Synthesis of enantiopure C-1 symmetric diphosphines and phosphino-phosphonites with ortho-phenylene backbones

Reaction of 2-(diphenylphosphino)phenylphosphonous acid tetramethyldiamide 1 with (+)-menthol, (1S,2S,3S,5R)-isopinocampheol and (1R,2R)-trans-cyclohe xanediol affords enantiopure phosphino-phosphonite ligands 3-5. The X-ray s tructures of 1 (space group P2(1)/n) and 3 (space group P2(f)) have been de termined. The reaction of 1 with (1R,2R,3S,5R)-(-)-pinanediol proceeds dias tereoselectivity to afford a novel type of enantiopure phosphino-phosphonit e ligand 6 with an asymmetric substituted P atom. On reaction of (+)-cedryl alcohol with 1 the adduct 7 oi. the phosphonous acid 2-Ph2P-C6H4P(-O)(H)OH 9 and its dimethylammonium salt is formed through elimination of water and subsequent hydrolysis. The structure of 7 (space group P (1) over bar) was elucidated by X-ray structural analysis. Reduction of the chlorophosphine 8 with LiAlH4 yields the novel primary-tertiary phosphine 10. which is a va luable starting material for the synthesis of. the enantiopure C-1 symmetri c bidentate phospholane ligands 11 and 12. (C) 2001 Elsevier Science Ltd, A ll rights reserved.