Monsanto Company

Gerald L Bachman

Billy D Vineyard

Helmut L Merten

Marvin L Oftedahl

Catalytic asymmetric hydrogenation of the Z geometric isomer of a compound of the formula ##STR1## wherein at least one of R and R.sup.1 represents hydrogen and the other represents hydrogen, lower alkyl or aryl; R.sup.2 represents ##STR2## wherein R.sup.4 and R.sup.5 each independently represent hydrogen, lower alkyl or aryl, R.sup.6 represents hydrogen, lower alkyl, aryl or an alkali metal; and R.sup.3 represents ##STR3## wherein R.sup.7 and R.sup.8 each independently represent lower alkyl or aryl; provided that, when R.sup.3 is ##STR4## R.sup.2 is --CN, in the presence of a homogeneous, coordination complex catalyst comprising rhodium, iridium or ruthenium in combination with an optically active bis phosphine ligand provides an outstanding level of optical purity.

Asymmetric catalysis

There is described an improved process for the separation and recovery of L-phenylalanine and L-aspartic acid from sidestreams resulting from the preparation of .alpha.-L-aspartyl-L-phenylalanine methyl ester. It has been found that superior separation is obtained by combining one or more of the mother liquor and wash solutions formed during the preparation of .alpha.-L-aspartyl-L-phenylalanine methyl ester, hydrolyzing same to afford the hydrohalide salts of L-aspartic acid and L-phenylalanine, acidifying the hydrolysis solution to precipitate the hydrohalide salt of L-phenylalanine, separating the hydrohalide salt of L-phenylalanine, dissolving it in water and adjusting the pH of the solution to the isoelectric point of L-phenylalanine, thus affording pure L-phenylalanine, and thereafter adjusting the pH of the solution after separation of the L-phenylalanine hydrohalide to the isoelectric point of L-aspartic acid to precipitate L-aspartic acid.

Recovery of L-phenylalanine and L-aspartic acid during preparation of

Stabilized amorphous calcium carbonate which is useful as a carbonate factor in effervescent compositions. Process for preparing stabilized amorphous calcium carbonate and compositions containing stabilized amorphous calcium carbonate.

Stabilized amorphous calcium carbonate

Catalytic asymmetric hydrogenation of a compound of the formula ##STR1## wherein R, R.sup.1 and R.sup.2 each independently represent hydrogen, substituted or unsubstituted alkyl having from 1 to 5 carbon atoms or substituted or unsubstituted aryl, and R.sup.3 represents substituted or unsubstituted alkyl having from 1 to 5 carbon atoms or substituted or unsubstituted aryl, provided that, if only one of R and R.sup.1 is hydrogen the Z geometric isomer is hydrogenated, in the presence of a homogeneous, coordination complex catalyst comprising rhodium, iridium or ruthenium in combination with an optically active bis phosphine ligand provides an excellent level of optical purity.

A process for the preparation of .alpha.-L-aspartyl-L-phenylalanine methyl ester wherein .alpha.-L-aspartyl-L-phenylalanine is contacted with a reaction medium comprising water, methanol and a hydrogen halide to form a solid hydrogen halide salt of .alpha.-L-aspartyl-L-phenylalanine methyl ester which can be separated and converted to .alpha.-L-aspartyl-L-phenylalanine methyl ester.

Process for the preparation of .alpha.-L-aspartyl-L-phenylalanine methyl

A process which comprises contacting alkyl esters of .alpha.-L-aspartyl-L-phenylalanine with an aqueous solution containing barium ions, at a reaction pH greater than 7, to form .alpha.-L-aspartyl-L-phenylalanine.

Hydrolysis of esters of .alpha.-L-aspartyl-L-phenylalanine

A process for the preparation of .alpha.-L-aspartyl-L-phenylalanine alkyl esters wherein L-phenylalanine is reacted with N-protected-L-aspartic anhydride, the resulting product is treated to yield .alpha.-L-aspartyl-L-phenylalanine which is esterified with an alkanol to yield an .alpha.-L-aspartyl-L-phenylalanine alkyl ester which is recovered. Novel precursors for .alpha.-L-aspartyl-L-phenylalanine alkyl esters are prepared in the process of this invention.

Growing community of inventors

St. Louis, MO, United States of America

Gerald L Bachman