Dithiadiphosphetans

4-Dithiadiphosphetans.—2,4-Disubstituted 1,3,2,4-dithiadiphosphetan 2,4-disulphides (155) are the anhydrides of dithiophosphonic acids. They have been prepared by the reaction of (156) with The di-t-butyl derivative (155  

R = Bu ) has been prepared from tetra-t-butylcyclotetraphosphine by heating with excess sulphur, and (155 R = Ph) from bis(trifluoromethylthio)phenyl-phosphine and sulphur. These anhydrides, particularly (155 R=p-anisyl), have been exploited for the preparation of thiocarbonyl groups from the corresponding carbonyls (replacing the more obnoxious P2S5) e.g., thioketones,  

Baudler, C. Gruner, G. F. Furstenberg, B. Kloth, F. Saykowski, and U. Oezer, Z. Anorg. Allg. Chem., 1978,446, 169. 

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THIATION WITH 2.4-BIS(4-NETHOXYPHENYL)-1.3.2.4-DITHIADIPHOSPHETANE 2.4-01SULFIDE N-ICTHYLTHlOPYRROLIDONE... 

Bis-(methylthio)-l,3,2X, 4X -dithiadiphosphetane-2,4-dithione (Davy s reagent) [82737-61-9] M 284.4, m 160°. Recrystd from C6H6 in yellow plates or from hot trichlorobenzene. The low m observed in the literature (112° with gradual softening at 68-102°) has been attributed to the presence of elemental sulfur in the crystals. [Tetrahedron 40 2663 1984 J Org Chem 22 789 1957.]... 

The preparation of the 1,3,2,4-dithiadiphosphetane 2,4-disulphi.des (110 R=Me, Et, Pr, or Ph) has been described. Some new sulphur-containing compounds including the oximino esters (111 isolable as their methyl esters) and the dihydro-... 

Fewer routes are known for the preparation of dithiophosphonic acids. Nevertheless sodium dithiophosphophonates have been prepared in high yields from reaction of dithiadiphosphetane disulfides with a sodium alkoxide or aryloxide in the corresponding alcohol solution (Equation 25).40,41... 

Diathiadiphosphetane disulfides are probably the most studied and the most thermally and hydrolytically stable of all the phosphorus-chalcogen heterocycles. They contain a central four membered P2S2 ring and can be prepared from heating phosphorus pentasulfide with aromatic compounds. The most well-known of these is Lawesson s reagent (43), which is made from anisole and phosphorus pentasulfide,92 and is used extensively in organic synthesis procedures (see Section 5.4.1). Other dithiadiphosphetane disulfides of note are 44 and 45, formed from the reaction of phosphorus pentasulfide with ferrocene or 1 -bromonaphthalene respectively.93... 

In contrast to 43-45 the non-aromatic dithiadiphosphetane disulfides are much more difficult to prepare, requiring the use of high temperatures and hydrogen sulfide (Equation 70).94... 

A review of the chemistry of compounds containing a phosphorus-chalcogen bond includes mention of dithiadiphosphetanes <00YGK208>. The first stable pentacoordinate 1,2-thiaphosphetene 47 has been described <99PS119> and l,2-thiaphosphole-2-sulfides 48 have... 

Bis-(4-methoxyphenyl)-[l,3,2,4]dithiadiphosphetane 2,4-disulfide, transforms the carbonyl groups of ketones, amides and esters into the corresponding thiocarbonyl compounds. Cf. Knorr thiophene synthesis. 

Thiopyrimidines can be prepared by thiolysis of halopyrimidines or by thiation of pyrimidinones with phosphorus pentasulfide or Lawesson s reagent (2,4-bis-/i-methoxyphenyl-l,3,2,4-dithiadiphosphetane-2,4-disulfide) <2003JOC9971>. The dithiation of uracil and thiamine has also been performed with the assistance of microwave irradiation using phosphorus pentasulfide absorbed on silica gel <2001SC2231>. 

The addition of H2S to an aldehyde or ketone can result in a variety of products. The most usual product is the trithiane 9.m a-Hydroxy thiols (6) can be prepared from polychloro and polyfluoro aldehydes and ketones.110 Apparently 6 are stable only when prepared from these compounds, and not even for all of them. Thioketones2 (7) can be prepared from certain ketones, such as diaryl ketones, by treatment with H2S and an acid catalyst, usually HCI. They are often unstable and tend to trimerize (to 9) or to react with air. Thioaldehydes111 are even less stable and simple ones112 apparently have never been isolated, though f-BuCHS has been prepared in solution, where it exists for several hours at 20°C.111 A high-yield synthesis of thioketones involves treatment of acyclic114 ketones with 2,4-bis(4-methoxyphenyl)- ,3,2,4-dithiadiphosphetane-2,4-disulfide 10 (known as Lawesson s... 

Bis-(Jp-tolylthio)-l,3,2A,5,4A5-dithiadiphosphetane-2,4-dithione (Heimgartner s reagent) [114234-09-2] M 436.6, m 175-176°. Recrystallise from toluene(light yellow solid), wash with Et20 and dry in a vacuum. [HCA 70 1001 1987]. 

PEPTIDES 2,4-B i s(4-methoxyphenyI)-l,3,2,4-dithiadiphosphetane-2.4-disulfidc 5-Bromo-7-nitroindoline. Diphenyl-2-keto-3 i>xazolinylpho ph[Pg.314]

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