Thiophosgene, cycloaddition

The reaction of tetrazole 132 with thiophosgene leads to [l,2,4]triazolo[3,4+][l,3,4]thiadiazoles 49. The reaction involves the in situ generation of aryldiazomethanes by decomposition of the tetrazole, followed by two cycloadditions (Equation 38) <1999CPA215>. 

The cycloaddition of two isothiocyanate molecules, prepared by condensation of 6-methoxy-3-pyridinamine and thiophosgene, produces a new type... 

Halo substituted compounds are scarce. 4-Chlorothiinium salts are made by elimination from the 4,4-dichloro-4H-thiin intermediate, which is usually not isolated (equation 116) (75TL2669), and the 2-chloro analogue is derived by cycloaddition of thiophosgene with a diene. 

The preparation of 2-chlorothiopyrylium salts can be accomplished by a two-component synthesis. Reaction of /ru/ij-rra/i5-1,4-diphenyl-1,3-butadiene with excess thiophosgene gives 2-chloro-3,6-diphenylthiopyry-lium chloride 102 in high yield (Scheme 7) (67ZC227). The reaction probably consists in a Diels-Alder cycloaddition, followed by elimination of HCl and hydride abstraction. When the reaction was carried out with l-phenyl-3-methyl-l,3-butadiene, the 3,5-disubstituted thiopyrylium 103 was isolated without evidence of the 4,6-disubstituted regioisomer (84AP938). 

A few examples of cycloadditions with the thiophosgene equivalent (189) have been reported (equation 94). In addition, methyl cyanodithioformate (190) has also been utilized several times as a heterodienophile (equation 95). ... 

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