Reaction of Oxalyl Chloride and Alkyloxalyl Chlorides with Isocyanates and Isothiocyanates

Article abstract of DOI:10.1021/jo00194a001

Alkyl and aryl isothiocyanates react with oxalyl chloride (1) on both double bonds of the heterocumulene to yield 3-alkyl- or 3-aryl-2,2-dichlorothiazolidine-4,5-diones 2.The two chlorines in these novel orthocarbonic acid derivatives are readily exchanged by alkoxy groups to yield 2,2-dialkoxythiazolidine-4,5-diones 3; hydrolysis of 2a (R=CH3) gave 3-methylthiazolidine-2,4,5-trione. 3-Substituted 5,5-dichlorooxazolidine-2,4-diones 8 and 5-chloro-5-alkoxyoxazolidine-2,4-diones 13 are obtained on reacting alkyl, aryl, and benzyl isocyanates with 1 and alkyloxalyl chloride, respectively.Structure assignment to these novel cycloadducts is based on IR, 1H NMR, and 13C NMR spectroscopic as well as X-ray crystallographic analysis.Formation of 8 and 13 is a stepwise process involving labile acyclic intermediates 7 and 12.The cyclizations to 8 and 13 take place only on the C=N bond of the isocyanate group.