Lawesson’s Reagent: Endowed With Wide Utility in Organic Synthesis

Introduction

Lawesson’s Reagent (LR, Figure [1] ), 2,4-bis(4-methoxyphenyl)-1,3-dithia-2,4-diphosphethane-2,4-disulfide is a versatile and effective thionation reagent; [1] it is best known for the conversion of a wide variety of carbonyl into thiocarbonyl compounds, including the synthesis of phosphorus- and sulfur-containing heterocycles, such as thiazolidinediones, [2] thiothalidomides, [3] 2H-benzo[1,4]thiazine, [4] among others. However, this reagent can efficiently be applied to many other reactions, in particular for the deoxygenation of heterocyclic halobenzyl alcohols, [5] to heterocyclization of acetohydrazidepyridines, which yields [1,2,4]triazolo[4,3-a]pyridines, [6] to afford pyrazoles, [7] to [4+2] cycloaddition of α,β-unsaturated ketones, [8] and as a racemization-free coupling reagent in peptide synthesis. [9] LR is stable in solvents like toluene, THF, dichloromethane, and pyridine, [10] it can be used under microwave irradiation and for automated parallel synthesis; it is commercially available and easily prepared by reaction of P₄S₁₀ with anisole under heating. [1]

Figure 1

References

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