Alkoxy Exchange\nStrategy for the Synthesis of <i>N</i>,<i>N′</i>-Dimethylated (Alkoxy)triazinediones\nas Solid Reagents for Acid-Catalyzed <i>O</i>‑Alkylation

<i>N</i>,<i>N′</i>-Dimethylated\n(alkoxy)triazinediones\n(DMATs-R) with eight different <i>O</i>-alkyl groups (R),\nsuch as benzyl, allyl, and <i>tert</i>-butyl groups, were\nsynthesized in 61–94% yield through the alkoxy exchange reaction\nof DMAT-Me with the corresponding alcohol. Molecular sieves were added\nto the reaction mixture to shift the alkoxy exchange equilibrium toward\nthe product via the absorptive removal of the methanol formed <i>in situ</i>. All the DMATs-R were obtained as stable solids,\nin contrast to previously reported <i>N</i>,<i>N′</i>-diallyl analogs that included oil compounds. The treatment of alcohols\nwith DMATs-R in the presence of an acid catalyst afforded the corresponding\nalkyl ethers in up to 92% yield. A base-labile bromoalkyl group is\ncompatible with these reactions. The <i>O</i>-<i>tert</i>-butylation of a sterically hindered <i>tert</i>-alcohol\nwith DMAT-<sup><i>t</i></sup>Bu yielded the di-<i>tert</i>-butyl ether product. The DMATs-R are suitable reagents for the <i>O</i>-alkylative protection of alcohols under nonbasic conditions.