiocarboxylic esters was studied the cathodic reduction of (175) was found to give the benzothiepine (176) as shown (Scheme 30) <92CBI27>. 

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