Lewis acid-promoted [2 + 2] cycloadditions of alkenes with aryl ketenes.

Stereoselective Lewis acid mediated (3+2) cycloadditions of N-H- and N-sulfonylaziridines with heterocumulenes.

Alkyl and aryl isothiocyanates and carbodiimides are effective substrates in (3+2) cycloadditions with N-sulfonyl-2-substituted aziridines and 2-phenylaziridine for the synthesis of iminothiazolidines and iminoimidazolidines. Additionally, the stereoselective (3+2) cycloaddition of N-H- and N-sulfonylaziridines with isothiocyanates can be accomplished, allowing for the synthesis of highly enant...

Development of transition-metal-catalyzed cycloaddition reactions leading to polycarbocyclic systems*

We present a compilation of methodologies developed in our laboratories to assemble polycyclic structures containing smalland medium-sized cycles, relying on the use of transition-metal-catalyzed (TMC) cycloadditions. First, we discuss the use of alkylidene cyclopropanes (ACPs) as 3C-atom partners, in particular in their Pd-catalyzed (3 + 2) cycloadditions with alkynes, alkenes, and allenes, re...

Asymmetric synthesis of highly substituted beta-lactones by nucleophile-catalyzed [2+2] cycloadditions of disubstituted ketenes with aldehydes.

Enantioselective formal [2+2] cycloaddition of ketenes with nitroso compounds catalyzed by N-heterocyclic carbenes.

Chiral N-heterocyclic carbenes were found to be efficient catalysts for the formal [2+2] cycloaddition reaction of alkyl(aryl)ketenes and nitroso compounds to give the corresponding 1,2-oxazetidin-3-ones in moderate to good yields with high enantioselectivities. Reductive ring-opening of the oxazetidinones give the corresponding α-hydroxy acid derivatives in good yields.

Trialkylamine-mediated intramolecular acylation of alkenes with carboxylic acid chlorides.

Trialkylamine-mediated intramolecular cyclization of pent-4-enoyl chlorides was studied. Substitution with a tertiary alkyl group at the 2-position gave cyclopent-2-en-1-ones, while substitution with an aromatic group gave enol esters, which were formed by O-acylation of initially formed 3-chlorocyclopentanones with ketenes.