Synthesis of Bicyclic Cyclopropylamines by Intramolecular Cyclopropanation of N-Allylamino Acid Dimethylamides.

Cyclopropylamines and substituted cyclopropylamines are important building blocks or substituents in a variety of biologically active compounds. Here, we report the facile syntheses of cyclopropylamines by Ti(II)-mediated intramolecular coupling of a terminal olefinic moiety and the N,N-dimethylcarboxamide moiety of amino acid derivatives. The products have novel and strained bicyclic structures. The yields were good (78−83%) for all three substrates with diastereomeric ratios of about 3:1.