| 摘要 |
PURPOSE:To obtain a new compound useful as a synthetic intermediate for herbicides. CONSTITUTION:The objective compound of formula I (R<1> and R<2> are H, alkyl, halogen, alkoxy, acyl, alkenyl or phenyl or R<1> and R<2>, together with N, are bound to form a heterocyclic ring, etc.; R<3> is H, lower alkyl or benzyl; R<4> is H or protecting group of OH; R<5> is lower alkyl, benzyl or acyl), e.g. methyl 6-(N-benzyl-N-methylamino)-3-benzyloxypicolinate. This compound of formula I is obtained by reacting a picolinic acid N-oxide derivative of formula II with a carbamoyl chloride of formula III (L is releasable group) in an inert solvent (e.g. acetonitrile) at 0 deg.C to the boiling point temperature of the solvent. Thereby, the formation of by-products can be suppressed to synthesize the objective compound of formula I in high purity and yield. |
