Acetic Acid → Z-2,2-dimethyl-5-carboxymethylene-1,3-dioxolan-4-one

The crude (Z)-2,2-dimethyl-5-(tert-butyldimethylsilyloxycarbonylmethylene)-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% 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).

1. washwashed with water, brine
2. dry with materialdried (anhydrous magnesium sulfate)
3. customEvaporation of the solvent under reduced pressure and trituration of the residual solid with toluene (50 ml)
4. customgave 7.70 g (62% for 3 steps) of the title Z-isomer as a white crystalline solid
5. customConcentration of the mother liquors yielded
6. additionanother 0.2 g of a 75:25 mixture of Z and E isomers

ORD record

ord-82735593dbc44fc7aa42b79e518a7a27

Source dataset

uspto-grants-2004_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06803378B2