Phenyl-2-tetrazoline-5-thione

(a) Martinez-Fresneda, R Vaultier, M., Tetrahedron Lett 1989, 30, 2929. (b) Montanari, R, Gazz. Chim. Ltal. 1956, 86,406. 

Ottorino De Lucchi Universita di Venezia, Venezia, Italy 

Giovanna Delogu Istituto CNR, IATC7IPA, Sassari, Italy 

Addition Reactions. The utility of ( )-phenylsulfonyl-2-tri-methylsilylethylene in the synthesis of a-substituted allylsilanes is exemplified in eq 3 for y-hydroxyvinylsilanes, and in eq 4 in the preparation of isoprenoid structures. In these reactions the reagent functions as a Michael acceptor, but a-lithiation may compete with less nucleophilic bases such as butyllithium.  

The availability of analogous reagents bearing different atoms in the place of silicon, such as tin, boron, and chlorine as well as the alkynic homologs, is notable. Finally, the sulfide related to the title reagent merits mention.  

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Sulfur Nudeophile. The nucleophilic nature of the sulfur in 1 -phenyl-2-tetrazoline-5-thione can be utilized for the introduction of sulfur into organic compounds. Thus Mitsunobu reaction of a protected sugar with the reagent affords the substituted sugar (eq4).3... 

In a further exanple. Smith and Wan exploited the nucleophilic capability of l-phenyl-2-tetrazoline-5-thione in the Mitsunobu reaction, followed by oxidation to the sulfone with hydrogen peroxide and ammonium heptamolybdate tetrahydrate as a key step in a synthesis of the ansamycin antiobiotic, (+ )-thiazinotrienomycin-E (eq 8). Importantly, use of the phenyltetrazolylthione-derived sulfone gave an 13Z ratio of 10 1 in this coupling whereas the more conventional benzthiazole-2-thiol-derived system resulted in a selectivity of only 1.5 1 in favor of the -isomer. 

Esterification. Treatment of 1-phenyl-2-tetrazoline-5-thione with trichloromethyl chloroformate forms the symmetrical dithio-carbonate. This stable, crystalline solid acts as a novel reagent for the one-pot esterification of acids (eq 10). 

Tetrazol-5-imine, 2-methyl-dipole moment, 5, 795 (56JA4197) Tetrazoline-5-thione, 1-phenyl- C NMR, 5, 805 (77JOC3725)... 

Tetrazoline-5-thione, 1-phenyl-methylation, 5, 819 in photography, 5, 837 reactions, 5, 823 Tetrazoline-5-thiones fragmentation, 5, 810... 

Scheme 36 The reaction of organotin azides 181 and 182 with phenyl isothiocyanate (183) gives l-phenyl-4-organotin-A -tetrazoline-5-thiones 184 and 185 and their tautomers (S-organotin)-l-phenyl-5-thiotetrazoles 186 and 187. The latter are the confirmed structures of the formed intermediates that upon treatment with dilute hydrochloric acid, provide l-phenyl-A -tetrazoline-5-thione (188) [137,138]...

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