The title compounds are obtained by racemate resolution of D,L-homoalanin-4-yl(methyl)phosphinic acid via precipitation of one of the diastereomeric salts using chiral bases such as quinine or cinchonine. It is possible to increase the yield of desired enantiomer by transformed racemate resolution when the precipitation of the diastereomeric salt takes place with the racemization of the undesired enantiomer in the presence of (hetero)--aromatic aldehydes. The racemization method is also suitable for structurally different optically active amino acids.
![Processes for preparing [L]- or [D]-homoalanin-4-yl-(methyl) phosphinic acid and salts thereof by racemate resolution - US Patent 5869668 - Page 1](http://www.wikipatents.com/processes-for-preparing-l--or-d-homoalanin-4-yl-methyl-phosphinic-acid-and-salts-thereof-by-racemate-resolution/T/US5869668-1.jpg "Processes for preparing [L]- or [D]-homoalanin-4-yl-(methyl) phosphinic acid and salts thereof by racemate resolution - US Patent 5869668 - Page 1")
![Processes for preparing [L]- or [D]-homoalanin-4-yl-(methyl) phosphinic acid and salts thereof by racemate resolution - US Patent 5869668 - Page 2](http://www.wikipatents.com/processes-for-preparing-l--or-d-homoalanin-4-yl-methyl-phosphinic-acid-and-salts-thereof-by-racemate-resolution/T/US5869668-2.jpg "Processes for preparing [L]- or [D]-homoalanin-4-yl-(methyl) phosphinic acid and salts thereof by racemate resolution - US Patent 5869668 - Page 2")
![Processes for preparing [L]- or [D]-homoalanin-4-yl-(methyl) phosphinic acid and salts thereof by racemate resolution - US Patent 5869668 - Page 3](http://www.wikipatents.com/processes-for-preparing-l--or-d-homoalanin-4-yl-methyl-phosphinic-acid-and-salts-thereof-by-racemate-resolution/T/US5869668-3.jpg "Processes for preparing [L]- or [D]-homoalanin-4-yl-(methyl) phosphinic acid and salts thereof by racemate resolution - US Patent 5869668 - Page 3")
![Processes for preparing [L]- or [D]-homoalanin-4-yl-(methyl) phosphinic acid and salts thereof by racemate resolution - US Patent 5869668 - Page 4](http://www.wikipatents.com/processes-for-preparing-l--or-d-homoalanin-4-yl-methyl-phosphinic-acid-and-salts-thereof-by-racemate-resolution/T/US5869668-4.jpg "Processes for preparing [L]- or [D]-homoalanin-4-yl-(methyl) phosphinic acid and salts thereof by racemate resolution - US Patent 5869668 - Page 4")
![Processes for preparing [L]- or [D]-homoalanin-4-yl-(methyl) phosphinic acid and salts thereof by racemate resolution - US Patent 5869668 - Page 5](http://www.wikipatents.com/processes-for-preparing-l--or-d-homoalanin-4-yl-methyl-phosphinic-acid-and-salts-thereof-by-racemate-resolution/T/US5869668-5.jpg "Processes for preparing [L]- or [D]-homoalanin-4-yl-(methyl) phosphinic acid and salts thereof by racemate resolution - US Patent 5869668 - Page 5")
![Processes for preparing [L]- or [D]-homoalanin-4-yl-(methyl) phosphinic acid and salts thereof by racemate resolution - US Patent 5869668 - Page 6](http://www.wikipatents.com/processes-for-preparing-l--or-d-homoalanin-4-yl-methyl-phosphinic-acid-and-salts-thereof-by-racemate-resolution/T/US5869668-6.jpg "Processes for preparing [L]- or [D]-homoalanin-4-yl-(methyl) phosphinic acid and salts thereof by racemate resolution - US Patent 5869668 - Page 6")
