An efficient synthesis of 2, 2-dimethylchromenes was developed to pursue chemical structure-biological activity studies of insect antijuvenile hormones. The combination of Michael condensation and cyclodehydration with polyphosphoric acid gave nearly quantitative yields of alkoxy 2, 2-dimethylchromanones which were reduced and dehydrated in one flask, to yield the respective 2, 2-dimethylchromenes. By these methods several AJH analogs were prepared which possessed greater biological activity than the natural precocenes.