Synthesis of medium and large cyclic amines in rhodium- catalysed reactions of aminoalkenes with H-2/CO

Rhodium-catalysed reactions of N-benzyl- or N-alkyl-aminoalkenes (6) with H -2/CO can give cyclic amines (7) (7-13 ring size) in good to excellent yiel ds when BIPHEPHOS is used as a ligand. Hydrogenation of the aminoalkene bec omes a competing reaction for the smaller rings but can be overcome by usin g a H-2/CO gas ratio of 1 : 5. Reactions of 2-alkenyloxybenzylamines (13) g ave 9-, 12- and 17-membered rings (14) in 30-40% yield, but dimer formation (16) and/or hydrogenation were competing reactions. Similar reactions of a lkenylamides and ortho-alkenylanilines gave only non-cyclized amino aldehyd es as products in low isolated yields.