Palladium-catalysed asymmetric allylation and complex formation involving P,N-bidentate diamidophosphites with 1,3,2-diazaphospholidine cycles

New chiral P,N-bidentate 1,3,2-diazaphospholidine ligands were obtained by one-step phosphorylation of (2S,3S)-2-(ferrocenylideneamino)-3-methylpentan-1-ol and (4S,5S)-(−)-2-methyl-4-hydroxymethyl-5-phenyl-2-oxazoline. Complexation of the new ligands with [Rh(CO)2Cl]2 and [Pd(allyl)Cl]2 was found to give chelate complexes [Rh(CO)Cl(η2-P,N)] and [Pd(allyl)(η2-P,N)]+BF4-, correspondingly. With the new P,N-ligands, up to 70% ee was achieved in the asymmetric Pd-catalysed sulfonylation of 1,3-diphenyl-2-propenyl acetate with sodium p  -toluenesulfinate. In the enantioselective alkylation of 1,3-diphenyl-2-propenyl acetate with dimethyl malonate, up to 91% enantioselectivity was achieved by using [Pd(allyl)(η2-P,N)]+BF4- complexes as chiral catalysts.

Graphical abstractNovel chiral P,N-bidentate 1,3,2-diazaphospholidine ligands and metal chelate complexes [Rh(CO)Cl(η2-P,N)] and [Pd(allyl)(η2-P,N)]+BF4- on their basis were synthesised. Chiral diamidophosphites gave up to 91% ee in the Pd-catalysed allylic substitution of 1,3-diphenylallyl acetate with dimethyl malonate and up to 70% ee in the allylic substitution of 1,3-diphenylallyl acetate with sodium para-toluene sulfinate.Figure optionsDownload full-size imageDownload as PowerPoint slide