Synthetic Studies in the Chloramphenicol Series. IV* Synthesis of threo-DL-Chloramphenicol Base from DL-Serine Methyl Ether

A synthesis of threo-DL-chloramphenicol base from a-bromo-B methoxy-propionic acid, an intermediate in the synthesis of DL-serine methyl ether is described. The synthesis is essentially the same as the one previously described for the preparation of threo-DL-chloramphenicol from DL-serine ethyl ether. However, the over-all yield of chloramphenicol base is much higher (6.9%, based on a-bromo-B-methoxy-propionic acid) mainly due to the high yield of a-phthalimido-B-methoxy-propiophenone, which was obtained in a yield of 63.5 %

Synthetic Studies in the Chloramphenicol Series. IV* Synthesis of threo-DL-Chloramphenicol Base from DL-Serine Methyl Ether

A synthesis of threo-DL-chloramphenicol base from a-bromo-B methoxy-propionic acid, an intermediate in the synthesis of DL-serine methyl ether is described. The synthesis is essentially the same as the one previously described for the preparation of threo-DL-chloramphenicol from DL-serine ethyl ether. However, the over-all yield of chloramphenicol base is much higher (6.9%, based on a-bromo-B-methoxy-propionic acid) mainly due to the high yield of a-phthalimido-B-methoxy-propiophenone, which was obtained in a yield of 63.5 %

Introduction of the N-Phthaloyl Group into Heat-Sensitive Amino Acid Derivatives; N-Phthaloyl-L-Aspartic Acid*

A method is described by which heat-sensitive amino acid derivatives can be converted to unracemized N-phthaloyl amino acids using o-carbethoxythiobenzoic acid (II) or its sodium salt. In this manner N-phthaloyl-L-aspartic acid was prepared

Absolute Configuration of β-Hydroxy-β-phenylpropionic acid*

(+)-Methyl β-methoxy-β-phenylpropionate (VIII) was prepared from (+)-mandelic acid and from (+)-β-hydroxy-β-phenylpropionic acid (I). In this way the configuration of I was correlated with that of mandelic acid

Introduction of the N-Phthaloyl Group into Heat-Sensitive Amino Acid Derivatives; N-Phthaloyl-L-Aspartic Acid*

A method is described by which heat-sensitive amino acid derivatives can be converted to unracemized N-phthaloyl amino acids using o-carbethoxythiobenzoic acid (II) or its sodium salt. In this manner N-phthaloyl-L-aspartic acid was prepared

Absolute Configuration of β-Hydroxy-β-phenylpropionic acid*

(+)-Methyl β-methoxy-β-phenylpropionate (VIII) was prepared from (+)-mandelic acid and from (+)-β-hydroxy-β-phenylpropionic acid (I). In this way the configuration of I was correlated with that of mandelic acid

Thiosemicarbazones and 2-Thio-4-(phthalimidoalkylidene) thiazolid-5-ones of N-Phthaloyl Amino Aldehydes. Preparation and Antibacterial Activity

Thiosemicarbazones of the formula I and 2-thio-4-(phthalimidoalkylidene) thiazolid-5-ones of the formula II derived from glycine, L-alanine; B-alanine, DL-leucine, DL-valine, L-tyrosine, DL-serine and a-amino-n-butyric acid were prepared and tested against Staphylococcus aureus, B. pyocyaneus, E. coli and Enterococcus

Synthetic Studies in the Chloramphenicol Series. III. Synthesis of threo-DL-Chloramphenicol from DL-Serine Ethyl Ether

A synthesis of threo-DL-chloramphenicol (I) from a-phthalimido-~-ethoxy-DL-propiophenone (II) is described. The crude ketone II obtained from a-phthalimido-~-ethoxy-DL-propionyl chloride via Friedel-Crafts reaction was reduced with aluminium isopropoxide to give a yield of 17.2 % of the corresponding carbinol III. This carbinol gave in a series of reactions threo -DL-chloramphenicol in an overall yield of 2.4 %

Optically Active Trisulphides and Tetrasulphides Related to L-Cystine

A . description is ,given of the preparation and properties of optically active bis(2-carboxy - 2- phthalimidoethyl) disulphide (Ia), [a]D-275°, bis(2-carboxy -2.:phthalimidoethyl) trisulphide (lb) , ,[a]D -4720 and bis(2-c arboxy -2-phthalimidoethyl) tetrasulphide (le), [a]D:--3880. The starting material for these compounds was N - -phthaloyl-L-cysteine (II), [a]D-64° prepared from L-cysteine hydrocl).loride and sodium o- carbethoxythiobenzoa te

Thiosemicarbazones and 2-Thio-4-(phthalimidoalkylidene) thiazolid-5-ones of N-Phthaloyl Amino Aldehydes. Preparation and Antibacterial Activity

Thiosemicarbazones of the formula I and 2-thio-4-(phthalimidoalkylidene) thiazolid-5-ones of the formula II derived from glycine, L-alanine; B-alanine, DL-leucine, DL-valine, L-tyrosine, DL-serine and a-amino-n-butyric acid were prepared and tested against Staphylococcus aureus, B. pyocyaneus, E. coli and Enterococcus