Viehe salts

Also, the extremely labile trichloride 101 of Viehe salt 100 is reversibly and quantitatively obtained in the solid state [9]. This latter reaction is related to the solid-solid syntheses of the extremely reactive hexachloroantimonates or -phosphates (102) of the Viehe salt by its milling with antimony pentachloride or phosphorus pentachloride [9] (Scheme 11). Furthermore, the labile adduct of chlorine to benzylidene aniline is obtained at -20 °C in a solid-state reaction. 

Interestingly, the chlorination of dimethylthiocarbamoyl compounds such as 126 and 127 to give the trichloride of Viehe salt (101) can be performed as a... 

The solid-state reactions of Viehe salt (100) with primary amine functionalities (236,238,240) leads to highly substituted iminium salts in quantitative... 

The quantitative solid-state reaction of Viehe salt (100) with acetophenone (328b) by stoichiometric comilling at 0 °C leads to the highly labile iminium salt 435 and the couple product 436 [9]. A 4-cascade is assumed consisting of substitution (Cl by enol-C of328b), reaction of the oxygen with a second molecule of 100, chlorine migration, and elimination of 436. 

The 2-substituted l,3-thiazin-6-thiones 33 and 34 and 160 and 161 are accessible by reacting 3,3-dichloroprop-2-ene iminium salts (vinylogous Viehe salts) with thiobenzamide or WA -disubstituted thioureas (Scheme 11) <1997S573>. The ring closure occurs with loss of amine as the hydrochloride salt and the thiones are generated after a reaction with another thioamide molecule. 

Scheme 29). Presumably, the two additional carbons come from 1 equiv of Meldrum s acid and the hydrogens derive from the solvent. A similar Meldrum s acid with two conjugated exocyclic double bonds was obtained from the reaction of Meldrum s acid with vinylogous Viehe salt in 93% yield <1997S573>. A polymer-bonded Meldrum s acid for solid-phase synthesis was also reported <2004CHJ212>. 

Keywords Viehe salt, acetophenone, solid-solid reaction, cinnamamide... 

Acetophenone 1 (600 mg, 5.00 mmol) was cooled to 0°C in a 10-mL milling beaker and Viehe salt 2 (815 mg, 5.00 mmol) was added unter N2. Ball-milling at 0 °C was performed for 2 h. A solid mixture of product 3 and couple product 4 was quantitatively obtained. Compound 5 was obtained by treatment with water, filtration and drying. 

Solid p-nitroaniline (690 mg, 5.00 mmol) and Viehe salt 2 (815 mg, 5.00 mmol) were ball-milled at -20 °C for 1 h. Most of the HC1 escaped through the Teflon gasket that was tightened against a torque of 50 Nm. Residual HC1 was pumped off at room temperature. The yield of pure salt 3 was 1.321 g (100%). 

Keywords dimethylthiocarbamoyl compounds, chlorination, gas-solid reaction, solid-solid reaction, Viehe salt... 

Iminium salts. A/-Sily compounds afford a-silox>i chlorides are obtained. Trii induce the transformation i are more reactive than carb< Viehe salts. 

Iminium salts. N-Silyl derivatives of secondary amines react with carbonyl compounds afford a-siloxyamines. On further treatment with Me,SiCl, iminium chlorides are obtained. Trimethylsilyl triflate is superior to Me SiCl since it can induce the transformation in the cases of enolizable aldehydes. a-Chloro ethers are more reactive than carbonyl compounds, enabling the preparation of vinylogous Viehe salts. 

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