One-step synthesis of imidazoles from Asmic (anisylsulfanylmethyl isocyanide)

Substituted imidazoles are readily prepared by condensing the versatile isocyanide Asmic, anisylsulfanylmethylisocyanide, with nitrogenous π-electrophiles. Deprotonating Asmic with lithium hexamethyldisilazide effectively generates a potent nucleophile that efficiently intercepts nitrile and imine electrophiles to afford imidazoles. In situ cyclization to the imidazole is promoted by the conjugate acid, hexamethyldisilazane, which facilitates the requisite series of proton transfers. The rapid formation of imidazoles and the interchange of the anisylsulfanyl for hydrogen with Raney nickel make the method a valuable route to mono- and disubstituted imidazoles.

Strong Bases and Weak Anions in Catalytic C–H Insertion Reactions of Vinyl Carbocations

<p>Here we report the surprising discovery that high-energy vinyl carbocations can be generated under strongly basic conditions, and that they engage in intramolecular sp3 C–H insertion reactions through the catalysis of commercially available weakly coordinating anion salts. This approach relies on the unconventional combination of lithium hexamethyldisilazide base and the commercially available catalyst, triphenylmethylium tetrakis(pentafluorophenyl)borate. These reagents form a catalytically active lithium species that enables the application of vinyl cation C–H insertion reactions to heteroatomcontaining substrates.</p>

Strong Bases and Weak Anions in Catalytic C–H Insertion Reactions of Vinyl Carbocations

<p>Here we report the surprising discovery that high-energy vinyl carbocations can be generated under strongly basic conditions, and that they engage in intramolecular sp3 C–H insertion reactions through the catalysis of commercially available weakly coordinating anion salts. This approach relies on the unconventional combination of lithium hexamethyldisilazide base and the commercially available catalyst, triphenylmethylium tetrakis(pentafluorophenyl)borate. These reagents form a catalytically active lithium species that enables the application of vinyl cation C–H insertion reactions to heteroatomcontaining substrates.</p>

Synthesis of dithiafulvene–quinone donor–acceptor systems: isolation of a Michael adduct

π-Conjugated donor–acceptor systems based on dithiafulvene (DTF) donor units and various acceptor units have attracted attention for their linear and nonlinear optical properties. The reaction betweenp-benzoquinone and a 1,3-dithiole phosphonium salt, deprotonated by lithium hexamethyldisilazide (LiHMDS), gave a product mixture from which the Michael adduct [systematic name: dimethyl 2-(3-hydroxy-6-oxocyclohexa-2,4-dien-1-ylidene)-2H-1,3-dithiole-4,5-dicarboxylate], C13H10O6S2, was isolated. It is likely that one of the unidentified products obtained previously by others from related reactions could be a similar Michael adduct.