Coupling-Spirocyclization Cascade of Tryptamine-Derived Isocyanides with Iodonium Ylides and Despirocyclization Reactions

Abstract

A cobalt­(II)-catalyzed coupling-cyclization cascade reaction between tryptamine-derived isocyanides and iodonium ylides is investigated, which allowed for the synthesis of different types of spiroindoline compounds by variation of substituents at the N1- and C2-positions in the indole skeleton. More interesting is that the spiroindoline products could undergo despirocyclization in the presence of amines, enabling efficient construction of enamine compounds.

Silylacetate-promoted addition reaction of isocyanides to nitrones: effective synthesis of C(1)-carboxamide derivatives

“…Furthermore, to demonstrate the application and robustness of this method, we synthesized alkaloid alangiobussine I 31 from the reaction between 3,4-dihydro-β-carboline 2-oxide ( 5 ) and isocyanide 2i , which was derived from ( l )-triptophane. 32 To our delight, alangiobussine was obtained in 61% yield under the optimized reaction conditions (Scheme 2). Alangiobussine was successfully obtained without loss of chemical yield even when the scale was increased to 1.0 mmol.…”

Shining light on tryptamine-derived isocyanides: access to constrained spirocylic scaffolds

“…Containing an electron-rich indole ring and an electron-decient isocyanide group, their reactivity has been oen exploited in the generation of several naturally occurring and structurally complex alkaloids. [9][10][11] The isocyanide group electronically resembles a terminal alkyne, with the additional benet of higher polarizability of the p*-orbital of the isocyanide group. 2 This feature could in principle favour an intramolecular charge transfer with the electron-rich indole ring in tryptamine-derived isocyanides.…”

Rh(iii)-catalyzed selective mono- and dual-functionalization/cyclization of 1-aryl-5-aminopyrazoles with iodonium ylides

“…Therefore, it is highly desirable to develop a new route to remove the current barriers. As a continuation of the improvement in transition-metal-catalyzed C–H activation of iodonium ylides 10 and our work on developing heterocycle synthesis, 11 herein, we established an approach to construct nitrogen-containing polycycles via sequential two-fold C–H bond unsymmetrical functionalization/cyclization with iodonium ylides. Additionally, a mono C–H bond functionalization/cyclization product could be obtained (Scheme 1c).…”