Oxalyl ring closures with

Cyclization of ethyl 3-cyano-3-methyl butyrate 201 with hydrazine hydrate gave the hydrazonopyridazine 202, which underwent ring closure with oxalyl chloride to give (85MIP1) pyridazinotriazine derivative 203. 

Without additional reagents Ring closures with oxalyl chloride... 

A soln. of 3-(3,4-dichlorophenyl)-l-isopropyl-l-(2-propynyl)urea and oxalyl chloride in benzene refluxed 8 hrs. 3-(3,4-dichlorophenyl)-l-(2-propynyl)-parabanic acid. Y 81.5%.—This is a convenient synthesis of 1,3-subst. parabanic acids from readily available 1,1,3-trisubst. ureas. F. e., also from thioureas, s. P. J. Stoffel, J. Org. Ghem. 29, 2794 (1964) f. ring closures with oxalyl chloride s. J. Org. Ghem. 29, 2796 parabanic acids from ureas and 2-iminothiazolidine-4 -diones from thioureas s. H. Ulrich and A. A. R. Sayigh, J. Org. Ghem. 30, 2781 (1965). 

Ring closure with oxalyl diloride Parabanic acids from ureas... 

In the first total synthesis of the alkaloid erysotrine, the pyrroloisoquino-line ring 132 was prepared from (5 )-3,4-dimethoxyphenylalanine methyl ester and methyl chloroformylacetate, followed by ring closure and condensation with oxalyl chloride [92H(33)497]. 

Several reactions are occurring in this step that have been elucidated by others (1). First, an a-ketoester is the initial condensation product of an N-acyl-aminoacid and an alkyl oxalyl chloride via a Dakin-West reaction. Second, at reflux temperatures isomeric enol esters are formed that directly condense with hydrazine to form a triazinone intermediate followed by the second ring closure. Other purines have been prepared in an analogous reaction pathway (2). 

Chloroformamidines are not produced in the reaction of thioureas with oxalyl chloride, because ring closure occurs and 2-imino-l,3-thiazolidin-4,5-diones (XV) are obtained in high yield ( ). The heterocyclic derivatives XV isomerize readily to form thioparabanic acids XVI... 

This chemiluminescent reaction was suggested as occuring via ring opening of the cyclic carbonate group with subsequent ring closure to the peroxide (2). An alternative is formation of the diperoxy acid (3). Although a relationship to oxalyl chloride and peroxyoxalate chemiluminescence seems reasonable, details of the excitation step are not known. 

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