Powerful thionation agent used for the replacement of the carbonyl oxygen of ketones, amides and esters, by sulfur: Bull. Soc. Chim. Belg., 87, 223, 229, 293, 299, 525 (1978); Tetrahedron, 35, 1339, 2433 (1979). Review: Tetrahedron, 41, 5061 (1985). For conversion of N-methylpyrrolidinone to the thiolactam, see: Org. Synth. Coll., 7, 372 (1990). Uracil and its derivatives are thionated selectively at the 4-position: Synthesis, 152 (1988). Peptides give endo-thiopeptides: Tetrahedron, 37, 3635 (1981). Esters, orthoesters, acetals and epoxides give the thio-analogues: Monatsh. Chem., 115, 769 (1984). Used, in combination with 1,1,3,3-Tetramethyl-thiourea, for formation of bis-thioesters for subsequent radical coupling as a method of ring formation in Nicolaou's syntheses of hemibrevitoxin B and brevitoxin B: J. Am. Chem. Soc., 115, 3558 (1993); 117, 10227 (1995). Reaction with 1,4-diketones gives 2,5-disubstituted thiophenes in high yield: Synthesis, 1061 (1982). Reaction with ɑ-diazo ketones has been used to prepare 1,2,3-thiadiazoles: Heterocycles, 19, 241 (1982). Benzylic and related alcohols are converted to the corresponding thiols: J. Chem. Soc., Chem. Commun., 205 (1989); J. Chem. Soc., Perkin 1, 1113 (1993). Reacts with N-protected amino acids to give mixed anhydrides, useful in peptide coupling: Tetrahedron, 38, 3267 (1982). Has also been found to act as an efficient trapping agent for 1,3-dipoles under very mild conditions. Its powerful dipolarophile character allows it to be used as a "1,3-dipole indicator" even with dipoles of low reactivity, the outcome of the reaction being readily verified by 31P NMR: J. Org. Chem., 60, 3904 (1995).
