gHighly optically active 4-substituted-2(5H)-furanones 6a—6j were obtained in good yields with de≥98% by the tandem Michael addition/elimination reaction of chiral 3-bromo-2(5H)-furanone (4a), which was conveniently prepared starting from 2-furaldehyde under mild conditions. The products were identified on the basis of their sat-isfactory elemental analysis and spectroscopic data of IR, UV, 1H NMR, 13C NMR and mass spectra. The stereo-chemistry and absolute configuration of this type of compounds were established by the X-ray crystallographic study. The reaction provided a short and efficient synthesis of the interesting highly optically active 4-substituted-2(5H)-furanones containing an active pyrimidine and a purine base group.
The title compound, spiro[ 1-bromo-4-l-menthyloxy-5-oxo-6-oxa-bicyclo[3.1.0]- hexane-2,2＇-3＇-（16＇-methoxyacetatyl-4＇-l-menthyloxybutyrolactone）] 1, was obtained via tandem asymmetric double Michael addition/internal nucleophilic substitution of the chiral synthon, 5-l-menthyloxy-3-bromo-2-（5H）-furanone 2 with methoxy α-chloroacetate as a nucleophile under mild conditions, and structurally [letermined by single-crystal X-ray diffraction. Crystal data： C31H47BrO9, Mr = 643.60, orthorhombic, space group P212121. α = 9.6564（7）, b = 14.8994（11）, c = 23.6771（17） A, V= 3406.5（4） A^3, Z = 4, Dc= 1.255 g/cm^3, 2（MoKa） = 0.71073 A,μ= 1.254 mm^-1 and F（000） = 1360. The structure was refined to R =[0.0324 and wR = 0.0737 for 5123 observed reflections （I〉 2σ（I））. The crystallographic results of molecule 1 show that the interesting reaction of 2 with methoxy α-chloroacetate, in the usual manner, gave the spiro-cyclopropane skeleton with O-linked derivative containing multiple stereogenic centers 1 rather than the expected C-linked derivative.
