Abstract
Selenocarboxylic acids [RC(=O)SeH] were found to readily react with aryl, acyl, and arenesulfonyl isocyanates to give the corresponding acyl carbamoyl selenides 3 [RC(=O)SeC(=O)NHR′, R′ = aryl, C~6~H~5~CO, and 4‐MeC~6~H~4~SO~2~] in good yields. Their tautomers [RC(=O)SeC(=NR′)OH] were also detected by ^1^H, ^13^C, and ^77^Se NMR spectroscopies. The structure of 3 [R = 2,6‐(MeO)~2~C~6~H~3~, R′ = 4‐MeC~6~H~4~] was characterized by X‐ray crystallography, which showed that this molecule is stabilized by an intramolecular hydrogen bond between the carbonyl oxygen and the NH hydrogen to form a planar six‐membered ring and by nonbonded interaction of the ortho methoxy oxygen with the carbonyl oxygen or the selenium atoms. 4‐Methoxybenzoyl and 4‐methoxythiobenzoyl N‐(4‐methylphenyl)carbamoyl sulfides (4 and 5) were shown by X‐ray crystallography to similarly have a planar intramolecular six‐membered ring formed by a hydrogen bond between the carbonyl oxygen or thiocarbonyl sulfur and NH hydrogen atoms. The tautomers [RC(=E)SC(=NR′)OH; E = O or S] of 4 and 5 also were detected spectroscopically. The reactions of 3h (R = 4‐MeOC~6~H~4~, R′ = Ph) with sodium methoxide and p‐toluidine gave sodium selenocarboxylate and the corresponding amides and urea as main products, respectively. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:250–258, 2001