Efficient Modular Synthesis of Substituted Borazaronaphthalene

Abstract

A highly efficient modular synthetic method for BN-fused polycyclic aromatic hydrocarbons (PAHs) composed of a borazaronaphthalene core along with multiple functionalized sites is reported. The halogenated 2,1-borazaronaphthalene cores are constructed through a ring-closing reaction between o-ethynylaniline derivatives and boron halides. The controllable halogen substituents make further derivatization of 2,1-borazaronaphthalene cores feasible by using metal-catalyzed cross-coupling reactions. On the basis of the carefully designed precursors, various functional aromatic rings can be fused to the azaborine core via a one-pot nucleophilic tandem reaction, affording previously inaccessible PAHs in moderate yields.

Regioselective Diversification of 2,1-Borazaronaphthalenes: Unlocking Isosteric Space via C–H Activation

“…The 2,1-borazaronaphthalene core is one of the most prominent azaborine systems, highlighted by robust synthetic methods and several strategies for derivatization. 3 Furthermore, the potential bioisosteric viability of this specific system has been recently demonstrated in comparisons with a β-blocker 4a and phosphodiesterase 10A inhibitors. 4b …”

Late-stage functionalization of BN-heterocycles

“…Using a bottom-up synthesis, Pei incorporated a bromine atom at the C4 position that serves as a handle for cross-coupling to afford a triaryl substituted BN-naphthalene core 74 (Scheme 36a). 35 Cross-coupling of bisbrominated 49 or mono-C6-brominated 51 with aryl-BF 3 K reagents affords the corresponding C3,C6 substituted naphthalenes (Scheme 36b and c). 26 The reactions depicted in Scheme 36b and c can also be performed with alkenyl-BF 3 K reagents (cf.…”

BN‐Embedded Tetrabenzopentacene: A Pentacene Derivative with Improved Stability

“…Then, 3 reacted with 1,2‐diiodobenzene through a Sonogashira coupling reaction to afford 4 in 51 % yield. After a deprotection reaction with trifluoroacetic acid, the resulting diamine 5 further reacted with dibromophenylborane in a one‐pot nucleophilic tandem reaction to generate the precursor 6 , in 45 % yield, for the photocyclization reaction. After irradiating 6 with 254 nm ultraviolet (UV) light, its C−I bonds were broken by a radical mechanism to induce the cyclization reaction, whereas the solvent, as a hydrogen donor, reduced the C−Br bond to provide BNTBP in 65 % yield.…”