Synthesis of substituted 1,4-dioxenes through O–H insertion and cyclization using keto-diazo compounds

Abstract

1,4-Dioxenes present interesting potential as synthetic intermediates, and as unusual motifs for incorporation into biologically active compounds. Here, an efficient synthesis of functionalized 1,4-dioxenes is achieved in two steps through a ruthenium catalyzed O–H insertion and base mediated C–O cyclization strategy. From keto-diazo compounds, O–H insertion with bromohydrins, followed by enolization results in cyclization by O–alkylation of the keto-enolate, with excellent selectivity. A variety of substituted bromohydrins and anion-stabilizing functional groups in the diazo-component are tolerated, to afford novel functionalized dioxenes. The use of enantioenriched -bromohydrins provides enantioenriched 1,4-dioxenes