Dithiocarbamic acid esters acids

Even though the most widely used preparation is still the reaction of alkali isothiocyanates or alkyl and aryl isothiocyanates with a-amino carboxylic acid derivatives, the reaction of dithiocarbamic acid esters (CCX) with a-amino carboxylic acids (CCXI) has certain advantages especially in the synthesis of heterocyclically substituted imidazolidin-4-one-2-thiones (221). 

It appears quite probable that this reaction occurs by the same mechanism as the reaction of nitrous acid with thiosemicarbazides and of sodium azide with isothiocyanates. The primary reaction product is a thiocarbamoyl azide (CCXIII) to which, however, the cyclic structure of a 5-amino-l,2,3,4-thiatriazole (CCXIV) is attributed. In alkaline medium these compounds rearrange to the corresponding 1 -substituted-Zla-tetrazoline-5-thiones (CCXII) 236, 237). A survey of these compounds, prepared from the dithiocarbamic acid esters, is given in Table 33. 

Amide mercaptals Dithiocarbamic acid esters Dithiourethans Iminodisulfides Iminodithiocarbonic acid esters... 

Dithiocarbamic acid esters from bisthiuram disulfides... 

Amide mercaptals Dithiocarbamic acid esters 1,3-Dithiolanium salts,... 

Dialkyl phosphite Dithiocarbamic acid esters and monoalkyl phosphites from dialkyl phosphites... 

S-Phthalimidomethyl compounds Dithiocarbamic acid esters from halides... 

In a weakly alkaline solution, isothiocyanate reacts with the a-amino group of cysteine (Figure 2.64). The reaction of isothiocyanates with cystine leads to the cleavage of disulfide bond (-S-S-) with the formation of cysteine sulfenic acid and a dithiocarbamic acid ester. Dehydration of this ester yields 5-amino-l,3-thiazine-4-one-3-thione derivative and elimination of hydrogen sulfide produces a cyclic 2-thiazoline-4-carboxylic acid derivative (Figure 2.65). Reaction of cystine with thiocyanates (R-S-C=N), formed by spontaneous isomerisation of isothiocyanates, produces disulfide Cys-S-S-R and -thiocyanoalanine, which cyclises to 2-thiazoline derivative (Figure 2.66). 

Pyridine sodium hydrogen carbonate Dithiocarbamic acid esters from isothiocyanates and mercaptans C,HiN/NaHCO, N C S NHC(S)SR... 

---