Cycloaddition of benzonitrileoxide to pyridazine affords an isolable mono-cycloadduct. In cycloadditions to pyrimidine and pyrazine the primary mono-cycloadducts are labile intermediates which undergo further cycloaddition affording isolable bis- and tris-cycloadducts.
Cycloadditions between nitrile oxides and cis-4-benzoylamino-2-cyclopenten-1-ol offer an example in which a strong intramolecular hydrogen bond completely offsets the syn-directing ability of the cyclopentene substituents. Solvents affected the conformational equilibrium of the cyclopentene dipolarophile but did not sizeably influence the cycloaddition selectivity, showing the absence of directing
2-Aryl-4,6-dibromobenzoxazoles were isolated in the reaction of benzonitrile oxides with S,S-dimethyl-N-(2,4,6-tribromophenyl)sulfimide. Structure determination was done by means of spectroscopic and elemental analyses.
Anionic Domino C<i>-</i>O-Heterocyclization Approach for the Synthesis of 5-Vinyl Isoxazolines
作者:H. Kumar、Naveed Qazi、Parvinder Singh、Sumira Jan
DOI:10.1055/s-2007-980346
日期:2007.6
5-Vinyl isoxazolines were isolated in high yields through domino nucleophilic addition-anionic C-O-heterocyclization, when allyl organometallics derived from trans-1,4-dihalobutene were reacted with nitrile oxides.
2-[3-aryl-2-isoxazolin-5-yl]benzoates and their use as intermediates for agricultural chemicals. The subject isoxazolines can be converted to the corresponding isoxazoles. The latter are useful as herbicides and as plant growth regulants.