Polycyclic Ring Formation Using Bis-diazolactams for Cascade Stitching

Abstract

The chemoselective reaction of donor/acceptor (D/A) and acceptor/acceptor (A/A) diazo moieties in the same molecule was examined using 3-diazo-1-(ethyl 2-diazomalonyl)indolin-2-one under rhodium(II) catalysis. The metallo carbenoid derived from the D/A diazo group is preferentially formed and undergoes selective CH, NH, and OH insertion reactions, cyclopropanation, cyclopropenation, sulfur ylide formation/2,3-sigmatropic rearrangement, as well as nitrogen ylide formation followed by azetidine ring expansion. The initial reaction can be paired with a subsequent tandem cascade sequence involving dipole formation/cycloaddition in either an intra- or intermolecular sense to generate polycyclic N-heterocycles in one pot, with the formation up to three new rings in a single operation. Excellent diastereoselectivity was observed in the intramolecular cycloaddition reaction producing 5 to 7-membered rings.

Electrooxidation enables highly regioselective dearomative annulation of indole and benzofuran derivatives

“…As compared with this, these types of methodologies failed to provide a practically efficient route toward biologically valuable six to bigger-membered heterocycle-fused indolines (Fig. 1a) [39][40][41][42][43][44] . Therefore, it is highly appealing to develop efficient approaches to allow for their preparation.…”

Cooperative Catalysis for the Highly Diastereo‐ and Enantioselective [4+3]‐Cycloannulation of ortho‐Quinone Methides and Carbonyl Ylides

“…[6] Carbonyl ylides generated from carbonyl compounds and a rhodium carbene complex are classically considered as highly reactive transient species and are widely employed in 1,3-dipolar cycloaddition reactions with a wide variety of 2psystems. [7,8] However, their reactivity with 4p-systems is still underexplored due to the challenges associated with entropy factors and strain aspects in the formation of seven-membered rings. [9,10] Ortho-quinone methides (o-QMs) feature a particularly reactive 4p-system and have increasingly been exploited as versatile synthetic intermediates for the construction of complex heterocycles.…”

Interception of Secondary Amide Ylide with Sulfonamides: Catalyst-Controlled Synthesis of N-Sulfonylamidine Derivatives

“…Its transformations have also attracted considerable attention from chemists who wish to create useful functional groups, such as aldehydes, imines, etc . In recent years, metal–carbene activation of amides has been validated as a powerful platform for the transformation of amides. , Specifically, tremendous efforts have been devoted to the diversification of tertiary amides for the synthesis of various cycloaddition products . In sharp contrast, the transformation of secondary amides with metal–carbenes has been less explored due to the unambiguous N–H insertions of amides .…”