hydroxide (Sigma-Aldrich, 40 wt % in water), tetra(n-butyl)phosphonium hydroxide (Sigma-Aldrich, 40 wt % in water), 2-furoic
acid (Sigma-Aldrich, 98%), tetrahydro-2-furoic acid (Sigma-Aldrich,
98%), thiophene-2-carboxylic acid (Sigma-Aldrich, 98%), dichloromethane
(Merck, Analytical grade), diethyl ether (Merk, Analytical grade),
sodium sulfate anhydrous (VWR chemicals, 99.3%), deuterated chloroform
(CDCl3, Sigma-Aldrich, 99.8 at. % D, containing 0.03% (v/v)
tetramethylsilane (TMS)), and ferrocene (Fc, Alfa Aesar, 99.5%) were
used as received.