An examination of the substitution chemistry of di-n-hexyldichlorosilane

Various nucleophiles were reacted with the substrate di-n-hexyldichlorosilane as model reactions for the substitution of two geminal Si---Cl bonds on polymer backbone repeat units. The reactants examined were chosen on the basis of steric bulk, electronic factors, and resulting stability of the product. Linear and branched alcohol nucleophiles used in conjunction with an amine proton acceptor produced disubstituted products in moderate yields, whereas bulkier reagents substituted only one silicon---chlorine bond. Due to their vastly increased nucleophilicity, alkyllithium reagents were found to have increased activity and were found to produce very high yields.     

Catalytic Asymmetric N‐Alkylation of Indoles and Carbazoles through 1,6‐Conjugate Addition of Aza‐para‐quinone Methides

Catalytic asymmetric N‐alkylation of indoles and carbazoles represents a family of important but underdeveloped reactions. Herein, we describe a new organocatalytic strategy in which in situ generated aza‐para ‐quinone methides are employed as the alkylating reagent. With the proper choice of a chiral phosphoric acid and an N‐protective group, the intermolecular C−N bond formation with various indole and carbazole nucleophiles proceeded efficiently under mild conditions with excellent enantioselectivity and functional‐group compatibility. Control experiments and kinetic studies provided important insight into the reaction mechanism.     

KF-alumina-mediated Bargellini reaction

KF-alumina was found to be an efficient base for the synthesis of sterically hindered α-substituted carboxylic acids. A series of Bargellini reactions were performed by using various substituted anilines, phenols, and thiophenols as nucleophiles with ketones in the presence of chloroform and KF-alumina as a base. All the compounds were fully characterized.