Pd‐Catalyzed Cascade Metallo‐Ene Cyclization/Metallo‐Carbene Coupling of Allenamides

Abstract

A highly efficient palladium‐catalyzed cascade metallo‐ene/metallo‐carbene coupling reaction was developed to produce 2,3‐dihydropyrrole derivatives in high yields. In this transformation, two new Csp3−Csp2 and Csp2−Csp2 bonds were constructed in one‐pot. The alkene was one of the most easily functionalized groups, making it possible for these molecules to be transformed into more complex molecules. More importantly, the final product possessed an attractive 1,3,8‐trienes scaffold, which was difficult to be synthesized.

Recent Advances in the Synthesis of Five‐membered Nitrogen Heterocycles Induced by Palladium Ions and Complexes

“…An efficient, high-yielding synthesis of 2,3-dihydropyrroles catalyzed by PdCl 2 with ligand L7 [1,1'bis(diphenylphosphano)ferrocene, dppf] has been developed. [28] Starting material 6 and N-para-tosylhydrazones partook in a cascade metallo-ene cyclization/metallo-carbene coupling reaction furnishing the products in low to high yields in one pot (Scheme 16). During these transformations, both C(sp 3 )À C(sp 2 ) and C(sp 2 )À C(sp 2 ) bonds were formed.…”

Palladium‐Catalyzed Cycloisomerization of 1,6‐Allene‐Ene via [1,8]‐Sigmatropic Hydrogen Shift of Allylic C−H

“…On the basis of our recently developed cyclization of allenamides, [52][53][54][55][56][57][58][59][60] we envisioned a plausible Csp 3 -H bond activation of the allylic position, which might undergo hydrogen atom transfer to deliver pyrroline derivates as shown in Scheme 1D. However, the chemo-and regio-selectivity and low BDE distinction between the old and new CÀ H bond are the main challenging.…”

Palladium catalyzed molecular cascades for the synthesis of ethyl 2-methyl-2-(4-methyl-3-(morpholinomethyl)-2-oxopent-3-en-1-yl)-1-oxo-1,2,3,4,5,6-hexahydro-3aH-indene-3a-carboxylate

“…More importantly, the final product possesses an attractive 1,3,8-trienes scaffold, which is difficult to be synthesized (Scheme 1b). 5 Within this panorama, Grigg's group has provided several examples of tri-and tetra-molecular queuing cascades. 6,7 Typically, a 4-component cyclization anion-cascade reaction requires a starting species that undergoes oxidative addition affording an organopalladium(II) intermediate.…”