New Reagents for the Synthesis of Arylmethyl Ethers and Esters

Abstract

This Account chronicles efforts leading up to the development of new arylmethyl transfer (benzylation) reagents for protecting oxygen functional groups under relatively mild and neutral conditions. It begins with an investigation of organosiletanes as surrogate hydroxyl groups, which inspired siletane-functionalized benzyl ethers and forced us to confront the difficulties associated with the synthesis of benzyl ethers. The end result is a new series of neutral oxypyridinium salts for the benzylation of various nucleophilic functional groups under mild conditions.

Development of Triazine-Based Benzylating Reagents Possessing <i>t</i>-Butyl Group on the Triazine Core: Thermally Controllable Reagents for the Initiation of Reaction

“…No racemization was observed during the benzylation of 1i. The O-benzylation of cholesterol 1k also afforded the corresponding ether 2k in good yields (entries 15,16). Although tertiary alcohols, such as 1l and 1m, and their ethers (2l and 2m) are known to decompose under acidic or heating conditions, 2l and 2m were obtained without decomposition using approximately stoichiometric amount of X-b (entries [17][18][19][20].…”

“…DPT-BM (X-a) has several advantages compared with other representative benzylating reagents, such as benzyl triflate (BnOTf) 13) and 2-benzyloxy-1-methylpyridinium triflate (Dudley reagent), [14][15][16][17][18] available under neutral conditions. DPT-BM (X-a) is a non-hygroscopic and stable solid, allowing its treatment under atmospheric conditions.…”