Stereoselective Synthesis of Novel 2-Alkenyl-2,3,4,5-tetrahydro-1,4-epoxy-1-benzazepines and 2-Alkenyl-2,3,4,5-tetrahydro-1H-1-benzazepin-4-ols

Abstract

New series of polyfunctionalized 2,3,4,5-tetrahydro-1,4-epoxy-1-benzazepines and 2,3,4,5-tetrahydro-1<i>H</i>-1-benzazepin-4-ols substituted at C2 with 2-methylprop-1-enyl, (<i>E</i>)-styryl, and (<i>E</i>)-pent-1-enyl were synthesized starting from the corresponding <i>N</i>-alkenyl-substituted [prenyl, <i>trans</i>-cinnamyl, (<i>E</i>)-hex-2-enyl] 2-allylanilines by a three-step sequence consisting of selective oxidation of aromatic secondary amines, intramolecular nitrone–olefin 1,3-dipolar cycloaddition, and reductive cleavage. The intramolecular 1,3-dipolar cycloaddition is stereoselective favoring the <i>exo</i>-cycloadducts (ratio <i>exo</i>/<i>endo</i> 2–3:1). The stereochemistry was determined by exhaustive NMR analysis and X-ray diffraction.