Asymmetric synthesis of α‐aminophosphonic acids, I enantioselective synthesis of L‐(1‐aminoethyl)phosphonic acid by asymmetric catalytic hydrogenation of N‐[1‐(dimethoxyphosphoryl)ethenyl]formamide

The synthesis of N‐[bis(dimethoxyphosphoryl)methyl]formamide (7) from aminomethylene‐bis(phosphonic acid) (6) is described. 7 reacts with aldehydes in a Wittig‐Horner reaction to give N‐[1‐(dimethoxyphosphoryl)‐1‐alkenyl]formamides 3. From the parent compound 3a L‐(1‐amino‐ethyl)phosphonic acid (1) is obtained with e.e. ca. 76% via asymmetric catalytic hydrogenation using a rhodium catalyst in the presence of (+)‐DIOP.