1,1-diethoxy-3-methylbut-2-ene

Conditions: temp:140.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 83.8 g 4-hydroxy-acetophenone and 0.576 g anhydrous potassium carbonate were placed in 600 ml xylol in a argon atmosphere and heated to 140° C. 162.3 g 1,1-diethoxy-3-methyl-2-butene (77.9% in ethanol) was added in drops over 5 hours to this boiling solution with continuous distillation of the ethanol formed. After the solution had been stirred for 18 hours at 140° C., it was cooled to 20° C. and the organic phase was washed with 200 ml NaOH (5%) and concentrated in a vacuum. The raw product (orange-coloured oil) is distilled under a high vacuum (2.8 mbar/143° C.). The 6-acetyl-2,2-dimethyl-2H-1-benzopyran distillate obtained (90.2 g, 71.3% yield) had a content of 94.9%. formed it was cooled to 20° C. the organic phase was washed with 200 ml NaOH (5%) concentrated in a vacuum The raw product (orange-coloured oil) is distilled under a high vacuum (2.8 mbar/143° C.)

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

Procedure: Bull. Soc. Fr. 1965, 1007-1014 discloses the use of phosphoric acid. 3-Methyl-2-butenal is stirred with ethanol, triethyl orthoformate and phosphoric acid at room temperature for 40 hours. The reaction mixture is then taken up in ether, washed with 0.5 N aqueous ammonia and dried over sodium sulfate. Subsequent distillation affords 3-methyl-2-butenal diethyl acetal in a yield of 65%. washed with 0.5 N aqueous ammonia dried over sodium sulfate Subsequent distillation

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

Procedure: A 500-mL, 3-necked, round-bottomed flask topped with a distilling head, internal temperature probe/argon inlet, and an overhead stirrer was sequentially charged with the title A compound, 1,1-diethoxy-3-methyl-2-butene (26.59 g, 168.00 mmol), p-xylene (300 mL), 4-cyanophenol (15.00 g, 125.92 mmol), and 3-picoline (3.0 mL, 2.870 g, 30.83 mmol). The reaction mixture was rapidly stirred. The internal temperature was rapidly brought up to 115° C. and then slowly raised in order to distill off the ethanol formed during the reaction. A 500-mL, 3-necked, round-bottomed flask topped with a distilling head, internal temperature probe/argon inlet, and an overhead stirrer was rapidly brought up to 115° C. slowly raised in order to distill off the ethanol formed during the reaction

Conditions: temp:4.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Under an argon atmosphere, a 250-mL, round-bottomed flask equipped with a stir bar was charged with abs. ethanol (52 mL, 892 mmol, 5.0 eq). The flask was cooled to 4° C. (internal) in an ice bath. Triethyl orthoformate (29.7 mL, 178 mmol, 1.0 eq) was added followed by 3-methyl-2-butenal (17.2 mL, 178 mmol, 1.0 eq). The resulting clear, colorless solution was further cooled to 2° C. (internal). Potassium hydrogen sulfate (1.277 g, 9.38 mmol, 0.05 eq) was then added in one portion, resulting in an immediate exotherm to 10° C. The heterogeneous mixture was allowed to warm to 21° C. (internal) over 45 minutes (within 20 minutes, the mixture became slightly cloudy) and then stirred for an additional 15 minutes. The reaction mixture was then filtered and the remaining solid rinsed with abs. ethanol (5 mL). To the resulting clear, colorless solution was added anhydrous potassium carbonate (2.615 g, 18.92 mmol). The mixture was stirred for one hour before filtering off the potassium carbonate. The solid was rinsed with abs. ethanol (5 mL) and the filtrate was vacuum distilled (172 mm Hg) through a Vigereux column (13.5 cm) to produce 24.14 g (85% yield) of the title compound (boiling point 115°-119° C.). Under an argon atmosphere, a 250-mL, round-bottomed flask equipped with a stir bar was charged with abs The resulting clear, colorless solution was further cooled to 2° C. (internal) resulting in an immediate exotherm to 10° C to warm to 21° C. (internal) over 45 minutes (within 20 minutes The reaction mixture was then filtered the remaining solid rinsed with abs The mixture was stirred for one hour before filtering off the potassium carbonate The solid was rinsed with abs distilled (172 mm Hg) through a Vigereux column (13.5 cm)

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

Procedure: 0.1 Part of the reaction product, 1.74 parts of benzene, and 0.00018 part of benzoic acid were charged into a sealed tube, and reacted at 250°C. for 10 minutes. The product was subjected to gas chromatography analysis. It was thus confirmed that 3,7,11,15,19-pentamethyl-2,6-eicosadienal was obtained at the selectivity of 69.5% to the originally fed β-methyl-crotonaldehyde diethylacetal. The analytical value of the resulting acetal and aldehyde is shown in Table 16. reacted at 250°C. for 10 minutes

Conditions: temp:140.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 83.8 g 4-hydroxy-acetophenone and 0.576 g anhydrous potassium carbonate were placed in 600 ml xylol in a argon atmosphere and heated to 140° C. 162.3 g 1,1-diethoxy-3-methyl-2-butene (77.9% in ethanol) was added in drops over 5 hours to this boiling solution with continuous distillation of the ethanol formed. After the solution had been stirred for 18 hours at 140° C., it was cooled to 20° C. and the organic phase was washed with 200 ml NaOH (5%) and concentrated in a vacuum. The raw product (orange-coloured oil) is distilled under a high vacuum (2.8 mbar/143° C.). The 6-acetyl-2,2-dimethyl-2H-1-benzopyran distillate obtained (90.2 g, 71.3% yield) had a content of 94.9%. formed it was cooled to 20° C. the organic phase was washed with 200 ml NaOH (5%) concentrated in a vacuum The raw product (orange-coloured oil) is distilled under a high vacuum (2.8 mbar/143° C.)

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

Procedure: Bull. Soc. Fr. 1965, 1007-1014 discloses the use of phosphoric acid. 3-Methyl-2-butenal is stirred with ethanol, triethyl orthoformate and phosphoric acid at room temperature for 40 hours. The reaction mixture is then taken up in ether, washed with 0.5 N aqueous ammonia and dried over sodium sulfate. Subsequent distillation affords 3-methyl-2-butenal diethyl acetal in a yield of 65%. washed with 0.5 N aqueous ammonia dried over sodium sulfate Subsequent distillation