Dithiomalonates, 0,0-diethyl

A detailed study of the electronic spectra of the d8 complexes [M(dto)2]2 (M = Ni, Pd, Pt) and [Au(dto)2] has been reported. The spectra are virtually identical in a variety of solvents, indicating that axial perturbations due to the solvent are minimal. Dithiooxalate has a high position among square-planar NiS4 chromophores in the spectrochemical series for dithio ligands the series is maleonitriledithiolate < (CF3)2C2S2 < diethyl dithiophosphate < ethyl xanthate < diethyl dithio-carbamate < 2,3-dimercaptopropanol anion < dithiomalonate dithiooxalate.145... 

In the presence of a tertiary amine, particularly DABCO, S,S -diethyl dithiomalon-ate undergoes 1,4-addition to 2,/ -enones and a,/ -unsaturated esters that are not disubstituted in the /(-position. The products are reduced by acid-washed Raney nickel to 1,5-ketols and 5-hydroxy esters.2... 

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). 

A new variant of the malonate synthesis (Scheme 6) using S,S -diethyl dithiomalonate provides good yields of primary alcohols in a two-carbon homologation/ The central feature is a one-step dealkylthiocarbonylation-reduction with Raney nickel of the alkylated malonates (6) and (7). 

Various routes to OO-diethyl dithiomalonate (202a) have been described, together with methods for its conversion into the analogous dithioester (202b) and bis-dithioester (202c). A simple procedure has been developed for the synthesis of unsymmetrical bis-acyl disulphides (203) from two thiobenzoic acids. ... 

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