Ring-Opening of Vinylcyclopropane-1,1-dicarboxylates by Boronic Acids under Ligandless Palladium Catalysis in Neat Water

We report a highly efficient ring-opening reaction of vinylcyclopropanes by boronic acids in water, using palladium nanoparticles formed from Pd­(OAc)₂ under ligandless conditions. Unsubstituted vinylcyclopropanes provide linear addition products with high selectivity, while a switch in regioselectivity to branched products is observed for aryl-substituted vinylcyclopropanes

Controlled Oxidation of Pyrroles: Synthesis of Highly Functionalized γ‑Lactams

The oxidation of pyrroles usually leads to uncontrolled polymerization and decomposition. To overcome this problem, the controlled oxidation of substituted pyrroles with Dess-Martin periodinane is reported. This strategy yields a range of 5-aroyloxypyrrolinones

The Diastereoselective Synthesis of Pyrroloindolines by Pd-Catalyzed Dearomative Cycloaddition of 1-Tosyl-2-vinylaziridine to 3‑Nitroindoles

An efficient, diastereoselective synthesis of densely functionalized pyrroloindolines is reported. The reaction proceeds via cycloaddition of a vinylaziridine-derived Pd-stabilized 1,3-dipole to electron-deficient 3-nitroindoles. The reactions give the <i>trans</i> diastereoisomer with high selectivity; however, when a 4-substituent is present on the indole ring, a reversal of diastereoselectivity is observed

Synthesis of Nitrogen-Substituted Methylenecyclopropanes by Strain-Driven Overman Rearrangement of Cyclopropenylmethyl Trichloroacetimidates

Nitrogen-substituted methylenecyclopropanes have been prepared by a strain-driven Overman rearrangement of cyclopropenylmethyl trichloroacetimidates. The reaction proceeds at room temperature and without the need of a transition-metal catalyst. Furthermore, it has been shown that C-3-substituted cyclopropenylmethyl trichloroacetimidates undergo a hydrolytic ring-opening reaction to form allenylcarbinols

Pd-Catalyzed Dearomative [3 + 2] Cycloaddition of 3‑Nitroindoles with 2‑Vinylcyclopropane-1,1-dicarboxylates

A <i>trans</i>-diastereoselective Pd-catalyzed dearomative [3 + 2] cycloaddition between vinylcyclopropane dicarboxylates and 3-nitroindoles has been developed. The reaction provides densely functionalized cyclopenta­[<i>b</i>]­indolines with versatile vinyl and nitro-groups. The addition of a halide additive was found to be critical for the diastereoselectivity of the reaction, which is proposed to be a result of a rapid π-σ-π interconversion between the intermediates allowing for Curtin–Hammett control. A switch in diastereoselectivity to afford products with the vinyl and nitro groups <i>cis</i> to each other is observed with a 4-substituted 3-nitroindole

Theoretical Investigation into the Palladium-Catalyzed Silaboration of Pyridines

The palladium-catalyzed silaboration of pyridines has been investigated with the use of density functional theory. The results predict a very interesting dearomatization step in the reaction mechanism which is surprisingly facile due to the formation of a very strong covalent bond between nitrogen and boron in the product. Our calculations show that the regioselectivity of the final product is governed by a mixture of electronic and steric effects, and our predicted outcomes are in agreement with the experimental results