J. Leitich, I. Heise
Jan 28, 2002
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0
Influential Citations
2
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Journal
Journal of Photochemistry and Photobiology A-chemistry
Abstract
Abstract The photoreactions of two 3-alkoxy-1,1,-dicyano-1-alkenes, viz. 2-(2,2-dimethyl-tetrahydrofuran-3-ylidene)-malononitrile (1) and 2-(2-methoxy-2-methyl-propylidene)-malononitrile (6), and of the analogue of 1 bearing methylamino in place of oxygen, 8, on direct irradiation has been investigated. Compounds 1 and 6 rearrange to 2-alkoxy-1,1-dicyano-cyclopropanes via 1,2-migration of methyl followed by ring closure. The cyclopropanes are thermally unstable but when the irradiation of 1 was carried out in methanol, the product 4 resulting from ring opening addition of methanol to the cyclopropane was obtained in high yield. In contrast to 1, 8 was photostable due to efficient intramolecular quenching of the excited dicyanoalkene chromophore by the tertiary amine nitrogen atom. A 1,3-transposition product of 1, 3-isopropylidene-tetrahydrofuran-2,2-dicarbonitrile (3), is formed as a by-product of 4. Its probable mode of formation is discussed.