Recent progress in the chemistry of allenes

Allenes are important compounds in organic and synthetic organic chemistry and therefore a large number of studies on their synthesis and reactions have been reported so far. We report the most recent methods for the synthesis of allenes, including optically active forms and fluorinated and gem-difluorinated allenes, in this paper. Reactions such as nucleophilic addition of allenes were classified and discussed in details according to the nature of the nucleophile either oxygen, nitrogen, carbon or sulfur, whereas, inter- and intra-molecular cycloadditions reactions with a variety of unsaturated functionality were separately discussed. A collection of some useful reactions such as coupling reactions of allenes mediated by organometallic reagents, intramolecular cyclization of allenes with tethered amines, asymmetric dihydroxylation, and epoxidation of allenes are also included.