Catalyst-dependent chemoselective insertion of diazoalkanes into the N–H/C–H/O–H/C–O bonds of 2-hydroxybenzothiazoles

Abstract

The control of chemoselective insertions of diazoalkanes with 2-hydroxybenzothiazoles is challenging. Herein, the chemoselective N-H, O-H, C-O or C-H bond insertions of diazoalkanes with 2-hydroxybenzothiazoles are achieved using B(C6F5)3, Rh2(OAc)4...

Borane‐Catalyzed, HFIP‐Assisted Carbene Insertion into Internal Alkenyl C−H Bonds under Metal‐Free Conditions

“…[4] Although metal-free CÀ H functionalization has been a challenge in organic chemistry, metal-free CÀ H insertions have attracted continuous interest, in which carbene insertion into aryl and heteroaryl CÀ H bonds has been achieved with non-metallic catalysts. [5] In this regard, B(C 6 F 5 ) 3 promoted carbene insertions to the C(sp 2 )À H bonds of phenols, [6a] indoles, [6b] and carbazoles [6c] were reported. Compared to carbene insertion into aryl, heteroaryl, and alkyl CÀ H bonds, carbene insertion into alkenyl CÀ H bonds has been challenging because alkenes usually undergo cyclopropanation with a carbene species in the presence of a transition-metal catalyst.…”

B(C6F5)3-catalyzed Wolff rearrangement/[2 + 2] and [4 + 2] cascade cyclization of α-diazoketones with imines

“…Li and coworkers 16 described related insertions into S–H bonds, while He and Koenig described analogous insertions in N–H and C–H bonds affording alkylations of carbazole derivatives, 17 while we reported the N -alkylations of triazole 18 and 2-hydroxybenzo-thiazoles. 19 Related derivatizations of diazomethanes with azide, 20 and carbonate 21 have also been reported.…”

B(C6F5)3-catalyzed cyclopropanation of 3-alkenyl-oxindoles with diazomethanes

“…[38][39][40][41][42][43] Over the past few decades, several methodologies have been developed for the construction of spirocyclopropane-oxindoles skeletons, mainly employing transition metal-catalyzed cyclopropanation of diazo compounds with alkenes. [44][45][46][47][48] Based on our previous efforts in boranes catalysis, 49,50 we envisioned borane mediated synthesis of spirocyclopropane-oxindoles. Herein, we report the facile access to such substituted 3-spirocyclopropane-oxindoles via the B(C 6 F 5 ) 3 -catalyzed cyclopropanation of 3-alkenyloxindoles with diazomethanes.…”