| 摘要 |
<p>PURPOSE:To obtain the subject compound useful as an acylating agent or a raw material for antibiotic substances by directly providing a 2-hydroxyimino derivative from a 2-(5-protected amino-1,2,4-thiadiazol-3-yl) acetic acid derivative without passing through a 2-oxo derivative and alkylating the resultant derivative while holding the steric configuration. CONSTITUTION:The syn-isomer [e.g. methyl 2-(5-methoxycarbonylamino-1,2,4- thiadiazol-3-yl)acetate] of a compound expressed by formula I (R<1> us carboxy- protecting group; R<2> is amino-protecting group) is reacted with a compound expressed by the formula R<3>X [R<3> is (substituted) alkyl; X is halogen] in the presence of silver acetate or with a compound expressed by the formula R''-Y (Y is acid residue) in the presence of BaO and Ba(OH)2 to provide the syn- isomer of a compound expressed by formula II. The protecting groups, as desired, are released to afford the objective syn-isomer [e.g. methyl (Z)-2-(5- methoxycarbonylamino-1,2,4-thiadiazol-3-yl)-2-methoxyiminoacetate] of the subject compound expressed by formula III (R<1a> is H or carboxy-protecting group; R<2a> is H or amino-protecting group). The compound expressed by formula I is obtained by reacting a compound expressed by formula IV with a nitrous acid ester.</p> |
