Acetic Acid → (2,2-Dimethyl-5-oxo-[1,3]dioxolan-4-ylidene)-acetic acid

Participants

Reaction Steps

The crude (Z)-2,2-dimethyl-5-(tert-butyldimethylsilyloxycarbonyl-methylene)-1,3-dioxolan-4-one (72.4 mmol) in tetrahydrofuran (50 ml) was treated at 22° C. with acetic acid (13 ml, 0.227 mmol) followed by 73 ml (73.0 mmol) of a 1M solution of tetrabutylammonium fluoride in tetrahydrofuran. After 1 h at 22° C., the reaction mixture was diluted with ethyl acetate (500 ml), washed with water, brine and dried (anhydrous magnesium sulfate). Evaporation of the solvent under reduced pressure and trituration of the residual solid with toluene (50 ml) gave 7.70 g (62% yield for 3 steps) of the title Z-isomer as a white crystalline solid. Concentration of the mother liquors yielded another 0.2 g of a 75:25 mixture of Z and E isomers. Z-Isomer; 1H NMR (400 MHz, CDCl3) δ: 1.78 (s, 3), 5.89 (s, 1). E-Isomer: 1H NMR (400 MHz, CDCl3) δ: 1.80 (s, 3), 6.03 (s, 1).

Provenance & Evidence