A Simple and Efficient One‐Pot Synthesis of 3‐Acylisoxazolines from Alcohols and α‐Nitro Ketones in the Presence of NaHSO4/SiO2.

A simple and efficient method for the synthesis of 3‐acylisoxazolines has been developed using alcohols and α‐nitro ketones in the presence of NaHSO4/SiO2. The alcohols and α‐nitro ketones are initially converted into alkenes and nitrile oxides, respectively, and then react with one another to give 3‐acylisoxazolines. This procedure, using alcohols, gave the desired dihydroisoxazoles more effectively than the conventional procedure using alkenes as starting materials. The reaction proceeded through three pathways depending on the type of alcohol used; reactions between nitrile oxides and (I) endo and exo alkenes, (II) dimerized alkenes and (III) single alkenes. Most of the reactions proceeded efficiently and gave the corresponding 3‐acylisoxazolines in good to excellent yield. Three types of reactions between nitrile oxides and (I) endo and exo alkenes, (II) dimerized alkenes, and (III) single alkenes, in which all the alkenes were generated in situ by NaHSO4/SiO2 are presented. This procedure allowed the concomitant generation of both nitrile oxides and alkenes in a single reaction vessel, gave higher yields for the expected isoxazoline products than the conventional method using alkenes as the starting materials. [ABSTRACT FROM AUTHOR]