Studies on the Stability of .DELTA.2 and .DELTA.3 Cephem Esters. I. Marked Difference in Stability between .DELTA.2 and .DELTA.3 Cephem Prodrug Esters and Application to the Preparation of Key Intermediates for Oral Cephem Synthesis.
作者:Shigeto NEGI、Mototuske YAMANAKA、Yuki KOMATSU、Akihiko TSURUOKA、Itaru TSUKADA、Norio MINAMI
DOI:10.1248/cpb.43.1998
日期:——
The esterification of Δ3-cephem-4-carboxylic acid sodium salt (1) with 1-iodoethyl isopropyl carbonate always afforded the Δ2 cephem ester (3) as an inseparable minor component. However, in the course of formamido cleavage reaction, the 7-amino-Δ2-cephem ester (5) was observed to be less stable than the Δ3 cephem ester (4), which led us to develop a practical synthetic process for Δ3 cephem esters, including a key intermediate of E1101, a new oral cephalosporin.
1-iodoethyl isopropyl carbonate酯化Δ3-cephem-4-羧酸钠盐(1)时,总能得到作为不可分割的次要成分的Δ2 cephem酯(3)。然而,在甲酰氨基裂解反应过程中,观察到 7-氨基-Δ2-头孢酯(5)不如Δ3-头孢酯(4)稳定,这促使我们开发出一种实用的Δ3-头孢酯合成工艺,包括一种新型口服头孢菌素 E1101 的关键中间体。