Hydrogenolysis Hydroxyl radical

Surprisingly, additions of electrophiles, radicals, and nucleophiles to methylene cyclopropane have rarely been executed under synthetic conditions. A sequence leading to the complement inhibitor K-76 published recently" very smartly takes advantage of a methylenecyclopropane participation in the polyene cyclization shown in equation 197. Hydroxylation of the vinylcyclopropane double bond and hydrogenolysis of the three membered ring are subsequent essential reactions. 

Formation of hydroxyl quinoline must have been initiated by ionic reactions that involved and OH ions. Hydrogenation by Ha enables the heterocyclic ring to be saturated, and this can be followed by hydrogenolysis of C-N bonds that first open the hetero-ring and then convert the resultant aliphatic and aromatic amine intermediates to hydrocarbons and ammonia (24). Also direct attack of OH on quinoline may have led to formation of hydroxyl quinoline. It has been suggested that both ionic reaction and free radical capping are possible under supercritical conditions (25). 

Methanolysis, then hydrogenolysis with Raney nickel or radical reduction with BusSnH aflForded the 2,6-dideoxy-a-(119) and P-(120)-D-n6o-hexopyranosides. Moreover, 2,6-anhydro-2-thiomannopyranosyl donors 121 (Scheme 28) having an equatorial 3-C>-substituent can be obtained by oxidation of the 3-hydroxyl group... 

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