[CH3:1][O:2][C:3]([C:5]1[O:6][C:7]([CH3:12])=[C:8]([CH2:10][OH:11])[CH:9]=1)=[O:4].[I:13][C:14]1[CH:19]=[CH:18][C:17](O)=[CH:16][CH:15]=1.C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.CC(OC(/N=N/C(OC(C)C)=O)=O)C>O1CCCC1>[CH3:1][O:2][C:3]([C:5]1[O:6][C:7]([CH3:12])=[C:8]([CH2:10][O:11][C:17]2[CH:18]=[CH:19][C:14]([I:13])=[CH:15][CH:16]=2)[CH:9]=1)=[O:4]
A solution of 4-hydroxymethyl-5-methyl-furan-2-carboxylic acid methyl ester (16) (1.14 g) in tetrahydrofuran (15 mL) was cooled to 0° C. with stirring and treated with 4-iodophenol (4.6 g), triphenylphosphine (5.5 g) and diisopropylazodicarboxylate (4.2 g). After 10 minutes the cooling bath was removed. After 3 hours the reaction mixture was concentrated in vacuo and taken up in ethyl acetate (100 mL) and washed successively with water (100 mL), 1.0 M aqueous sodium hydroxide solution (100 mL), dried and concentrated in vacuo. The residue was purified by flash chromatography eluting with ethyl acetate/hexane (1:4 by volume) to give compound 20 as a white solid (1.58 g).
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