Rhodium-catalysed ortho-alkynylation of nitroarenes

Abstract

The ortho-alkynylation of nitro-(hetero)arenes takes place in the presence of a Rh(III) catalyst to deliver a wide variety of alkynylated nitroarenes regioselectively. These interesting products could be further derivatized by...

Construction of Heterobiaryl Skeletons through Pd-Catalyzed Cross-Coupling of Nitroarenes and Heterocyclic Arylborononate Esters with a Sterically Demanding NHC Ligand

“…We are interested in the coupling reactions of nitroarenes since they are cheap and readily available. Additionally, the C–N bonds of nitroarenes are relatively inert, and this would allow postsynthetic modification or stepwise coupling. − …”

Diverse reactivity of alkynes in C–H activation reactions

“…Echavarren et al recently reported Rh(III)catalyzed ortho-alkynylation of nitroarenes 106 using bromoalkyne 107 in a regioselective manner (Scheme 35). 47 Unsubstituted nitrobenzene offered a mixture of mono-and dialkynylated products in 4 : 1 ratio, whereas ortho-substituted nitrobenzene resulted in monoalkynylation. High siteselectivity was observed in the case of meta-substituted nitrobenzenes, offering functionalization at the least hindered site in the case of methyl, dimethyl and some other substituents.…”

“…Echavarren et al recently reported Rh( iii )-catalyzed ortho -alkynylation of nitroarenes 106 using bromoalkyne 107 in a regioselective manner (Scheme 35). 47…”

Tandem C/N-Difunctionalization of Nitroarenes: Reductive Amination and Annulation by a Ring Expansion/Contraction Sequence

“…Alternatively, the nitro moiety can be used to facilitate C–H functionalization reactions that decorate the aryl periphery with retention of the nitro group . Such methods include vicarious nucleophilic substitution (S N Ar H , Mąkosza reaction), oxidative nucleophilic substitution of hydrogen (ONSH) reactions, , and directed transition-metal-catalyzed C–H functionalization [Figure A­(b)]. , A valuable subclass of nitroarene functionalization reactions accomplishes both nitro group reduction and proximal C–H functionalization simultaneously, which permits annulation, as exemplified in the Bartoli indole synthesis and catalytic indole-forming methods [Figure A­(c)] . To move beyond indole synthesis, a complementary annulative approach to nitroarene C/N-difunctionalization would ideally provide a synthetically modular method for the synthesis of heterocyclic ring systems, thereby providing the synthetic chemist with control over the functionality incorporated into annulated products [Figure A­(d)].…”