Br[CH2:2][CH:3]1[CH:7]([CH2:8]Br)[O:6][C:5](=[O:10])[O:4]1.N12CCCNC1C=CCCC2.[CH3:22][OH:23].C([O:26][CH2:27]C)C.CCCCCC>C(Cl)Cl>[CH3:22][O:23][C:7]1([CH3:8])[C:3]([O:26][CH3:27])([CH3:2])[O:4][C:5](=[O:10])[O:6]1A mixture of 4,5-dibromomethyl-1,3-dioxolan-2-one (1.21 g, 4.4 mmole) and 1,8-diazabicyclo[5.4.0]undec-5-ene (1.31 ml, 8.8 mmole) in CH2Cl2 (25.0 ml) was stirred at 20° C. for 4 h. Methanol (2.0 ml, 49 mmole) was then added and the mixture was stirred for 1 h at 20° C. Flash chromato graphy (ethyl ether-hexane eluent) of the mixture yielded 4,5-dimethyoxy-4,5-dimethyl-1,3-dioxolan-2-one as a colorless crystalline solid (0.208 g, 42%): mp 76°-77° C.; IR (KBr) 2980, 2945, 1803, 1790, 1358, 1279, 1167, 1023, 990 cm-1 ; 'H NMR (CDCl3) 1.55(s, 1 H), 3.48 (s, 1H); Anal. C7H12O5 calcd. C 47.73, H 6.87, obsd. C47.69, H 6.49.
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