The Particular Sensitivity of Silyl Ethers of d-Glucal toward Two Vilsmeier−Haack Reagents POCl₃·DMF and (CF₃SO₂)₂Ο·DMF. Their Unique and Selective Conversion to the Corresponding C(6)-O-Formates

The two electrophilic Vilsmeier−Haack reagents POCl₃·DMF 2 or (CF₃SO₂)₂Ο·DMF 3 mediate the one-step and selective conversion of O-triethylsilyl (O-TES), O-tert-butyldimethylsilyl (O-TBDMS), O-tert-butyldiphenylsilyl (O-TBDPS), and O-triisopropylsilyl (O-TIPS) ethers of d-glucal to the corresponding C(6)-O-formates.