Takao Takaya

STUDIES ON β-LACTAM ANTIBIOTICS

The synthesis and some biological properties of 7 beta-[(Z)-2-(2-amino-4-thiazolyl)-2-(carboxymethoxyimino) acetamido]-3-vinyl-3-cephem-4-carboxylic acid (3, FK027) are described. Diphenylmethyl 7-amino-3-vinyl-3-cephem-4-carboxylate hydrochloride (8), the cephem precursor to FK027 was prepared from 7-aminocephalosporanic acid (7-ACA) by two parallel routes differing primarily in the protection of the 7-amino group. Compound 8 was alternatively prepared from deacetylcephalosporin C sodium salt (DCCNa) with improved yields. Two pathways for the conversion of 8 to FK027 are provided. The new orally active cephalosporin, FK027, possesses a widely expanded antimicrobial activity and high stability to beta-lactamases.

Synthesis of protected purpurosamine B and 6-epipurpurosamine B

In relation to the synthesis of antipseudomonal drugs, namely, gentamicin C2 and 3-de-O-methylsporaricin A, a protected purpurosamine B (15) and 6-epipurpurosamine B (13) were synthesized. The key intermediate, methyl 2,3,4,7- tetradeoxy-6-O-(methylsulfonyl)-2-phthalimido-beta-L-lyxo-++ +heptopyranoside (8), was obtained in 48% yield by Grignard addition to methyl 2,3,4-trideoxy-2-phthalimido-alpha-D-erythro-hexodialdo-1,5-pyrano side (7) proceeding in accordance with Crams chelate rule, followed by methylsulfonylation. From 8, compound 15 was readily obtained by introduction of the azide group with inversion of configuration at C-6. Compound 13 was obtained by introduction of the azide group with retention of configuration.