4'-((diisopropylsilyl)methyl)-[1,1'-biphenyl]-2-carbonitrile
Introduction: The last three decades have witnessed significant progress in selective ortho-C–H functionalization of arenes. Recently, the meta-C–H bond activation has been achieved by the meticulous design of end-on nitrile coordinating template. The para-CH activation was totally unexplored domain in this exacting field. In an attempt to investigate this intriguing objective, designing of template was primarily aimed at enabling a facilitated delivery of metal through a conformationally flexible assembly. In a biphenyl skeleton, proper projection of coordinating heteroatom and installation of two sterically incumbent isopropyl moieties at Si-center effectively favored Thorpe-Ingold effect that would possibly allow closer approach of coordinating group to para-C–H bond by a domino-like ‘steric push’ of phenol derivatives. The prevalent nature of phenol moiety in natural products, pharmaceuticals, has led us to explore the recently developed directing group assisted para-CH functionalization. The easily synthesizable template shortens the route of retro-synthetic disconnection for synthesis of paracoumaric acid based natural products. Our aim is to deliver all types of functionalization at paraposition of very useful arene precursors.
Template for para-CH activation: The template has been successfully used for para-CH olefination, silylation, cyanation for phenol derivatives. Palladium catalyzed CH functionalization of phenol derivatives CC bond formation (Heck-type olefination) C-Si bond formation (Silylation with hexamethyldisilane) CCN (Cyanation with CuCN).
, Department of Chemistry