2,2-diethoxypropane

Conditions: temp:80.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of 7.45 g of 2',6'-difluoro-2-(3-pyridyl)acetophenone oxime in 170 ml of xylene is mixed with 8.00 g of diethoxypropane and then heated to 80° C. with stirring. After a clear solution has formed, 0.20 g of pulverised Amberlyst® A15 is added and the entire mixture is heated to reflux temperature. After 6 hours, the reaction mixture is subjected to clarifying filtration through Celite® and the filtrate is freed of excess solvent at 60° C. in a water jet vacuum. After drying in a high vacuum, 2',6'-difluoro-2-(3-pyridyl)acetophenone O-(1-ethoxy-1-methylethyl)oxime is obtained as an E/Z isomer mixture in the form of a yellow oil. On chromatographic separation on silica gel using n-hexane/ethyl acetate (3:1), the E isomer [1H-NMR (CDCl3, 200 MHz): 1.428 ppm (s, --C(CH3)2)] is obtained first in the form of slightly yellowish oils. After a clear solution has formed 0.20 g of pulverised Amberlyst® A15 is added the entire mixture is heated to reflux temperature filtration through Celite® is freed of excess solvent at 60° C. in a water jet vacuum After drying in a high vacuum

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 100 ml stainless steel autoclave was charged with 2.2 g (20 mmol) of resorcin, 5.28 g (40 mmol) of acetone diethyl acetal, 9.2 g (200 mmol) of ethanol, 0.2 g (2 mmol) of conc. sulfuric acid and 40 ml of toluene, then sealed and allowed to react at 100° C. for 3 hours. After similar working up as in Example 45, 2.42 g (51.3%) of 2-ethoxy-7-hydroxy-2,4,4-trimethylchroman was obtained. sealed to react at 100° C. for 3 hours