Intramolecular Aminocyanation of Alkenes by NCN Bond Cleavage

Abstract

A metal-free, Lewis acid promoted intramolecular aminocyanation of alkenes was developed. B(C 6 F 5 ) 3 activates N-sulfonyl cyanamides, thus leading to a formal cleavage of the NÀCN bonds in conjunction with vicinal addition of sulfonamide and nitrile groups across an alkene. This method enables atom-economical access to indolines and tetrahydroquinolines in excellent yields, and provides a complementary strategy for regioselective alkene difunctionalizations with sulfonamide and nitrile groups. Labeling experiments with 13 C suggest a fully intramolecular cyclization pattern due to the lack of label scrambling in double crossover experiments. Catalysis with Lewis acid is realized and the reaction can be conducted under air.

Catalytic Intermolecular Carboamination of Unactivated Alkenes via Directed Aminopalladation

“…However, despite extensive effort over the past decades, realizing a catalytic intermolecular carbo­amination of unactivated alkenes has remained a challenge. During the past decade, Wolfe and others have developed a series of palladium(0)-catalyzed intra­molecular carbo­amination methods by using alkene substrates with a tethered nitrogen nucleo­phile (Scheme A) . These transformations are an effective means of accessing various aza­hetero­cycles.…”

Electrophilic Cyanation of Boron Enolates: Efficient Access to Various β‐Ketonitrile Derivatives

“…We initially chose NCTS, which has been employed in electrophilic cyanation reactions promoted by boron Lewis acids,, as a cyanating reagent to investigate the cyanation of boron enolates derived from chalcone ( 1 a ; Table ) . A brief screening of borane derivatives revealed that the boron enolate prepared using 9‐borabicyclo‐[3.3.1]nonane (9‐BBN) reacted smoothly with NCTS in THF at ambient temperature, thus affording the desired product 2 a in 84 % yield, along with a small amount of the boron complex 2 a ′ as a by‐product (entry 1) .…”

Progress in the Chemistry of Tetrahydroquinolines

“…Douglas and co-workers developed an efficient method allowing the synthesis in excellent yields of the 2,2-disubstituted tetrahydroquinoline 122 via a Lewis acid-promoted intramolecular aminocyanation of alkenes from readily available cyanamide 121 (Scheme ). This transformation may proceed through activation of N -sulfonyl cyanamide group by the Lewis acid B­(C 6 F 5 ) 3 , followed by intramolecular nucleophilic attack of the alkene to the central cyanamide with cleavage of the N–CN bond and vicinal addition of the sulfonamide and nitrile groups across the alkene.…”