Gold-Catalyzed Bicyclic Annulations of N-(o-Alkynylphenyl)imines with α-Diazo Esters to Form 5,6-Dihydroindolo[2,1-a]isoquinolines

Abstract

One-pot synthesis of 5,6-dihydroindolo[2,1-a]isoquinolines from gold-catalyzed annulations between N-(oalkynylphenyl)imines and α-diazo esters is described. This cascade reaction involves an initial attack of the diazo ester at the imine to form cis-aziridine, followed by stereoselective [3 + 3]-annulations with the tethered arylalkyne. We have employed this new catalysis to prepare one bioactive 5,6-dihydroindolo[2,1-a]isoquinoline molecule.

Relay Zn(ii)- and Au(i)-catalyzed aziridination/cyclization/ring expansion sequence to form 3-benzazepine derivatives

“…Again, we tested the reaction on our previously used imine 1u, which still afforded the cis-aziridine 7c efficiently (eqn ( 9)). 5 Our observed trans-stereoselectivity for (2-alkynylphenyl) aldimines 1 seems to be affected by the tethered alkynyl group because unsubstituted imine 1t and the other imine 1u preferably yielded cisaziridines.…”

“…A subsequent gold-catalyzed cis-aziridine/alkyne cyclization yields 5,6-dihydroindolo [2,1-a]isoquinoline products. 5 Closely related to our work is an intramolecular cyclization of cis-aziridine/alkyne functionalities with nucleophiles to give 2,3-dihydro-1H-benzo [d]azepine, notably by Liu's work (eqn ( 5)). 6e Such cis-aziridine derivatives failed to give cyclization products in the absence of nucleophiles, manifesting the influence of aziridine geometry.…”

Recent Progress in Gold‐Catalyzed Reactions of Alkynes for the Construction of Indole Frameworks

“…The author also synthesized indolo[2,1‐ a ]isoquinoline scaffolds 127 via one‐pot cyclization of o ‐alkynylphenyl imines 124 and α ‐diazoesters 125 [95] . The reaction occurred via two steps under gold catalysis (Scheme 32).…”

“…The author also synthesized indolo[2,1-a]isoquinoline scaffolds 127 via one-pot cyclization of o-alkynylphenyl imines 124 and α-diazoesters 125. [95] The reaction occurred via two steps under gold catalysis (Scheme 32). In the first step, initial attack of the diazoester at the imine moiety led to the formation of cis-aziridine core 126 at room temperature.…”

Rh(III)-Catalyzed Reaction of 4-Diazoisochroman-3-imines with (2-Formylaryl)boronic Acids To Access a Straightforward Construction of 5H-Isochromeno[3,4-c]isoquinolines

“…5 However, the strategies based on diazo chemistry have rarely been documented for the construction of isoquinoline-fused polycyclic systems. 6 In 2017, we developed a practical method for the convenient preparation of 4-diazoisochroman-3-imines. 7 Later, we 8 and several other groups 9,10 utilized this class of cyclic α-diazo imidates as metal carbene precursors for the syntheses of diverse heterocycles.…”