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A systematic report on Lewis base-catalyzed cycloadditions of alkynyl ketones with N-tosylimines to synthesize azetidines and pyrrolidines is presented. The nitrogen heterocyclic compounds obtained from the reactions exhibited interesting biological and pharmacological properties.

A simple and highly efficient method for the rearrangement of bromohydrins mediated by Et2Zn to synthesize carbonyl compounds was described. Various β-bromo alcohols were treated with 0.6 equiv of Et2Zn to form a zinc complex in CH2Cl2 at room temperature for 2 h, followed by 1,2-migration to give the corresponding carbonyl compounds. This remarkable and clean rearrangement is general for acyclic and cyclic bromohydrins, and a variety of ring-expansive and -contractive carbonyl compounds were obtained in good to excellent yields according to the feature of the starting bromohydrins. The functional group tolerance of organozinc reagents in this reaction will be useful in organic synthesis. The scope and limitations of this rearrangement process were also investigated. [ABSTRACT FROM AUTHOR]

A new and efficient methodology has been developed for the synthesis of β-diketones from aromatic α-bromo ketones in the presence of Furukawa reagent under mild conditions. The present transformation is proposed to proceed via a Reformatsky-type reaction of α-bromo ketones, followed by C-C bond sigmatropic rearrangement of the aldolate intermediate to give β-diketones in moderate to good isolated yields, while aliphatic α-bromomethyl ketones resulted in the formation of 2,4-disubstituted furans or cis-1,2-disubstituted cyclopropanols in moderate yields. The scope of this process was investigated, and a tentative mechanism was proposed. [ABSTRACT FROM AUTHOR]