Simple assembly of polysubstituted pyrazoles and isoxazoles via ring closure–ring opening domino reaction of 3-acyl-4,5-dihydrofurans with hydrazines and hydroxylamine
作者:Alexey O. Chagarovskiy、Ekaterina M. Budynina、Olga A. Ivanova、Victor B. Rybakov、Igor V. Trushkov、Mikhail Ya. Melnikov
DOI:10.1039/c5ob02596f
日期:——
A convenient general approach to 2-(pyrazol-4-yl)- and 2-(isoxazol-4-yl)ethanols based on the Brønsted acid-initiated reaction of 3-acyl-4,5-dihydrofurans with hydrazines or hydroxylamine was developed. Further transformation of the alcohol moiety in 2-(pyrazolyl)ethanols affording 2-(pyrazolyl)ethylamine as potent bioactive compounds as well as pyrazole-substituted derivatives of antitumor alkaloid
Various 1,3-dicarbonyl compounds reacted readily with benzylic and propargylic alcohols in the presence of 10 mol % of phosphomolybdic acid supported on silica gel (PMA/SiO2) under mild reaction conditions to produce 2-benzylic- and 2-propargylic-1,3-dicarbonyl compounds in excellent yields and with high selectivity.