91424-39-4

91424-40-7

The general procedure for the synthesis of 3-tert-butyldimethylsilyloxyglutaric anhydride from diethyl 3-(tert-butyldimethylsilyloxy)glutarate is as follows: B.4 - [[(dimethylethyl)dimethylsilyl]oxy]dihydro-2H-pyran-2,6(3H)-dione Part A: Methylsilyl ether (theoretical value 63.6 g, 200 mmol) was dissolved in methanol (200 ml), NaOH pellets (16.0 g, 400 mmol) were added and stirred at room temperature for 18 h under argon protection. The turbid yellow solution was evaporated to dryness and dried under vacuum to give the disodium salt as a light yellow solid. The disodium salt (42.1 g) was suspended in benzene (400 ml), acetic anhydride (200 ml) was added and refluxed under argon protection for 1.5 hours. The brown mixture was concentrated in vacuum and the residue was partitioned between ethyl acetate and half-saturated and NaHCO3 solution. The organic phase was washed with half-saturated and NaHCO3 and saturated NaCl solution, dried over Na2SO4 and evaporated to give the crude title anhydride as a brown solid. The crude product was dissolved in ether, Darco (3 g) was added, filtered through diatomaceous earth and evaporated. The crystallized residue was ground with cold hexane to give the pure title anhydride (33.26 g, 68% overall yield, based on diethyl 3-hydroxyglutarate) as white plate-like crystals with melting point 205 °C (decomposed) and 77°-78 °C (undecomposed).13C-NMR (15 MHz, CDCl3) δ: 5.22, 17.64, 25.31, 38.88, 61.87 , 165.26 ppm.