The 1,3-dipolar cycloaddition reactivity and regioselectivity of methyleneadamantane
1, ethyl adamantylideneacetate
7a, adamantylideneacetonitrile
7b and ω-methoxymethyleneadamantane
7c with substituted benzonitrile oxides
3a-i were calculated by CNDO/2 method using the perturbation equation derived by Klopman and Salem. The calculation predicted an exclusive formation of adamantan - 2 - spiro - 5' - 3' - aryl - Δ
2' - isooxazoline
4a-i in the reactions of
1,
7a and
7b with
3a-i, and a formation of 67–69:33-31 mixture of
4a-i and isomeric
5a-i in the reaction of
7c with
3a-i. The predicted exclusive formation of
4a-i were experimentally observed in the reactions of
1,
7a and
7b with
3a-i generated from
2a-i with Et
3N or thermally, but the reaction of
7c with
3a did not afford the corresponding adducts. A considerably higher reactivity of CN triple bond than CC double bond was observed in the reaction of
7b with
3a and 1,2,4-oxadiazole derivative
11 was obtained as the major product.
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