Copper‐Catalyzed Enantioselective Doyle–Kirmse Reaction of Azide‐Ynamides via α‐Imino Copper Carbenes

Abstract

[2,3]‐Sigmatropic rearrangement reaction involving sulfonium ylide (Doyle–Kirmse reaction) generated from metal carbenes represents one of the powerful methods for the construction of C(sp3)−S and C−C bonds. Although significant advances have been achieved, the asymmetric versions via the generation of sulfonium ylides from metal carbenes have been rarely reported to date, and they have so far been limited to diazo compounds as metal carbene precursors. Here, we describe a copper‐catalyzed enantioselective Doyle–Kirmse reaction via azide‐ynamide cyclization, leading to the practical and divergent assembly of an array of chiral [1,4]thiazino[3,2‐b]indoles bearing a quaternary carbon stereocenter in generally moderate to excellent yields and excellent enantioselectivities. Importantly, this protocol represents a unique catalytic asymmetric Doyle–Kirmse reaction via a non‐diazo approach and an unprecedented asymmetric [2,3]‐sigmatropic rearrangement via α‐imino metal carbenes.

Synthesis of Cyclopenta[b]indoles via Rhodium‐Catalyzed Cascade Migration‐Annulation of 1‐Sulfonyl‐1,2,3‐triazoles and Indoles

“…Generated from 1-sulfonyl-1,2,3-triazole, α-imino rhodium carbene was utilized as 1,3-dipole in construction of various ring systems. [6][7][8][9] Intramolecular group migration of carbene is an effective strategy to produce multiple-functionalized zwitterion. [10] Our group developed a migration-annulation strategy to synthesize valuable (hetero)cyclic compounds.…”

Synthesis ofN-(acyloxy)-N-alkynylamidesviageneration of “C2” from hypervalent alkynyliodane and a weak base

“…1). 1,2 We developed transition metal-promoted molecular transformations of ynamides for the synthesis of valuable compounds, including biologically active natural products. 3 In the half century since Viehe et al first reported the synthesis of ynamides in 1972, 4 ynamides with various electron-withdrawing groups and substituents have been synthesized.…”

Synthesis of 3-aminoquinolines from α-imino rhodium carbenes and 2-aminobenzaldehydes

“…6 Nowadays, annulation of α-imino rhodium carbenes has emerged as one of the most versatile methods for the construction of various nitrogen-containing heterocycles. [7][8][9][10][11] In continuation of our interest in the chemistry of α-imino rhodium carbenes and heterocycle synthesis, the synthesis of 3-aminoquinolines via rhodium-catalyzed transannulation of 1-sulfonyl-1,2,3-triazole with 2-aminobenzaldehyde was designed (Scheme 1C). In this proposal, N-H insertion of rhodium carbene with 2-aminobenzaldehyde was followed by cyclization and aromatization.…”

“…6 Nowadays, annulation of α-imino rhodium carbenes has emerged as one of the most versatile methods for the construction of various nitrogen-containing heterocycles. 7–11…”

“…Therefore, TCE was selected for further optimization of the rhodium catalyst. Common rhodium(II) dimers could catalyze the reaction and produce the target product 3a in 63-98% yields (entries [8][9][10][11]. When Rh 2 (adc) 4 was used, the reaction time was reduced to 16 h and the yield did not change significantly compared to the reaction with Rh 2 (OAc) 4 as the catalyst (entry 11).…”