The reaction of terminal alkynes with n-BuLi, and then with aldehydes, followed by the treatment with molecular iodine, and subsequently hydrazines or hydroxylamine provided the corresponding 3,5-disubstituted pyrazoles or isoxazoles in good yields with high regioselectivity, through the formations of propargyl secondary alkoxides and α-alkynyl ketones. The present reactions are one-pot preparation of 3,5-disubstituted pyrazoles from terminal alkynes, aldehydes, molecular iodine, and hydrazines, and 3,5-disubstituted isoxazoles from terminal alkynes, aldehydes, molecular iodine, and hydroxylamine.

A variety of 5-aryl-2-methyltetrazoles and 5-aryl-2-benzyltetrazoles were directly prepared in good to moderate yields by the reaction of aromatic aldehydes with methylhydrazine and benzylhydrazine, followed by treatment with di-tert-butyl azodicarboxylate and [bis(trifluoroacetoxy)iodo]benzene in a mixture of dichloromethane and 2,2,2-trifluoroethanol at room temperature. The present method is a novel one-pot preparation of 5-aryl-2-methyltetrazoles and 5-aryl-2-benzyltetrazoles through a [2N + 2N] combination under transition metal-free and mild conditions.

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A novel one‐pot, two‐step preparation of 5‐aryltetrazoles from aromatic aldehydes and alkylhydrazines is presented.

Preparation of 3,5-Disubstituted Pyrazoles and Isoxazoles from Terminal Alkynes, Aldehydes, Hydrazines, and Hydroxylamine. -A simple and practical one-pot method for the highly regioselective synthesis of 3,5-disubstituted pyrazoles [e.g. (III), (V), and (VII)], isoxazoles [e.g. (XII), (XIV), and (XV)] from easily available compounds is presented. Noteworthy, for the third step THF must be removed prior tBuOH is added avoiding a decrease of the product yield. -(HARIGAE, R.; MORIYAMA, K.; TOGO*, H.; J.