IBX/LiBr-promoted one-pot oxidative anti-Markownikov bromohydroxylation/bromoalkoxylation of Baylis-Hillman olefins

The first example of one-pot oxidative anti-Markownikov bromohydroxylation and bromoalkoxylation of Baylis-Hillman (BH) adducts (olefins) is reported. The reaction is performed at rt using LiBr as the bromine source and 2-iodoxybenzoic acid (IBX) as the oxidant. The process involves oxidation of BH adducts with IBX to give β-ketomethylene compounds in situ, which undergo highly regioselective vicinal functionalization with LiBr/H2O or LiBr/ROH in the same vessel to afford α-bromo-β-hydroxy or α-bromo-β-alkoxy compounds, respectively, in excellent yields. The α-bromo-β-hydroxy compounds are readily transformed into epoxides in aq NaOH.

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