- Stereospecific nucleophilic trapping of encounter complexes between photoexcited 1-cyanonaphthalene and norbornadiene
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Photo-induced electron donor-acceptor reactions between 1-cyanonaphthalene (CNN) and norbornadiene (N) generate products of several structure types. Methanol adducts (1-3) formed in polar solvents are rationalized via the radical cation, N+., and stereospecific (exo-) nucleophilic attack by methanol. In less polar solvents, CNN and N form [2 + 2]-cycloadducts, exclusively on the exo-face of N. In non-polar solvents containing methanol, CNN, N and methanol combine to form 1:1:1 adducts, containing the sensitizer on the endo- and the methoxy groups on the exo-face. The formation of these products is rationalized via the trapping of encounter complexes of different geometries. Any rearrangement of the norbornenyl system can be eliminated, since neither tricyclyl nor 7-methoxynorbornenyl structures are formed. Apparently, the alcohol captures an endo-encounter complex of CNN and N by attack from the exo-face, similar to the attack of methanol on N+..
- Weng, Hengxin,Roth, Heinz D.
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p. 101 - 108
(2007/10/03)
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- Carbenes and the O-H Bond: Norbornenylidenes
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Bicyclohept-2-en-7-ylidene 10 and bicyclohept-5-en-2-ylidene 21 are shown to react with methanol by way of proton transfer, with formation of norbornenyl cations.
- Kirmse, Wolfgang,Meinert, Thomas
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p. 1065 - 1066
(2007/10/02)
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