Metal-Free Synthesis Of Allylic α-Aminonitrile And Intramolecular Carbocyanation Of Alkenes

Efficient strategies to form carbon-carbon bond become a central theme in thefiled of organic chemistry, among them, the generation of an all-carbon-substitutedquaternary center represents a great challenge. α-Aminonitriles are exceptionallyversatile intermediates in synthetic chemistry and also proposed as being prebioticprecursors to porphyrins, corrins, and nicotinic acids. The widely used strategy toaccess α-aminonitriles bearing an all-carbon-substituted quaternary center is throughthe reactions of deprotonated α-aminonitriles from α-aminonitriles with anα-hydrogen under strong base condition and other electrophilic reagents, but thepresence of strong base will limit functional group compatibility, so the developmentof efficient routes to access α-aminonitriles with an quaternary center under mildreaction conditions is very important.The metal-catalyzed carbocyanation reactions of alkenes are powerful tools forpreparing nitriles incorporating an β-quaternary center. However, this approachrequires harsh reaction conditions and has limited reaction models and functionalgroup compatibility. Herein, we have developed a metal-free catalytic intramolecularcarbocyanation reaction of alkenes using the synthesized α-aminonitriles as substrates,which provides facile access to nitriles incorporating β-quaternary carbon centers.This thesis includes the following contents:(1). Synthesis of allylic-substituted cyclic α-Aminonitriles via allylic alkylationreactions with Morita–Baylis–Hillman adducts under mild conditions, utilizinglewis base1,4-Diaza[2.2.2]bicyclooctane(DABCO) as an organocatalyst and1,2-dihydro-quinoline/isoquinoline analogues as starting materials, which has goodfunctional group tolerance. A novel tandem Strecker-allylic alkylation reaction withaldehydes, amines, and electron-deficient allenes has been developed, which providesa synthetic route for the preparation of chain α-aminonitriles bearing anallylic-substituted functional group. The starting materials are readily available andthe operation is easy to handle.(2). A metal-free catalytic intramolecular carbocyanation reaction of alkenes has been achieved, the acylcyanation and alkenylcyanation of the alkenes have beeninvestigated respectively. And this newly developed metal-free catalyticintramolecular carbocyanation reaction of alkenes has been proved to be widelyapplicability through investigation on substrate scope and different reaction models,which represents potential application prospect. The asymmetric version of thistransformation and the proposed reaction mechanism have been investigated too.