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Lawesson's reagent is a thiation agent used to convert carbonyl compounds into thiocarbonyls. It is also used to thionate enones, esters, lactones, amides, lactams and quinones. Further, it is used to prepare thiols from alcohols. It is associated with silver perchlorate and utilized as and oxophilic Lewis acid catalyst for Diels-Alder reaction of dienes with alfa, beta-unsaturated aldehydes.
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-Tetramethylthiourea, L13392, 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). See Appendix 6.
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).
Kayukova, L. A.; Praliyev, K. D.; Gutyar, V. G.; Baitursynova, G. P. Modification of organic compounds with Lawessons reagent. Russ. J. Org. Chem. 2015, 51 (2), 148-160.
Gholinejad, M. One-Pot Copper-Catalysed Thioetherification of Aryl Halides Using Alcohols and Lawesson's Reagent in Diglyme. Eur. J. Org. Chem. 2015, 2015 (19), 4162-4167.
Hazard Statements: H261-H302-H331-H315-H319-H335
In contact with water releases flammable gas. Harmful if swallowed. Toxic if inhaled. Causes skin irritation. Causes serious eye irritation. May cause respiratory irritation.
Precautionary Statements: P231+P232-P261-P280a-P305+P351+P338-P405-P501a
Handle under inert gas. Protect from moisture. Avoid breathing dust/fume/gas/mist/vapours/spray. Wear protective gloves and eye/face protection. IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing. Store locked up. Dispose of contents/container in accordance with local/regional/national/international regulations.