Propellane lactones

Propellane lactones. 12-Oxo-l l-oxa[4.4.3] propella-3,8-diene (5) has been synthesized by the reaction of isotetralin (1) with a-chloro-N-cyclohexylacetal-donitrone (2). ... 

Propellane lactones, 107 Propenylbenzene, 571 1-Propenyllithium, 495 Propenyltriphenylphosphonium bromide,... 

In the Baeyer-Villiger oxidation of [4.3.3]propellane-8,ll-dione 74 the propellane-bis-lactones formed, 75 and 76, are accompanied by a dispirolactone 77 22. Different product mixtures result when different (acidic or more basic) reaction conditions are employed but it has been shown experimentally for the head-to-tail propellane bis-lactone 75, vis-a-vis the isomeric dispiran 77, the latter appears to be the thermodynamically more stable product, resulting from the former under acidic conditions (p-TsOH/ C6H6, 7 days, r.t.). The structures were established by means of X-ray diffraction and H- and 13C-NMR spectroscopy. 

Addition to six-membered oxygen heterocycles is also common. The photocycloaddition of 5,7-dimethoxycoumarin to tetramethylethylene has been described,269 and 4-hydroxycoumarin (326) undergoes facile addition to cyclohexene on direct irradiation to give the cyclobutane (327)270 analogous additions to a variety of other alkenes have been reported, and the cycloaddition of 4-methoxycoumarin to 2-methylpropene has been employed in a synthesis of l,2-dihydrocyclobuta[c]coumarin.271 Photoaddition of the 1,2-bisenol lactone (328) to tran.s-stilbene yields propellane (329),272 and [ 2 + 2] cycloaddition is observed along with other competing photoreactions on irradiation of chromone in the presence of alkenes.273... 

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