The Photochemistry of Acrylonitrile with Methoxylated Naphthalenes: Introducing the Photochemical Electrophile-Olefin Combination, Aromatic Substitution (Photo-EOCAS) Reaction

Abstract

The photochemical reactions of acrylonitrile (1) with 1,5-dimethoxynaphthalene (2), 1-methoxynaphthalene (3) and 1,4-dimethoxynaphthalene (4) in various solvents have been investigated. In polar solvents (methanol and acetontrile), an electron transfer pathway leads to the formation of aromatic substitution (with 2 and 3) and addition products (with 4). In benzene, an exciplex-mediated [2π + 2π] cycloaddition occurs. The cycloadducts formed undergo a further photoinduced rearrangement via a [2σ + 2σ] cycloreversion followed by an intramolecular [4π + 2π] cycloaddition.

Key words

photochemistry - electron transfer - alkylations - cycloadditions - rearrangements

References and Notes

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7

Half-wave excited state oxidation potential, E ^ox* = E ^ox - E _0,0, where E ^ox is the half-wave oxidation potential of the ground state and E _0,0 is the excited state energy. Values obtained from Ref 3a.

9

Crystallographic data (excluding structure factors) for the structures in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication no. CCDC 162031-162034 (compunds 6, 7, 16 and 12, respectively).Copies of the data can be obtained, free of charge, on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax: [phone] or e-mail: [e-mail])

12

It has been estimated [11] that a PET process will proceed at a diffusion-controlled rate when the free energy is less than -20 kJ mol^-1.

21

Molecular Structure Corporation, teXsan for Windows, Single Crystal Structure Analysis Software, Version 1.06, 1997-1998.

22

Sheldrick, G. M. SHELX-97, Program for Crystal Structure Determinations; 1997.