Ketoethers, cyclic

Diketones are reductively cyclized in a TFA-catalyzed reaction. The cycliza-tion of the cage structure shown in Eq. 236 illustrates this ring closure in the formation of an acetal of trifluoroacetaldehyde.409 The organosilane reduction of triketone 69 followed by Jones oxidation gives the cyclic ketoether in fair yield (Eq. 237).410... 

Cyclic 3-hydroxy-2-ketoethers from allenealcohols Dioxaspiropentanes as intermediates... 

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