Preparation of 2 H ‐Benzoxetes by Photoinduced [2 + 2] Cycloaddition of Quinone Methides, Accessible by Dimethyldioxirane (DMD) Oxidation of 2,3‐Dimethylbenzofurans
1994; Wiley; Volume: 127; Issue: 6 Linguagem: Inglês
10.1002/cber.19941270622
ISSN0009-2940
AutoresWaldemar Adam, Markus Sauter, Corinna Zünkler,
Tópico(s)Photochromic and Fluorescence Chemistry
ResumoAbstract Irradiation (λ > 366 nm) of the quinone methides 3 , which were formed by valence isomerization of the methyl‐, chloro‐, and tert ‐butyl‐substituted 2,3‐dimethylbenzofuran epoxides 2 , afforded the novel 2 H ‐benzoxetes 4 by photochemical [2 + 2] cycloaddition. These strained and highly labile benzoxetes 4 were spectrally ( 1 H and 13 C NMR) characterized at subambient temperatures. On prolonged storage (2–3 d) at –20 to –10°C, the benzoxetes 4 reverted to the quinone methides 3 and/or benzofuran epoxides 2 .
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