| 摘要 |
Preparation of 2-(2-formyl-4-nitro-phenoxy or -phenylthio)-alkanoic acid derivatives (I) involves selective introduction of the nitro group using a nitrogen dioxide cation (NO2<+>) source in presence of sulfuric acid. Preparation of nitrobenzaldehyde derivatives of formula (I) involves selective nitration of a benzaldehyde derivative of formula (II) using a nitrogen dioxide cation (NO2<+>) source in presence of sulfuric acid. R1 = H, 1-12C alkyl, phenyl (optionally substituted by 1-4C alkyl) or halophenyl; R2 = H, 1-12C hydrocarbyl, cycloalkyl or phenylalkyl; Z' = O or S; R = H or substituent; 2 adjacent R = may complete a 5-7C saturated, unsaturated or aromatic ring; and n = 0-3. Independent claims are included for: (1) preparation of (II) by reacting a benzaldehyde of formula (II) with a carboxylic acid or derivative of formula Y-CHR1COOR2 (IV); (2) preparation of 5-nitro-benzofurans or -benzothiophenes of formula (V) by cyclization of (I), after saponification if R2 is other than H; and (3) (I) as new compounds, provided that R1 is other than H. Y = leaving group, preferably halo or hydrocarbylsulfonyloxy. |
