24.4%; 77.8% |
With dmap; 1,2-dichloro-ethane; In N,N-dimethyl-formamide; at 110.0℃; for 9.5h;Inert atmosphere; |
4CPA (880 mg, 3.38 mmol), EDC (972 mg, 5.07 mmol), DMAP(206 mg, 1.69 mmol) and glucopyranose 18 (400 mg, 1.69 mmol)were stirred for 9.5 h in DMF (5 mL) at 110C under a N2 atmosphere.After confirmation of the reaction by TLC, the solution was azeotropically evaporated with toluene. The residue was diluted with CHCl3 and washed with ice-cold water, satd aqNaHCO3, and brine. The solution was dried over anhyd MgSO4.The suspension was filtered through a celite bed and concentrated.Purification on silica gel with 4:1 (v/v) n-hexane-EtOAc yielded crystalline beta-ester 19 (629 mg, 77.8%) and crystalline alpha-ester(197 mg, 24.4%) as a colorless syrup: Rf 0.55 (alpha-ester), 0.60 (beta-ester)[2:1 (v/v) n-hexane-EtOAc]; [a]D25 13.9 (c 1.00, CHCl3);IR (neat): 2922 (mCAH), 1736 (mCAH, ester) cm1; 1H NMR(500 MHz, CDCl3) d 8.00 (d, 2H, J = 8.30 Hz, Haroma.-2), 7.27 (d, 2H,J = 8.85 Hz, H aroma.-3), 5.70 (d, 1H, J = 7.50 Hz, H-1), 3.66 (s, 3H,OMe), 3.66-3.58 (m, 2H, H-6a, H-6b), 3.56 (s, 3H, OMe), 3.56 (s,3H, OMe), 3.48-3.45 (m, 1H, H-5), 3.37 (s, 3H, OMe), 3.37-3.27(m, 3H, H-2, H-3, H-4), 2.55-2.50 (m, 1H, Hcyclo.-1ax.), 1.88 (d,4H, J = 10.9 Hz, Hcyclo.-2 equiv, Hcyclo.-3 equiv), 1.49-1.42 (m, 2H,Hcyclo.-2ax.), 1.32-1.23 (m, 7H, Hcyclo.-4ax., CH3-CH2-CH2-CH2-),1.09-1.01 (m, 2H, Hcyclo.-3ax.), 0.90 (t, 3H, J = 6.95 Hz, CH3-CH2-CH2-CH2-); 13C NMR (125 MHz, CDCl3) d 164.91 (Ph-CO),154.03 (Caroma.-4), 130.15 (Caroma.-2), 126.98 (Caroma.-3), 126.95(Caroma.-1), 94.60 (C-1), 86.58, 82.92, 78.84 (C-2), 75.40 (C-5),70.64 (C-6), 61.08 (OMe), 60.81 (OMe), 60.55 (OMe), 59.37(OMe), 44.93 (Ccyclo.-1), 37.36, 37.17, 34.11 (Ccyclo.-2), 33.55(Ccyclo.-3), 29.33, 23.13, 14.27 (CH3-CH2-CH2-CH2-).Anal. Calcd for C27H42O70.5H2O: C, 66.50; H, 8.89. Found: C,66.64; H, 8.74. |