Indirect C–H Azidation of Heterocycles via Copper-Catalyzed Regioselective Fragmentation of Unsymmetrical λ³-Iodanes

Abstract

A C-H bond of electron-rich heterocycles is transformed into a C-N bond in a reaction sequence comprising the formation of heteroaryl(phenyl)iodonium azides and their in situ regioselective fragmentation to heteroaryl azides. A Cu(I) catalyst ensures complete regiocontrol in the fragmentation step and catalyzes the subsequent 1,3-dipolar cycloaddition of the formed azido heterocycles with acetylenes. The heteroaryl azides can also be conveniently reduced to heteroarylamines by aqueous ammonium sulfide. The overall C-H to C-N transformation is a mild and operationally simple one-pot sequential multistep process.

Metal/organo relay catalysis in a one-pot synthesis of methyl 4-aminopyrrole-2-carboxylates from 5-methoxyisoxazoles and pyridinium ylides

“…We mention here only recently published works on the topic. 7 4-Aminopyrrole-2-carboxylates can be synthesized by reduction of the corresponding nitro-, 1c, 4, 8 nitroso-, 9 azocompounds 10 and azides 11 or by aminodecarboxylation of alkyl 4-carboxypyrrole-2-carboxylates via the Curtius rearrangement. 3 The use of derivatives of 4-aminopyrrole-2-carboxylic acid in the synthesis of various heterocycles or ensembles with other heterocyclic systems, permits the preparation of such compounds as poly(ADP-ribosyl) polymerase-1 inhibitors, 4 dual inhibitors of Aurora kinases and cyclin dependent kinase 1, 5 androgen receptor antagonists, 6 inhibitors of the phosphodiesterase 4 enzyme.…”

Catalytic Asymmetric Epoxidation of Aldehydes with Two VANOL‐Derived Chiral Borate Catalysts

“…[20] Twoc atalysts give both high diastereo-and enantioselection. [22] Conversion of 41 a into the the ester 71 and then ring-opening with trimethylsilyl azide gives a syn-azido alcohol, which is benzoylated on oxygen, and upon azide reduction [23] undergoes benzoyl migration to give 72. [14f] Ac ase in point is the taxol side-chain 72.…”

One‐Pot C−H Functionalization of Arenes by Diaryliodonium Salts

“…[4] These reagents are generally synthesized in one or more steps,i solated, and subsequently reacted with an ucleophile.K ita and co-workers have demonstrated the efficient in situ formation of diaryliodonium salts from other iodine(III) reagents in metal-free arylations (Scheme 1b), [5] and the group of Suna has utilized the same strategy in metalcatalyzed arylations. [6] However,tothe best of our knowledge, catalytic reactions with iodonium salts or benziodoxol(on)es remain unknown. [4,7] In our long-term quest for catalytic arylation conditions, we reasoned that in situ formation of diaryliodonium salts from arenes and iodoarenes in the presence of an oxidant, followed by arylation of as uitable nucleophile under metalfree conditions,w ould constitute an important step towards this difficult goal.…”