Toluene, 4-isocyano

In 2007, Tron and Zhu reported the multicomponent synthesis of 5-iminoox-azolines (42) starting from a,a-disubstituted secondary isocyano amides (41), amines, and carbonyl components (see Fig. 15) [155]. The reaction presumably follows a similar mechanism as in the 2,4,5-trisubstituted oxazole MCR (described in Fig. 11) however, because of the absence of a-protons at the isocyano amide 41, the nonaromatized product is obtained. As in the 2,4,5-trisubstituted oxazole MCR, toluene was found to be the optimal solvent in combination with a weak Brpnsted acid. The reaction was studied for a range of aldehydes and secondary amines. In addition, a variety of functionalities such as acetate, free hydroxyl group, carbamate, and esters are tolerated. Clean conversions were observed for this MCR as indicated by NMR analysis of the crude products (isolated yield 50-68%). The... 

The same equipment is used as described in the procedure in Section B. The flask is charged with Fe(CO)4(2-CNC6H3Me2-l,3)(1.79g, 6.0mmol), CoCl2-2H20 (0.034 g, 0.2 mmol), and toluene (30 mL), and the mixture is heated to 85 °C with stirring. To the hot solution is added 2-isocyano-l, 3-dimethylbenzene (1.57 g, 12.0 mmol). It is crucial to add the isocyanide to the hot solution. Otherwise, catalyst deactivation (believed to be due to isocyanide polymerization) occurs. This results in sluggish and incomplete reaction.4,12... 

Tosylmethyl isocyanide anion reacts with a,P-unsaturated esters, ketones or sulfones with loss of toluene-sulfinate. Isocyano-acetates react with a,P-unsaturated nitro-compounds with loss of nitrous acid. 

Finally, in this category there must be included cyclisations of the benzylic anions derived from ortho-isocyano-toluenes the scheme shows this route in its simplest form. However, the synthesis is very flexible, for example the initial benzylic anion can be alkylated with halides or epoxides before the ring closure, thus providing 3-substituted indoles and, additionally, the final A -hthioindole can be A -alkylated by adding a suitable electrophile before work-up. ... 

Stirrer-heater device. When the reaction mixture has reached 85 °C, 2-isocyano-1,3-dimethylbenzene (0.786 g, 6.0 mmol) is added to give an immediate green coloration. Vigorous CO evolution occurs for a period of 10 min. The completion of the reaction is indicated by the cessation of CO evolution, but is best confirmed by IR spectroscopy (Table I). The reaction mixture is cooled to 0 °C, filtered to remove the catalyst, and then passed down a short silica gel column ( 20g, wrapped in foil to minimize photochemical decomposition) in order to remove any remaining traces of catalyst. Portions of toluene may be used as eluent. The solvent is removed under reduced pressure to give the product as a yellow, crystalline solid. Yield 2.12 g (88%). This material is sufficiently pure for most purposes, but it may be recrystallized from dichloromethane-pentane to give the analytically pure product. 

Pyrroles.—Formation. Toluene-p-sulphonyl-alkyl isocyanides react with electron-poor olefins to furnish pyrroles thus compound (279) and methyl cinnamate give the ester (280). Treatment of the isocyano-ester MeCH=C(NC)C02Et with Li" CH(NC)C02Et affords the pyrrole derivative (281). A series of amino-nitriles (282 R = alkyl, Ph, etc.) has been prepared by the action of... 

---