Nucleophiles, reaction with 1,2-dithiolium salts

Nitrogen nucleophiles react at C(3) (C(5)) to form 1,2-dithioles. The further products of the reactions depend on the substitution pattern of the dithiolium ring, the actual nucleophile, and occasionally the reaction medium. Dithiolium salts with nonreplaceable substituents react with ammonia to form isothiazoles (38) and with primary or secondary amines to form aminothiones (39) (Scheme 2) <65JCS32, 80AHC(27)151>. 

Reactions with Nucleophilic Reagents In close parallel with the oxidation of tropilidene derivatives by tropylium salts,81 for example, 1,2-dithiolium salts containing a single substituent in position 4 or 5, e.g. 70, can capture a hydride anion from the doubly substituted, highly strained leuco bases (71), thus oxidizing the latter to the more highly substituted and thermodynamically more stable salts (73).82... 

The yields of these reactions again depend largely on the substituents in the dithiolium salt good yields are obtained from 5-monosubstitu-ted salts, whereas the yields obtained from 4,5-disubstituted salts are only moderate. The methides such as l-methyl-2-methylene-benzothiazoline (133) are also sufficiently nucleophilic to react with trithionium salts, the product obtained from 108 and 133 being the monomethine 134. 

Other reactions of 3-chloro-1,2-dithiolium salts with carbon nucleophiles facilitated by electron-releasing nitrogen groups include 5-aryl-3-chloro-1,2-... 

Reaction of 4-aryl-1,3-dithiolium salts with 2 moles of potassium O-ethyl dithiocarbonate in acetone affords 160 and not the expected adduct. This result has been explained by the solvation effect of the nucleophile which depends on the dielectric constants of acetone and acetonitrile. Treatment of 160 with perchloric acid yields the starting cation with evolution of hydrogen sulfide (Eq. 40). 

After the discovery of the interesting electrical properties of tetrathia-fulvalene (TTF)-tetracyanoquinodimethane (TCNQ) complexes, many TTF derivatives have been prepared by reaction of 1,3-dithiolium salts with tertiary amines. This reaction has been interpreted as proceding by deprotonation of a 1,3-dithiolium cation to the corresponding carbene which in turn reacts as a nucleophile on the C-2 of another 1,3-dithiolium cation. This topic having been recently reviewed, we refer in Table 309,310 Qjjjy jQ papers subsequent to this review. ... 

Dithiolium salts react with the phosphoranes 178. When excess triethylamine is added in the reaction mixture, a TTF derivative is obtained. In a first step, 178 undergoes nucleophilic addition to the 1,3-dithiolium cation. Then triethylamine brings about elimination of triphenylphosphine and formation of TTF (Scheme 31). This synthesis allows the preparation of... 

The reactions of 1,2-dithiole-3-thiones (2b) with various types of halogen reagents forming 3-halo-l,2-dithiolium cations (29b) <76PS(1)185> can be treated as a nucleophilic attack of a halide ion, or a halogen source on a type of initially formed 3-halothio-1,2-dithiolium salt (69b). 

Dithioles with hydroxy and thiol substituents are protonated forms of l,2-dithiole-3-ones (2a) and -3-thiones (2b) respectively, which are regenerated on deprotonation. The reactions with nucleophiles of 3-alkoxy and 3-alkylthio-1,2-dithiolium salts give dealkylation products only in minor amounts. Instead, nucleophilic attack occurs on the ring (Section 3.11.4.2(iv)). A l,2-dithiolium-4-thiolate (98) readily acylates on an amine function to form a l,2-dithiolo-l,2-dithiole (99). This unusual reactivity is explained by the relative preferences for cyclic and acyclic forms of mesoionic forms <91EGP293120>. 

HC104 added dropwise to an ethanolic suspension of 2-piperidino-4-phenyl-1,3-dithiole 4-phenyM,3-dithiolium perchlorate. Y 94%. - This is the last stage of a convenient 4-step synthesis of 1,3-dithiolium salts via phenacyl dithio-carbamates. F. e. s. A. Takamizawa and K. Hirai, Chem. Pharm. Bull. 17, 1924 (1969) reactions of the products with nucleophiles cf. ibid. 17, 1931. 

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