| 摘要 |
PURPOSE:To obtain in high selectivity the title compound in one step from readily available raw materials by reaction under specified conditions between an aldehyde, aromatic compound and its condensed ring. CONSTITUTION:A reaction is made in a liquid phase in the presence of an acid catalyst (e.g. p-toluenesulfonic acid) between (A) an aldehyde of formula I (R<1> is 2-8C alkyl; R<2> is 1-6C alkyl), (B) an aromatic compound of formula II (R<3> is H, alkyl substituted at aromatic ring or condensed ring; n is 1-3) and (C) a condensed ring compound therefrom to obtain the objective 2,3- dihydrobenzofran (coumaran) of formula III. The molar ratio A/B=(0.1:1)-(10:1) [pref. (1:1)-(3:1)] and the amount of the catalyst to be used is such as to be 0.01-10wt.% based on the component A. |
