141525-28-2Relevant academic research and scientific papers
Microwave accelerated cycloaddition reactions of nitrile oxides and allylic alcohols
Lu, Ta-Jung,Tzeng, Gwo-Ming
, p. 189 - 196 (2007/10/03)
The application of microwaves in promoting the cycloaddition reactions of allyl alcohols with nitrile oxides using a domestic microwave oven and a focused monomode microwave reactor have demonstrated that not only was the reaction time substantially reduced, but also the reaction yields were significantly improved over the conventional stirred reactions. Microwave irradiation alters the regioselectivity of the cycloaddition reaction which favors the non-hydrogen-bond directed cycloadduct, isoxazoline 4.
First successful metal coordination control in 1,3-dipolar cycloadditions. High-rate acceleration and regio- and stereocontrol of nitrile oxide cycloadditions to the magnesium alkoxides of allylic and homoallylic alcohols
Kanemasa, Shuji,Nishiuchi, Masaki,Kamimura, Akio,Hori, Kenzi
, p. 2324 - 2339 (2007/10/02)
The first successful control of stereo- and regioselectivity in 1,3-dipolar cycloadditions by metal coordination is described. The presence of magnesium ions dramatically accelerates nitrile oxide dipolar cycloadditions to allylic alcohols, improving both the regio- and stereoselectivity of the reaction. For example, cycloadditions to terminal allylic alcohols bearing α-chirality produce syn-stereoisomers of 2-isoxazolines selectively, and reactions involving the magnesium alkoxides of internal allylic alcohols are exclusively regioselective in favor of 5-hydroxymethyl-2-isoxazolines. Metal alkoxides other than magnesium, such as lithium, zinc, and aluminum alkoxides, are less effective. These reactions involve the formation of activated intermediates in which a nitrile oxide and an allylic alkoxide coordinate to the magnesium ion. Theoretical calculations indicate that the formation of the coordinated intermediates enhances the rate of cycloaddition and also improves the syn-selectivity.
Regiocontrol of Nitrile Oxide Cycloadditions to Allyl Alcohols. Synthesis of 4-Substituted and 4,4-Disubstituted 5-Hydroxymethyl-2-isoxazolines
Kanemasa, Shuji,Nishiuchi, Masaki,Wada, Eiji
, p. 1357 - 1360 (2007/10/02)
The first regiocontrol of nitrile oxide cycloadditions is described.Reaction of benzonitrile oxide with (E)-2-butenol is highly accelerated by the presence of a magnesium alkoxide, and this reaction proceeds in an exclusively regioselective manner to produce 5-hydroxymethyl-4-methyl-3-phenyl-2-isoxazoline as the sole cycloadduct.Synthetic applications to other substituted allyl alcohols are discussed.
