Experimental Chemicals and general measurements

Reactions were monitored by gas chromatography (GC) using Biotin-HPDP chromatograph fitted with a semi-volatile capillary column (l = 30 m, Ø = 0.25 mm, df = 0.25 μm) with a 40–250 °C temperature range (10 °C min−1) program. Calibration curves were carried out with different concentrations of reagents, by-products and dodecane (internal standard) for the quantification of substances after the reactions. NMR spectra were recorded in CDCl3 at 400 MHz (1H), 100 MHz (13C). Melting points (mp) were measured on a capillary melting apparatus and are toxins uncorrected. Chemical shifts (δ) are reported in parts per million (ppm) and calibrated according to the residual solvent signal. Coupling constant values (J) are given in hertz (Hz) and refer to apparent multiplicities, indicated as follows: s (singlet), d (doublet), t (triplet), dd (doublet of doublets). Mass spectra (in electronic impact (EI+) ionization mode) were measured on a GC-MS spectrometer.