2,2-dimethyl-1,3-benzodioxole

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

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

Procedure: A mixture of catechol (55 g, 0.5 moles), acetone (150 ml), benzene (150 ml) and p-toluenesulfonic acid (15 mg) was refluxed in a Soxlet extractor containing 140 g of baked 4Å molecular sieves for 24 hours, as described in E. R. Cole, et al., Aust. J. Chem. 33, 675 (1980). The sieves were replaced with fresh sieves and refluxing continued for another 24 hours. The solvents were removed in vacuo and the residue was triturated with 1 liter of hexane. The light yellow solution was decanted and washed with 10% NAOH until the washes were colorless. The organic layer was dried (Na2SO4) and evaporated to 32.4 g (43%) of title compound as an oil which was used without further purification. 1H-NMR(CDCl3): δ=1.73 (s,6H); 6.78 (s,4H). was refluxed in a Soxlet extractor containing 140 g of baked 4Å molecular sieves for 24 hours refluxing The solvents were removed in vacuo the residue was triturated with 1 liter of hexane The light yellow solution was decanted washed with 10% NAOH until the washes The organic layer was dried (Na2SO4) evaporated to 32.4 g (43%) of title compound as an oil which was used without further purification

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

Procedure: A mixture of catechol (55 g, 0.5 moles), acetone (150 ml), benzene (150 ml) and p-toluenesulfonic acid (15 mg) was refluxed in a Soxlet extractor containing 140 g of baked 4Å molecular sieves for 24 hours, as described in E. R. Cole, et al., Aust. J. Chem. 33, 675 (1980). The sieves were replaced with fresh sieves and refluxing continued for another 24 hours. The solvents were removed in vacuo and the residue was triturated with 1 liter of hexane. The light yellow solution was decanted and washed with 10% NAOH until the washes were colorless. The organic layer was dried (Na2SO4) and evaporated to 32.4 g (43%) of title compound as an oil which was used without further purification. 1H-NMR(CDCl3): δ=1.73 (s,6H); 6.78 (s,4H). was refluxed in a Soxlet extractor containing 140 g of baked 4Å molecular sieves for 24 hours refluxing The solvents were removed in vacuo the residue was triturated with 1 liter of hexane The light yellow solution was decanted washed with 10% NAOH until the washes The organic layer was dried (Na2SO4) evaporated to 32.4 g (43%) of title compound as an oil which was used without further purification

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

Procedure: 24 ml of nitric acid (d=1.4) in 60 ml of glacial acetic acid were added dropwise at 15°-20° C. to 39.0 g of 2,2-dimethyl-1,3-benzodioxole in 200 ml of glacial acetic acid. After stirring at room temperature for 3 hours, the mixture was poured into ice/water and extracted twice with 1 l of methylene chloride. The organic phase was washed neutral with water, dried over sodium sulfate and evaporated in vacuo. The residue, recrystallized from methanol, gave 17.0 g (33.5% of theory) of 2,2-dimethyl-5-nitro-1,3-benzodioxole of melting point 88°-90° C. extracted twice with 1 l of methylene chloride The organic phase was washed neutral with water dried over sodium sulfate evaporated in vacuo The residue, recrystallized from methanol

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

Procedure: 24 ml of nitric acid (d=1.4) in 60 ml of glacial acetic acid were added dropwise at 15°-20° C. to 39.0 g of 2,2-dimethyl-1,3-benzodioxole in 200 ml of glacial acetic acid. After stirring at room temperature for 3 hours, the mixture was poured into ice/water and extracted twice with 1 l of methylene chloride. The organic phase was washed neutral with water, dried over sodium sulfate and evaporated in vacuo. The residue, recrystallized from methanol, gave 17.0 g (33.5% of theory) of 2,2-dimethyl-5-nitro-1,3-benzodioxole of melting point 88°-90° C. extracted twice with 1 l of methylene chloride The organic phase was washed neutral with water dried over sodium sulfate evaporated in vacuo The residue, recrystallized from methanol

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

Procedure: Hydrogen chloride gas was introduced into a solution of 110.1 g of pyrocatechol in 370 ml of acetone for 2 hours while stirring and cooling with ice 10°-15° C. internal temperature, and then for an additional 30 minutes at 0° C. The mixture was poured into ice/water, made alkaline and extracted three times with 1 l of ether. The organic phase was washed neutral three times with 500 ml of water, dried over sodium sulfate and evaporated in vacuo. The residue was distilled in vacuo (b.p. 11 mm/59°-60° C.). There were obtained 39.0 g (26.0% of theory) of 2,2-dimethyl-1,3-benzodioxole. cooling with ice 10°-15° C. internal temperature extracted three times with 1 l of ether The organic phase was washed neutral three times with 500 ml of water dried over sodium sulfate evaporated in vacuo The residue was distilled in vacuo (b.p. 11 mm/59°-60° C.)

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

Procedure: Under a nitrogen atmosphere, a solution of 10.0 grams (0.091 mole) of catechol in 100 mL of toluene and 100 mL of acetone was stirred and 0.01 gram (catalyst) of para-toluenesulfonic acid was added in one portion. Upon completion of additon the reaction mixture was warmed to reflux where it was maintained during a 48 hour period. After this time the reaction mixture was cooled to ambient temperature, then it was concentrated under reduced pressure to a residue. The residue was purified with column chromatography on silica gel using petroleum ether as an eluant. The appropriate fractions were combined and concentrated under reduced pressure, yielding 3.3 grams of the subject compound. The NMR spectrum was consistent with the proposed structure. Upon completion of additon the reaction mixture was warmed to reflux where it was maintained during a 48 hour period it was concentrated under reduced pressure to a residue The residue was purified with column chromatography on silica gel concentrated under reduced pressure

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

Procedure: As depicted in Scheme 3, catechol was cyclized with acetone under catalytic conditions, affording the corresponding 2,2-dimethylbenzo[d]1,3-dioxolane (C1). Intermediate (C1) was then treated with for example lead tetraacetate ubder acidic conditions, yielding the corresponding 2,2-dimethylbenzo[3,4-d]1,3-dioxolan-5-yl acetate (C2). Intermediate (C2) was then deprotected with strong base, providing a phenolic intermediate (C3), which was in turn reacted with intermediate (B5), as taught in scheme 2, affording a compound of formula I. Example 3 set forth below describes in detail the method by which compounds of formula I were prepared as shown in scheme 3.