Based on the promising results obtained with perillyl alcohol, we decided to extrapolate the reaction to the STL compounds of interest (Figure .), using DHLc as our main substrate. The lipase-catalyzed acylation with vinyl acetate as the acyl donor proceeded under similar reaction conditions as before. The reaction was conducted in a small glass 2 mL glass vial, with 1 mL of MTBE:ACN (3:1), 20 mg of the immobilized lipase (Novozym 435), 10 mM of DHLc and 10 equivalents of acyl donor in the presence of 3 particles of molecular sieves 5 Å at 37 °C. Negative controls in the absence of Novozym 435 and without either DHLc or vinyl acetate were also conducted in parallel. The reaction was stopped after 48 h and the resulting mixture was analyzed by 1 H NMR after filtration and concentration (8 mbar, 35 °C, 2 h) as previously described. For the reaction mixture in the presence of the enzyme, the signals of the two hydrogens adjacent to the primary hydroxy group of DHLc (15a and 15b) shifted to higher ppm values. Each of them initially appearing as a doublet of doublets with strong roof effect at 4.23 ppm (J= 18.8 Hz, 4.9 Hz) and 4.65 (J= 18.8 Hz, 5.7 Hz). As a replacement, two new peaks with similar coupling characteristics appeared at 4.83 and 5.22 ppm, respectively (Figure .). This shift is most probably attributable to the deshielding effect caused by the formation of an ester group, which possesses a greater electro-attractive effect than the original alcohol. This was confirmed by the blank reaction in the absence of the enzyme, where no shift appeared. Therefore, we used this couple of protons to monitor and validate the acylation of the primary alcohol group of DHLc for the rest of the study. It should also be noted that no shift was observed for the hydrogen adjacent to the secondary alcohol group, as well as those related to the lactone moiety. This showed two important findings: (1) The reaction catalysed here by Novozym 435 is very selective for the primary alcohol; (2) The enzyme is not able to hydrolyze the lactone, allowing us to obtain the acetyl derivative of DHLc with 100 % ± 5 % yield. Given the cost of the starting substrate, we maximized our chances of obtaining a detectable yield with DHLc by using a larger amount of enzyme in this first trial than in the preliminary study with perillyl alcohol (20 mg here versus 10 mg previously). However, given the very high conversion, we repeated the operation under identical conditions using only 2 mg of enzyme; a conversion of 100 % ± 5 % was again obtained in only 24 h, demonstrating the very good acceptance of DHLc by the lipase. As DHLc proved to be an excellent substrate for the enzyme, we were curious to know whether acetic acid could also be used as an effective acyl donor. Particularly in order to consider its use on a larger scale, as vinyl esters are typically more toxic than the corresponding carboxylic acid, and due to the generation of acetaldehyde. The reaction was thus carried out under the same conditions as before, with 20 mg of lipase. A conversion of 74 % was achieved after 24 h and a maximum of 76 % after 48 h, demonstrating the presence of a thermodynamic equilibrium under our conditions, despite the addition of the molecular sieves. We deemed important to let the reaction run for 6 days to confirm this observation. After 6 days, the yield of DHLc acetate reached 72 % with 28 % of unreacted DHLc, no by-products were observed, as confirmed by LC-MS (Figure .). Interestingly, no esterification was observed on the secondary alcohol, demonstrating the selectivity of the enzymatic reaction irrespective of the nature of the acyl donor.