Rh/Cu-cocatalyzed Ring-opening Diborylation of Dibenzothiophenes for Aromatic Metamorphosis via Diborylbiaryls

Abstract

Here, we report a new method for aromatic metamorphosis of dibenzothiophenes into other cyclic skeletons via 2,2¤-diborylbiaryls. In the presence of bis(pinacolato)diboron and cesium fluoride, the two CS bonds of dibenzothiophenes underwent a couple of sequential borylation reactions cocatalyzed by rhodium and copper complexes to afford the corresponding 2,2¤-diborylbiaryls. As a proof-of-principle, 2,2¤-diborylbiphenyl was converted into a series of extended π-systems such as fulvenes, dibenzofuran, oxaborin, and azaborin.

One tool to bring them all: Au-catalyzed synthesis of B,O- and B,N-doped PAHs from boronic and borinic acids

“…24,25 Compared to B,N-PAHs, analogous B,O-PAHs have been largely neglected, although a first derivative, 10-hydroxy-9,10oxaboraphenanthrene, was published by Dewar et al as early as in 1960. 26 Still today, the majority of known B,O-PAHs contains the structural motif of a 9,10oxaboraphenanthrene, [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] likely due to its convenient accessibility via B-O-bond formation/electrophilic aromatic borylation sequences (Scheme 2a; compare the analogous B,N case shown in Scheme 1a). [26][27][28][29][30][31][32][33] A second class of B,O-PAHs with a reasonably large number of members are 1,2-B,O-naphthalenes.…”

Synthesis of Alkynyl Sulfides by Copper-Catalyzed Thiolation of Terminal Alkynes Using Thiosulfonates

“…Organosulfur compounds have a broad range of applications, particularly in the fields of medicinal chemistry and materials science . Recent advances in the transformations of thio groups have further enhanced the synthetic utility of organosulfurs, enabling the preparation of a wide variety of compounds via C–S bond cleavage including cross-coupling reactions . In particular, alkynyl sulfides have attracted attention as useful synthetic intermediates because they are transformable into various organosulfur compounds through diverse types of reactions including addition, ,, iodocyclization, , cycloaddition, ,, and cross-coupling reactions .…”

Copper‐Catalyzed Preparation of Alkenylboronates and Arylboronates

“…In 2017, the Yorimitsu Group reported a bimetallic Rh/Cucatalyzed ring-opening diborylation reaction of dibenzothiophenes with diboron based on transition metal-catalyzed CÀ S bond borylation [219] to access 2,2'-diborylbiaryl compounds (Scheme 46b). [220] In the presence of B 2 pin 2 and CsF, the two CÀ S bonds of dibenzothiophenes underwent a couple of sequential borylation reactions co-catalyzed by rhodium and copper complexes to afford the corresponding 2,2'-diborylbiaryls. Addition of a catalytic amount of (IPr)CuCl, could sufficiently accelerate the rhodium-catalyzed borylation reactions, whereas only Rh-PCy 3 catalyst [219b] required a long reaction time and led decomposition of the product.…”