| abstract |
Prodn. of 2-substd. amino-benzoxazole or -benzimidazole cpds. of formula (I), comprises reacting the prim. amino cpd. (II) with amine R1R2NH (III) in presence of acid catalyst. In (I)-(III) Z = NH or O; R1 = H, alkyl or alkenyl, hydroxyalkyl, or opt. substd. benzyl; R2 is as R1 but not H, or R1 and R2 together complete a heterocycle, opt. contg. additional heteroatoms or substituents; Rn = one or more H, alkyl, halo, NO2, alkoxy, alkoxycarbonyl or one CN. More specifically the catalyst is a 1-4C alkyl or opt. alkyl-substd. phenyl-sulphonic acids, particularly p-toluenesulphonic and methanesulphonic acid. Reaction is in inert solvent, esp. toluene, at 100-200, esp. 140-180 deg. C. (III) is 3-30, pref. 4-20, moles equivalent per mole (II) and the catalyst is 5-100 mole %. USE/ADVANTAGE - (I) are intermediates for pharmaceuticals (e.g. muscle relaxants or antihistamines); light-protection agents and herbicides. This method is simple (only one stage) and provides gooo yields of high quality (I) without use of dangerous reagents. |