Thiocarbonyl 5-Sulfides

From norbornadiene and cyclopentadiene the mono [4+2] cycloadducts are obtained. 2.3,2 Thiocarbonyl 5-Sulfides 

Thiocarbonyl 5-sulfides (thiosulfines) were postulated as intermediates and sometimes their cyclodimers, 1,2,4,5-tetrathianes, are isolated. In 1987 Huisgen and Rapp provided the first evidence for their existence. The authors generated diphenylthiocarbonyl 5-sulfide by heating 3,3,5,5-tetraphenyl-l,2,4-trithiolane 25, and intercepted the reactive diphenylthiosulfine 26 with suitable dipolarophiles, such as dicyanoacetylene to give 27 

In addition, the generated diphenylsulflde was also intercepted with the same dipo-larophiles to give the Diels-Alders cycloadducts 29 (R = -CN or -C02Me). 

Adamantanethione was also used as a dipolarophile to trap 26, and the [3+2] cycloadduct is obtained in 81 % yield. Cyclooctyne is also used as a dipolarophile for trapping diphenylthiocarbonyl S-sulfide and p-chlorodiphenylthiocarbonyl 5-sulflde. The [3+2] cycloaddition reaction of the thiocarbonyl 5-sulflde 30 with diarylsulfides 

In the reaction of tetraethoxyallene with disulfurchloride an 83 % yield of 1,2,4,5-tetrathiane-3,3,6,6-tetracarboxylate 32, the dimer of (Et02C)2C=S=S, is obtained 

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If the rearrangement is carried out in the presence of elemental sulfur, diminished yields of benzoxathiocins are obtained under these conditions, formation of thiocarbonyl 5-sulfides (thio-sulfines), which are trapped via intramolecular cycloaddition, accounts for the major products formed (Scheme 36) <92CC600). 

H shift. In some cases, e.g., methyl azidoacetate, the sulfur atom extmded in the course of the reaction is intercepted by 1 to give a thiocarbonyl 5-sulfide (thiosulfine, 33), which subsequently undergoes a 1,3-dipolar cycloaddition with 1 yielding... 

In contrast, the analogous cycloadducts of aromatic sulfines and 1 cannot be isolated. Instead, 1,2,4-trithiolane (51) is obtained in the reaction of thiobenzophenone 5toxide (50) with 2 equiv of 1 (eq 21). In this multi-step reaction, a sulfur-transfer leading to a thiocarbonyl 5-sulfide is proposed as a key step. The formation of equimolar amounts of 2,2,4,4-tetramethylcyclobutane-l,3-dione (52) indicates that in this system 1 acts as a sulfur donor. In a three-component system containing 50, 1, and ( )-cyclooctene, an episulfidation of the strained alkene is observed. ... 

Oxidation of thioketenes with peracids affords thioketene 5 -oxides (R2C=C=S=0) , a class of heterocumulenes also treated in this chapter. A review of thioketene -oxides was published in 1985. Also, alkylidenethioketenes (R2C=C=C=S) and thiocarbonyl-5 -sulfides (R2C=S=S) are known. The higher homologue, CH2=C=C=C=S, is generated by irradiation of matrix isolated 2,5-diiodothiophene. ... 

The benzotrithioles (127) have been prepared for R = Pr and OMe and the X-ray structure has been determined in the latter case [95CL321]. The hindered 1,2,4-trithiolane (128), a thiocarbonyl sulfide cycloaddition product, has been formed as a byproduct [95HCA1499]. The benzodithiatellurole and benzothiaselenatellurole (129) have been prepared and the former can be further converted into the spiro compound (130) [95TL587]. 

A soln. of bis[isopropyl(thiocarbonyl)] sulfide in hexane added to a soln. of freshly prepared Na-benzeneselenolate in 3 1 dichloromethane/methanol at 0°, and stirred for 30 min - Se-phenyl 2-propanecarboselenothioate. Y 77%. F.e., also from thiocar-boxylic acid chlorides (with selenolates or silyl selenides), and reactions s. S. Kato et al.. Bull. Chem. Soc. Japan 61, 3931-J2 (1988). 

The 1,3-dipolar systems involved in the cycloaddition reaction with cumulenes include azides, nitrile oxides, nitrile imines, nitrones, azomethine imines and diazo compounds. However, some 1,3-dipolar systems are also generated in the reaction of precursors with catalysts. Examples include the reaction of alkylene oxides, alkylene sulfldes and alkylene carbonates with heterocumulenes. Carbon cumulenes also participate as 1,3-dipols in [3+2] cycloaddifion reactions. Examples include thiocarbonyl sulfides, R2C=S=S, and l-aza-2-azoniaallenes. 

Alkylidenethioketenes and thioketene 5-ylides (R2C=C=S=CH2) are also described in this chapter. The latter were trapped by an intramolecular cycloaddition reaction to give dithiolanes. Also, propadieneselon, CH2=C=C=Se, is described in this chapter. The unusual extended system, ArN=C=C=C=S, was recently generated by flash vacuum thermolysis ". Thiocarbonyl- -sulfides are treated as Thiosulfines in Section 4.2.2. 

Application of radical reactions to organic synthesis has recently received much atrendon, and various important reacdons have been discovered in this field. Alkyl halides, sulfides, seleniJes, and thiocarbonyl compounds have been used as precursors to alkyl radicals. Some examples are illustrated in Scheme 7.18. ... 

Common synthesis of disulfonium dications involves formation of a S-S bond by oxidative coupling of two sulfide moieties. Involving for oxidative generation of S-S bond, thiocarbonyl compounds can lead to new-type dications containing disulfide moieties between two positively charged fragments. There are several disulfide dications of this type derived from thioureas, thiocarbon-ates and thioketones as well as selenium derivatives.137 148... 

Another interesting example of a photochemi-cally induced domino process is the combination of the photocyclization of aryl vinyl sulfides with an intramolecular addition as described by Dittami et al. [901 as intermediate a thiocarbonyl ylide can be assumed. The domino-Norrish I-Knoevenagel-allyl-silane cyclization developed by us allows the efficient stereoselective formation of 1,2-trans-subsituted five- and six-membered carbocycles.1911 A photochemical cycloaddition of enamino-aldehydes and enamino-ketones with the intermediate formation of an iminium salt followed by addition to allylsilanes gives access to novel bicyclic heterocy-des. New examples of photochemically induced... 

This is often achieved from 1,4-dicarbonyl compounds in a procedure similar to that used to form furans but using phosphorus pentasulfide, or Lawesson s reagent (see below), to cause a transposition from carbonyl to thiocarbonyl groups, prior to cyclization and loss of hydrogen sulfide (Scheme 6.37). 

Dihydrobenzoxazin-3-one 20 and its A -methyl derivative 165 can be converted into the corresponding thiocarbonyl compounds 166 and 167 using Lawesson s reagent <1988M1439> or phosphorus(v) sulfide <2005H(65)579> (Equation 9). 

Thiocarbonyl ylides (1) belong to tbe family of sulfur-centered 1,3-dipoles cbaracterized by tbe presence of two sp C atoms attached to tbe sulfur atom. Formal replacement of one of the C atoms by heteroatoms such as NR3, O, and S lead to the other representatives of the family, namely, thiocarbonyl S-imides (2), S-oxides (sulfines) (3), and S-sulfides (thiosulfines) (4), respectively. 

As early as 1969, Block and Corey (73) observed the photochemical transformation of divinyl sulfide 37 to a mixture of isomeric cyclization products (39 and 40) (Scheme 5.13). A pathway involving the cyclic thiocarbonyl ylide 38 was proposed. A theoretical study concerning the nature of intermediates in the photochemical cyclization of divinyl sulfides was recently carried out (74). Several examples are known in which the vinyl group is part of an aromatic system. 

Nitrogen-containing heteroaromatic compounds react with (chloromethyl)[(tri-methylsilyl)methyl] sulfide in the presence of CsF to afford fused 1,3-thiazolidines of type 130. These compounds are the result of a formal [3 + 2] cycloaddition of the parent thiocarbonyl ylide la across the C=N bond (170). In these cases, the formation of the five-membered cycloadduct is believed to occur in two steps via an intermediate onium ion. 

Similar to ethers and carbonyl compounds, sulfides or thiocarbonyl groups interact with metal carbene to generate the corresponding ylides. These ylides undergo similar subsequent reactions as their oxygen counterparts (Figure 4). 

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