Regioselective desymmetrization of diaryltetrahydrofurans via directed ortho-lithiation: An unexpected help from green chemistry
An efficient functionalization of diaryltetrahydrofurans via a regioselective THF-directed ortho-lithiation is first described. This reaction can be successfully carried out in cyclopentyl methyl ether as a greener alternative to Et2O, with better results in terms of yield and selectivity and, surprisingly, also in protic eutectic mixtures competitively with protonolysis.