| 摘要 |
PURPOSE:To readily obtain the title substance useful as a synthetic intermediate for beta-lactam based antibiotic in mild conditions and good yield by reacting a alpha-substituted carboxylic acid ester derivative with a Schiff base in the presence of tin triflate and base. CONSTITUTION:A compound expressed by formula I (R<1> is protecting group, e.g., lower alkyl or alkylcarbonyl, of the group -XH; R<2> is H, lower alkyl, cycloalkyl, aryl, etc.; R<3> is protecting group of carboxy group; X is O, S, selenium, sulfoxide, etc.) is reacted with a compound expressed by formula II (R<4> and R<5> are H or group comparable with R<2> provided that these are not simultaneously H; Z is protecting group of amino group) in the presence of tin triflate expressed by formula III and base (e.g., triethylamine) to provide the compound expressed by formula IV. Thereby synthesis under mild conditions is made possible and restriction to the Schiff base capable of using for the reaction is remarkably relaxed. |
