Asymmetric addition of dimethylzinc to alkylidenmalonates mediated by phosphorous ligands: a new synthetic route to floral fragrances.

Six new phosphite ligands were prepared and their efficiency as chiral ligands was investigated in the copper-catalyzed asymmetric conjugate addition of dimethylzinc to diethyl 3-phenylpropylidenmalonate (5), affording the addition product with ees up to 74%. Moreover, a simple and straightforward route to floral fragrances Phenoxanol, Citralis, and Nitrile Citralis in optically active form through the above cited reaction was proposed.