401.7 g |
With Novozym 435; In n-heptane; at 65℃; under 65 - 85 Torr;Dean-Stark; |
To a 3-neck, 2-L round bottom flask fitted with an overhead stirrer and a Dean-Stark trap with cold-finger condenser was added methyl laurate (302 g, 1 .41 mol) and 3-hydroxymethyl-1 -methylpiperidine (200 g, 1 .56 mol). Novozym 435 (30 g) was added, followed by the addition of heptane (120 mL). The internal pressure was reduced to 85 mm Hg and controlled by a vacuum regulator. The mixture was heated to 65°C. After 1 .5 hrs, 23 ml_ of methanol had collected in the Dean-Stark trap. At that point, the reaction was cooled to ambient temperature. The mixture was allowed to stand overnight. The following morning, the pressure was once again reduced to 85 mm Hg, and the mixture was heated to 65°C. The reaction was checked by 1 H NMR after 5.5 hours. Additional 3-hydroxymethyl-1 -methylpiperidine (9.00 g) was added. After 7.5 hrs, the mixture was cooled to ambient temperature. Then additional 3-hydroxymethyl-4-methylpiperidine (17.9 g) was once again added. The pressure was reduced to 65 mm Hg, and the mixture was heated to 65°C. After 5 hrs, the reaction was stopped. The mixture was filtered, and the solids were washed with additional heptane. Heptane (500 ml_) was added to the organics, which were then washed with water (1 x 500 ml_). After the layers were separated, the organics were dried with Na2SO4. After filtration, most of the volatiles were removed at reduced pressure. The remaining material was heated to 50°C and sparged (subsurface) for ca. 24 hrs with nitrogen at 100 mL/min to drive off residual heptane affording the title compound as a pale yellow oil (401 .7 g) that was 98.4percent pure by 1 H NMR analysis. 1 H NMR (300 MHz, CDCI3) delta 3.95 (m, 2H), 2.08 (m, 2H), 2.30 (t, J = 9 Hz, 2H), 2.27 (s, 3H) 2.01 -1 .83 (m, 2H); 1 .77-1 .56 (m, 8H); 1 .37-1 .21 (m, 17H), 0.89 (t, 3H).HPLC (150 x 4.6 mm Zorbax SB-C8 column, 75:25 (v:v) (0191) methanol :water (containing 0.1 vol percent trifluoroacetic acid) for 10 min, gradient to 100percent methanol over 1 min, held at 100percent methanol for 9 min, ELSD detection): tR (laurate ester) 5.0 min. |