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Photochemical cycloaddition of o-quinones to allenes; 2-alkylidene-2,3-dihydro-1,4-dioxins

✍ Scribed by H. J. T. Bos; C. Slagt; J. S. M. Boleij

Publisher
Elsevier Science
Year
2010
Tongue
English
Weight
393 KB
Volume
89
Category
Article
ISSN
0165-0513

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✦ Synopsis

Abstract

Phenanthroquinone was added photochemically to allene and nine of its methyl, methoxy and methylthio derivatives. Several 2‐alkylidene‐2,3‐dihydrophenanthro[9,10‐b]‐1,4‐dioxins were isolated; 2: 1‐adducts were sometimes found as byproducts. The directiospecificity of the addition was investigated. The stereochemistry and conformation of the adducts are discussed in relation to long‐range NMR coupling constants. Tetrachloro‐o‐benzoquinone was added similarly to methoxyallene. This addition could also be performed thermally.

📜 SIMILAR VOLUMES

(2 + 2)-Cycloaddition of o-quinones to N
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In the reactions of nitrone 1 with several methylene-y-butyrolactones 2-5 we have isolated and identified in all the cases the corresponding [3+21 cycloadducts. In all the adducts the oxygen atom of the dipole has linked to the more substituted carbon atom of the exocyclic double bond of the lactone