Acyl carbamoyl selenides and related sulfur isologues: Synthesis and X-raystructural analyses

Selenocarboxylic acids [RC(=O)SeH] were found to readily react with aryl, a cyl, and arenesulfonyl isocyanates to give the corresponding acyl carbamoyl selenides 3 [RC(= O)SeC(= O)NHR', R' = aryl, C6H5CO, and 4-MeC6H4SO2] in g ood yields. Their tautomers [RC(= O)SeC(=NR')OH] were also de tected by H-1 , C-13 and (77)Sg NMR spectroscopies. The structure of 3 [R = 2,6-(MeO)(2)C 6H3 R' = 4-MeC6H4] was characterized by X-ray crystallography, which showed that this molecule is stabilized by an intramolecular hydrogen bond betwee n she carbonyl oxygen and the NH hydrogen to form a planar six-membered rin g and by nonbonded interaction of the ortho methoxy oxygen with the carbony l oxygen or the selenium atoms. 4-Methoxybenzoyl and 4-methoxythiobenzoyl N -(4-methylphenyl)carbamoyl sulfides (4 and 5) were shown by X-ray crystallo graphy to similarly have a planar intramolecular six-membered ring formed b y a hydrogen bond between the carbonyl oxygen or thiocarbonyl sulfur and NH hydrogen atoms. The tautomers [RC(= E)SC( = NR')OH; E = O or Si of 4 and 5 also were detected spectroscopically. The reactions of 3h (R = 4-MeOC6H4, R' = Ph) with sodium methoxide and p-toluidine gave sodium selenocarboxylat e and the corresponding amides and urea as main products, respectively. (C) 2001 John Wiley & Sons, Inc.