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Issue 54, 2016, Issue in Progress
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Isomerizable (E/Z)-alkynyl-O-methyl oximes employing TMSCl–NCS in chlorinative cyclization for the direct synthesis of 4-chloroisoxazoles

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Abstract

For the first time, 4-chloroisoxazoles are directly synthesized in moderate to excellent yields from (E/Z)-alkynyl-O-methyl oximes via chlorinative cyclization. The synthesis employs the combination of N-chlorosuccinimide (NCS) and chlorotrimethylsilane (TMSCl) in nitromethane solvent where chlorine (Cl2) and hydrochloric acid (HCl) are generated in situ. In addition, the current protocol is applicable to the synthesis of 4-bromo- and 4-iodoisoxazoles when N-bromosuccinimide (NBS) and N-iodosuccinimide (NIS), respectively, are employed in place of NCS. The current method can improve the overall efficiency of the preparation of 4-haloisoxazoles starting from the step where alkynyl-O-methyl oximes are prepared since (E)-isomers can isomerize and cyclize under the conditions.

Graphical abstract: Isomerizable (E/Z)-alkynyl-O-methyl oximes employing TMSCl–NCS in chlorinative cyclization for the direct synthesis of 4-chloroisoxazoles

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Publication details

The article was received on 12 Apr 2016, accepted on 08 May 2016 and first published on 09 May 2016


Article type: Paper
DOI: 10.1039/C6RA09396E
Citation: RSC Adv., 2016,6, 48666-48675

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    Isomerizable (E/Z)-alkynyl-O-methyl oximes employing TMSCl–NCS in chlorinative cyclization for the direct synthesis of 4-chloroisoxazoles

    W. Kaewsri, C. Thongsornkleeb, J. Tummatorn and S. Ruchirawat, RSC Adv., 2016, 6, 48666
    DOI: 10.1039/C6RA09396E

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