Access to Fully Substituted Dihydroindazoles Via Hexadehydro-Diels-Alder/[3 + 2] Cycloaddition.

A cascade hexadehydro-Diels-Alder (HDDA)/[3 + 2] cycloaddition reaction between tetrayne and N , N '-cyclic acylhydrazone is described. This strategy allows the efficient construction of fully substituted 2,3-dihydro-1 H -indazole scaffolds which have insecticidal activity against the third instar larvae of Mythimna separata .