Benzoyl dithiocarbazate

Young and Wood (389) did not isolate the intermediate benzoyl dithiocarbazic acids (LXXXII) which readily loose hydrogen sulfide on warming to yield the 5 substituted zl4-l,3,4-oxadiazoIine-2-thiones (LXXXIII). These authors suggested another reaction mechanism involving the intermediate formation of a xanthate type salt (LXXXVI) through nucleophilic attack of the enol form of the carboxylic acid hydrazide (LXXXIb) on carbon disulfide. 

Sato and Ohta (307) who reinvestigated the reaction of dithiocarbazic acids with chloroacetone and w-bromoacetophenone also described the 3.4-dihydro-2H-1,2,4-thiadiazine-2-thione structure to the products. These authors also describe the condensation of N-benzoyl dithiocarbazic acids (CCXV, Rj—CgHjCO with a-halo ketones which yields 4-benzoyl-3,4-dihydro-2H-t, 3,4-thiadiazine-2-thiones (CCXVIII, These products hydrolj ze in acid medium (with formation of benzoic acid) and simultaneously undergo a transformation to 3-amino-zl4-thiazoline-2-thiones. These facts support the remarks made earlier. 

Both N-benzoyl and N-acyl dithiocarbazates react with chloroacetic acid to yield 3-benzoyl- and 3-(acylamino)thiazolidin-4-one-2-thione respectively (CCXX, R RCO) (307, 353). Sometimes the S-carboxy-methyl derivative of 1,3,4-oxadiazoline-/l -2-thione (see Section II.7) (307) is also formed. The formation of a perhydro-l,3,4-thiadiazin-5-one-2-thione, however, was not observed. On warming S-(ethoxy-carbonylmethyl)-N-benzoyl dithiocarbazate (CCXIII) with ammonia though 5-phenyl-6-carbamoyl-3,6-dihydro-2H-l, 3,4-thiadiazine-2-thione (CCXIV) was obtained. 

The products of the reaction between carboxylic acid hydrazides and carbon disulfide cyclize very readily to Zl4-l,3,4-oxadiazoline-2-thiones (LXXXIII) (see Section II.7). The intermediates, the acyl- or benzoyl-dithiocarbazic acids may, however, also be isolated and reacted with alkyl halides to give S-alkyl dithiocarbazates (LXXXVIIIa) which also cyclize easily either to thiadiazoline or oxadiazoline rings according to the reaction circumstances (see Section II.7). 

The reaction of benzoyl dithiocarbazate (142) and 3 gave 5-ethyl sulfanyl-7-OXO-2-phenyl-4,7-dihy dro-indeno[2,3,4-oxodiazocine-6-carbo-nitrile (144) as illustrated in Scheme 45 (1997JCR144). 

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