A green protocol ball milling synthesis of dihydropyrano [2,3
General procedure for the synthesis of PPz. In a stainless steel ball mill vessel, a mixture of ethylacetoacetate (1 mmol), hydrazine hydrate ( mmol), aldehydes (1 mmol), malononitrile (1 mmol), and NanoSiO 2 /AEP ( g) was milled at 20 Hz. The reaction progress was monitored by TLC (nhexane: ethyl acetate [8:2]).