Dual Rh(II)/Pd(0) Relay Catalysis Involving Sigmatropic Rearrangement Using N-Sulfonyl Triazoles and 2-Hydroxymethylallyl Carbonates

Abstract

Dual Rh­(II)/Pd­(0) relay catalysis of N-sulfonyl triazoles and 2-hydroxymethylallyl carbonates has been developed, which affords N-sulfonyl pyrrolidines in moderate to good yields with high diastereoselectivities. The reaction proceeds via a relay mechanism involving O–H insertion onto the α-imino Rh­(II)–carbene, [3,3]-sigmatropic rearrangement, dipole formation through Pd(0)-catalyzed decarboxylation, and intramolecular N-allylation, leading to the formation of multiple bonds in a one-pot operation.

Tandem One-Pot Synthesis of 2H- and 3H-Pyrroles Enabled by Dual Rh(II)/Pd(0) Catalysis

“…We also disclosed a dual Rh(II)/Pd(0) relay catalysis using N-sulfonyl-1,2,3-triazoles 1 and hydroxymethylallyl carbonates 2 to afford N-sulfonylpyrrolidines 3 (Scheme 1A). 9 Considering that N-sulfonyl- Recently, we reported a tandem one-pot synthetic method for 2-acyl-substituted NH-pyrroles 4, involving tandem Rh(II)/Pd(0) catalysis using N-sulfonyl-1,2,3-triazoles 1 and hydroxymethylallyl carbonate 2 and a sequential DBU-promoted E1cB/aromatization (Scheme 1B). 10 In our continuing interest in dual Rh(II)/Pd(0)-catalyzed approaches toward valuable N-heterocycles, we wondered whether it would be possible to access 2H-pyrroles 5 and 3H-pyrroles 6 via a tandem one-pot operation starting from N-sulfonyl-1,2,3-triazoles 1 and R 2 -or R 3 -disubstituted hydroxymethylallyl carbonates 2a and 2b (Scheme 1C).…”

“…Most cases involved the reaction of Pd(II)--allyl complexes and -imino Rh(II)-carbenoids A generated from Nsulfonyl-1,2,3-triazoles, in which triazoles were used as stable nitrogen sources. We also disclosed a dual Rh(II)/Pd(0) relay catalysis using N-sulfonyl-1,2,3-triazoles 1 and hydroxymethylallyl carbonates 2 to afford N-sulfonyl pyrrolidines 3 (Scheme 1A) [9] . Considering that N-sulfonyl triazoles 1 are reliable and easily accessible nitrogen-containing starting materials, developing a strategy to access valuable 2Hand 3H-pyrrole scaffolds via dual Rh(II)/Pd(0) catalysis from Nsulfonyl triazoles would be highly desirable.…”

One-Pot Synthesis of Unprotected 2-Acylpyrroles from 1,2,3-Triazoles and 2-Hydroxymethylallyl Carbonates

“…We have also introduced the tandem one-pot synthesis of polysubstituted pyrroles using simple nitriles . With our continuing research interest in azaheterocyclic synthesis, we envisioned the regioselective one-pot synthesis of polysubstituted N H pyrroles 3 that bear an acyl group at 2-position, starting from N -sulfonyl-triazoles 1 and 2-hydroxymethylallyl carbonates 2 (Scheme B). We have developed recently the dual Rh­(II)/Pd(0) relay catalysis of 1 and 2 to afford N -sulfonyl 2-acylpyrrolidines 4 , which involves the multiple steps of rhodium-catalyzed O–H insertion, [3,3]-sigmatropic rearrangement, Pd(0)-catalyzed decarboxylation, and intramolecular N -allylation .…”