title: Preparation of 3,5-disubstituted pyrazoles and isoxazoles from terminal alkynes, aldehydes, hydrazines, and hydroxylamine.
abstract: 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.
authors: Graduate School of Science, Chiba University , Yayoi-cho 1-33, Inage-ku, Chiba 263-8522, Japan.
authors: Ryo
authors: R
authors: Harigae
authors: Katsuhiko
authors: K
authors: Moriyama
authors: Hideo
authors: H
authors: Togo
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D000480:Alkynes / Q000737:chemistry*; D006835:Hydrazones / Q000737:chemistry*; D006898:Hydroxylamines / Q000737:chemistry*; D007455:Iodine / Q000737:chemistry; D007555:Isoxazoles / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D011720:Pyrazoles / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000447:Aldehydes; D000480:Alkynes; D006835:Hydrazones; D006898:Hydroxylamines; D007555:Isoxazoles; D011720:Pyrazoles; D007455:Iodine