Cycloocta 4-hydroxy

Cyclooctatetraene reacts as a dienophile with 3,6-bis(trifluoromethyl)-l,2,4,5-tetrazine to form, upon loss of N2, a cycloocta[4]pyridazine and a tetracyclic bis-Diels-Alder cycloadduct [95LA661]. In a nonpolar solvent, the former produced a dihydrobarrelenofrflpyridazine that could be oxidized (with 4-phenyltriazolinedione) to the barreleno[d]pyridazine, but in a polar solvent it gave a dihydrocycloocta[d]pyridazine in a multistep process. X-ray crystal structures of some of these compounds have been obtained. The attempted dehydrogenation of 4,4a-dihydro-5//[ 1 ]benzopyrano[4,3-c]pyridazin-3(2//)-ones with m-CgH NC SOjNa unexpectedly led to new 5-hydroxy[ 1 ]benzopyrano[4,3-c]pyridazin-3(2//)-ones [95JHC79]. 

Oxabicyclo[3.3.I]noHene-l (3).13 This bridgehead alkene was synthesized in the following way. Hydroboration-oxidation of 1,5-cyclooctadiene gave n s-l,5-cycloocta-nediol, which was oxidized by Jones reagents to l-hydroxy-9-oxabicyclo[3.3.1]-nonane (1) in 49% overall yield. Attempts to prepare derivatives of (1) usually led to derivatives of the hydroxy ketone (4) however, reaction of (1) with methanesulfonyl chloride and... 

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