Synthesis of new spiro-N-heterocycles with cyclooctane fragment from N-(1-alkenylcyclooctyl)-N-aryl(benzyl) amines

The homoallylic amines (6-10) derived from N-cyclooctylidenearyl (benzyl)amines and allyl- or prenylmagnesium bromides as organometallic reagents have been used for synthesis of spiro-N-heterocycles. The tetrahydrospiro[3H-2-benzazepine-3,1'-cyclooctanes] (11 and 12) have been obtained from the homoallylamines (6 and 7) under acidic conditions. The tetrahydro-1-benzazepine (15) spiroannulated with a cyclooctane moiety has been prepared by treating the homoallylic amine (9) with cone, sulfuric acid. Treatment of the homoallylmine (6) with 92% sulfuric acid in chloroform at reflux afforded tetrahydrospiro[1,2,3-oxathiazine-2,2-dioxide-4, 1'-cyclooctane] (17). The latter has been converted into 1-benzyl-4-methylspiro[azetidine-2,1'-cyclooctane] (18). The homoallylamine (6) has been cyclized into the 1-benzylspiro[pyrrolidine-2,1'-cyclooctane] (19).