A copper-catalyzed coupling reaction of vinyl halides and carbazates: application in the assembly of polysubstituted pyrroles

Abstract

CuI-catalyzed coupling of vinyl halides with carbazates gives N-protected N-alkenylhydrazines, which are condensed with ketones under acidic conditions to give polysubstituted pyrroles. The pyrrole synthesis may go through a similar mechanism with Fischer indole synthesis, which involves a [3,3]-sigmatropic rearrangement and other reactions.

Generation and Rearrangement of N,O‐Dialkenylhydroxylamines for the Synthesis of 2‐Aminotetrahydrofurans

“…[7][8][9] We initiated our studies towards the generation of N,Odialkenylhydroxylamines 6 for the synthesis of 2-aminotetrahydrofurans 8 through the development of conditions for the N-alkenylation of N-Boc-siloxyamine 1.U sing previous studies of hydrazodiformates as as tarting point, coppercatalyzed conditions for the N-alkenylation of 1 were optimized and the reaction was determined to work best in the presence of 10 mol %CuI and DMEDA(N,N'-dimethylethylenediamine) (Scheme 2). [10,11] Thescope of the synthesis of 3 was then investigated and shown to work well for both cyclic and linear E-alkenyliodides 2.C yclohexenyl-and cycloheptenyl N-siloxyenamines 3a and 3b were prepared in excellent yield and acetal-substituted cyclohexenyl enamine 3c and b- tetralone-derived 3d were also shown to be easily accessible. Heterocyclic alkenyl iodides were tolerated by the transformation for the preparation of N-siloxyenamines 3e and 3f, as well as 3g and 3h with more complicated substitution patterns.…”

Recent Applications on Dual-Catalysis for C–C and C–X Cross-Coupling Reactions

“…On the other hand, considerable attention has also been given to copper catalysis in the field of cross-coupling reactions during the last decade, owing the low cost of the catalysts, good functional group tolerance, high abundance, and low toxicity. [19][20][21][22][23][24][25] Besides which, copper plays a crucial role in cross-coupling reactions, and its scope and practicality in the bond formation processes of CN, CO, CP, and CC bonds has substantially grown. Most wellknown catalytic processes use a single catalyst to achieve the desired chemical transformation.…”

Synthesis of N‐Aryl‐ and N‐Alkenylhydrazides through C(sp2)−N Bond Construction

“…Later, Ma demonstrated a copper‐catalyzed N ‐alkenylation of monosubstituted N ‐acylhydrazines (Scheme 56). [93] There are three features of Ma's methodology: 1) The optimized conditions were obtained by employing CuI as a catalyst and Cs 2 CO 3 as a base in DMSO with no extra ligand needed. 2) In addition to iodine, β‐bromostyrenes are also practical coupling partners in vinyl hydrazidation reactions.…”