B(C₆F₅)₃‐Catalyzed Cascade Reduction of Pyridines

Abstract

B(C F ) has been found to be an effective catalyst for reduction of pyridines and other electron-deficient N-heteroarenes with hydrosilanes (or hydroboranes) and amines as the reducing reagents. The success of this development hinges upon the realization of a cascade process of dearomative hydrosilylation (or hydroboration) and transfer hydrogenation. The broad functional-group tolerance (e.g. ketone, ester, unactivated olefins, nitro, nitrile, heterocycles, etc.) implies high practical utility.

Synthesis of substituted quinolines via B(C6F5)3‐catalyzed aniline‐aldehyde‐pyruvate oxidative annulation

“…Based on our findings and the related references, a plausible reaction mechanism for the present B(C 6 F 5 ) 3 ‐catalyzed aniline‐aldehyde‐pyruvate annulation reaction is depicted in Scheme . Upon heating, B(C 6 F 5 ) 3 is generated from a Lewis adduct or the hydroxy borate to activate the imine I derived from aniline 1a and aldehyde 2a , which then undergoes nucleophilic…”

“…B(C 6 F 5 ) 3 , reported in 1964, re‐emerged as a paradigm for small molecule activation in the past decade, especially as a component in frustrated Lewis pairs (FLPs) chemistry . Moreover, B(C 6 F 5 ) 3 has been successfully employed in various other transformations . One of the research hotspots is the borane‐catalyzed multicomponent reactions (MCRs).…”

Scalable and Straightforward Synthesis of All Isomeric (Cyclo)alkylpiperidines

“…ifenprodil (5) and melperone (6), as well as compounds that have reached various drug development phases (e.g. [7] Some of them relied on the use of homogeneous Rh- [13] or Ir-based, [14,15] and metalfree [16][17][18] cata-lytic systems; nevertheless, heterogeneous catalysts like Pd-C, PtO 2 , Pd(OH) 2 -C, Rh, or RuO 2 often remained more preferable. Despite their extensive use in drug discovery, synthetic accessibility of (cyclo)alkylpiperidines have remained far from being satisfactory.…”

B(C6F5)3‐Catalyzed Reduction of Cyclic N‐Sulfonyl Ketimines

“…In 2000, Piers reported an effective hydrosilation of benzaldimines and ketimines which was catalyzed by B(C 6 F 5 ) 3 in presence of PhMe 2 SiH for the first time . From then on, the system of silane and B(C 6 F 5 ) 3 has been utilized to reduce the substituted indoles, quinolines and pyridines gradually . Actually, the basic conception of Lewis acid–base interaction has also rooted in other fields of chemistry.…”