Reaction #2688

Reaction equation

NaOH

2,2,6,6-Tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole

n-butyllithium

carbon dioxide

→

2,2,6,6-Tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-carboxylic acid

Solvents

Water

THF

hexane

Conditions

Workup

1. 1
   Otherprepared
2. 2
   OtherAfter attaining ambient temperature
3. 3
   WashAfter washing with ether
4. 4
   Extractionextracted with ether (2*300 mL)
5. 5
   DryingThe organic phases were dried (Na2SO4)
6. 6
   Otherevaporated
7. 7
   Otherto give the pure product

Procedure

2,2,6,6-Tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole (10.0 g, 45.0 mmol; prepared according to WO-91/12024) was dissolved in dry THF (200 mL) under an argon atmosphere. The solution was cooled to -20° C. and n-butyllithium (20.0 mL, 50.0 mmol) in hexane was added. After attaining ambient temperature, the reaction mixture was transferred onto solid carbon dioxide (150 g) and allowed to stand overnight. Water (200 mL) was added and pH was adjusted to 10 using 2M aqueous NaOH. After washing with ether, the aqueous phase was acidified with 2M hydrochloric acid to pH 2 and extracted with ether (2*300 mL). The organic phases were dried (Na2SO4) and evaporated to give the pure product.

Source