Phosphorus Pentasulfide (P₄S₁₀)

Biographical Sketches

Vivek Polshettiwar was born in Mangli (Village) Maharashtra ­(India) in 1979. He completed his B.Sc. (1999) and M.Sc. (2001) degrees in organic chemistry from Amravati University, Amravati, India. He is currently working as a DRDO-SRF for his Ph.D. under the supervision of Prof. M. P. Kaushik at Defence R & D ­Establishment in Gwalior, India.

Introduction

Organosulfur compounds are valued not only for their rich and varied chemistry, but also for many important ­biological properties. Phosphorous pentasulfide (P₄S₁₀) is very useful and versatile reagent for the synthesis of ­various ­organosulfur compounds. P₄S₁₀ is widely available as a light yellow crystalline solid. It is highly flammable and decomposes in the presence of moisture.

P₄S₁₀ has been extensively used as a thionating agent for the conversion of carbonyls into thiocarbonyls in the preparation of organosulfur compounds. It also activates the free hydroxyl group of an acid or an alcohol to create a good leaving group. It can also be used as a deoxygenating and dehydrating agent.

Abstracts

(A) As a thionating agent: Various carbonyl groups can be converted into the corresponding thiocarbonyl groups by treatment with P4S10. [1] Recently, the combination of P4S10 and HMDO has proved to be a very useful thionating reagent over P4S10 alone. [2]
(B) In the synthesis of Lawesson’s reagent: The most popular thionating reagent can be synthesized by reaction of P4S10 with ­anisole. [3]
(C) As an activating agent: P4S10 activates the free hydroxyl group of carboxylic acids or alcohols to create a good leaving group. When this activation is done in the presence of another nucleophile, a substitution reaction occurs. [4] It is also used for the syn­thesis of dithiocarboxylic esters. [5]
(D) As a deoxygenating agent: P4S10 is one of the mildest selective reagents for the conversion of sulfoxides to sulfides. [6] The reduction takes place selectively without affecting functional groups such as esters, amides or ketones. Interestingly, sulfones are also unreactive under these conditions. [7]
(E) As a dehydrating agent: Use of P4S10 as a dehydrating agent has been reported. The aromatization of a furan Diels-Alder ­adduct using P4S10 in CS2 has been found to be superior than with other reagents like HCl/HOAc or polyphosphoric acid. [8]
(F) As an adduct: The reaction of steroidal molecule 16-dehydropregnenolone acetate (16-DPA) with P4S10 in refluxing benzene afforded a novel adduct 16-DPA-P2S5. This adduct undergoes [4+2] cycloaddition with alkyne dienophiles to afford biologically active steroidal (17,16-c)pyrans. [9]
(G) In the synthesis of thiolactams: Phosphorus pentasulfide reacts under mild conditions with organolithiums to give solutions in tetrahydrofuran. This in situ reagent converts lactams to thiolactams and shows significant selectivity in the type of reactive lactams. [10]
(H) In the synthesis of episulfides: Sterically hindered methyl­enecyclopropanones can be thionated with P4S10 in pyridine to ­afford novel 1,2,3-butatriene episulfides and a thiiranoradialene derivative. [11]

References

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• 1b Polshettiwar V. Kaushik MP. Tetrahedron Lett.  2004,  45:  6255 
• 2 Curphey TJ. J. Org. Chem.  2002,  67:  6461 
• 3 Thomsen I. Clausen K. Scheibye S. Lawesson SO. Org. Synth.  1984,  64:  158 
• 4 Blade-Font A. Aquila S. De Mas T. Torres JM. J. Chem. Res. (S)  1981,  58 
• 5 Sudalai A. Kanagasabapathy S. Benicewicz BC. Org. Lett.  2000,  2:  3213 
• 6 Madesclaire M. Tetrahedron  1988,  44:  6537 
• 7 Micetich RC. Tetrahedron Lett.  1976,  17:  971 
• 8 Cava MP. VanMater JP. J. Org. Chem.  1969,  34:  538 
• 9 Chetia A. Saikia A. Saikia CJ. Boruah RC. Tetrahedron Lett.  2003,  44:  2741 
• 10 Goel OP. Krolls U. Synthesis  1987,  162 
• 11 Ando W. Hayakawa H. Tokitoh N. Tetrahedron Lett.  1987,  28:  1803