Synthesis of cis-2-alkoxycyclopropylamines via intramolecular cyclization of 2-azaallylic anions derived from alkoxybrominated N-(arylidene)-2-methyl-2-propenylamines

N-(Arylidene)-2-alkoxy-3-bromo-2-methylpropylamines, obtained in a straightforward way via regiospecific alkoxybromination of the corresponding N-(2-methyl-2-propenyl)imines, represent promising densely functionalized synthetic building blocks. The substituted N-(3-bromopropyl)imines were deprotonated to the corresponding 2-azaallylic anions, which underwent a highly diastereoselective intramolecular ring closure to new cis-N-(arylidene)-2-alkoxy-2-methylcyclopropylamines (cis:trans up to 99:1) in good to excellent yields (62–95%). These cis-cyclopropylamines proved to be excellent precursors of new conformationally constrained β-amino ethers.