反应详情

The amide acid VIIC is cyclized by treatment with a cyclizing agent such as acetic anhydride or propionic anhydride (employing a molar ratio of anhydride:VIIC of within the range of from about 7:1 to about 5:1) and amine base such as triethylamine or diisopropylethylamine, in the presence of an inert organic solvent such as THF, toluene, monoglyme or ethylacetate, at a temperature within the range of from about 70° to about 110° C., to form compound XXVIII.