1,4,5,6-TETRAHYDRO-CYCLOPENTAPYRAZOLE-3-CARBOXYLIC ACID

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: 504 g of a solution of 240 g of propionaldehyde in 264 g of diethoxyacetaldehyde (glyoxal(mono)diethylacetal) are run into a mixture of 48 g of dimethylamine in 72 g of water and 80 g of propionic acid at 40° C. in the course of 30 minutes, while stirring. The reaction mixture is then stirred for a further 3 hours. After the lower aqueous phase has been separated off, fractional distillation of the organic phase gives 237 g (68.9% of theory) of 2-methyl-4,4-diethoxybut-2-enal of boiling point 67°-69° C./8 mbar. The reaction mixture is then stirred for a further 3 hours After the lower aqueous phase has been separated off fractional distillation of the organic phase

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

Procedure: The mixture of 10.2 g of 2,2-diethoxy acetaldehyde, 27.8 g of methyl triphenylphosphoranylidene-acetate and 130 ml of benzene is refluxed for 15 hours and evaporated. The residue is triturated with diethyl ether, filtered and the filtrate evaporated. The residue is allowed to stand overnight in the refrigerator, triturated with the minimum amount of diethyl ether, the suspension filtered, the filtrate evaporated, the residue distilled and the fraction boiling at 50°-54°/0.1 mm Hg collected, to yield the 4,4-diethoxy-crotonic acid methyl ester. is refluxed for 15 hours evaporated The residue is triturated with diethyl ether filtered the filtrate evaporated triturated with the minimum amount of diethyl ether the suspension filtered the filtrate evaporated the residue distilled the fraction boiling at 50°-54°/0.1 mm Hg collected

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

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

Procedure: 504 g of a solution of 240 g of propionaldehyde in 264 g of diethoxyacetaldehyde (glyoxal(mono)diethylacetal) are run into a mixture of 48 g of dimethylamine in 72 g of water and 80 g of propionic acid at 40° C. in the course of 30 minutes, while stirring. The reaction mixture is then stirred for a further 3 hours. After the lower aqueous phase has been separated off, fractional distillation of the organic phase gives 237 g (68.9% of theory) of 2-methyl-4,4-diethoxybut-2-enal of boiling point 67°-69° C./8 mbar. The reaction mixture is then stirred for a further 3 hours After the lower aqueous phase has been separated off fractional distillation of the organic phase

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

Procedure: The mixture of 10.2 g of 2,2-diethoxy acetaldehyde, 27.8 g of methyl triphenylphosphoranylidene-acetate and 130 ml of benzene is refluxed for 15 hours and evaporated. The residue is triturated with diethyl ether, filtered and the filtrate evaporated. The residue is allowed to stand overnight in the refrigerator, triturated with the minimum amount of diethyl ether, the suspension filtered, the filtrate evaporated, the residue distilled and the fraction boiling at 50°-54°/0.1 mm Hg collected, to yield the 4,4-diethoxy-crotonic acid methyl ester. is refluxed for 15 hours evaporated The residue is triturated with diethyl ether filtered the filtrate evaporated triturated with the minimum amount of diethyl ether the suspension filtered the filtrate evaporated the residue distilled the fraction boiling at 50°-54°/0.1 mm Hg collected

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

Procedure: The mixture of 10.2 g of 2,2-diethoxy acetaldehyde, 27.8 g of methyl triphenylphosphoranylidene-acetate and 130 ml of benzene is refluxed for 15 hours and evaporated. The residue is triturated with diethyl ether, filtered and the filtrate evaporated. The residue is allowed to stand overnight in the refrigerator, triturated with the minimum amount of diethyl ether, the suspension filtered, the filtrate evaporated, the residue distilled and the fraction boiling at 50°-54°/0.1 mm Hg collected, to yield the 4,4-diethoxy-crotonic acid methyl ester. is refluxed for 15 hours evaporated The residue is triturated with diethyl ether filtered the filtrate evaporated triturated with the minimum amount of diethyl ether the suspension filtered the filtrate evaporated the residue distilled the fraction boiling at 50°-54°/0.1 mm Hg collected

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

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

Procedure: The isoquinolin-8-yl system can be prepared from the appropriately substituted benzylamine by cyclocondensation with diethoxy-acetaldehyde (see, for example, K. Kido and Y. Watanabe, Chemical & Pharmaceutical Bulletin, 35(12), 4964-6; 1987). Alternatively 8-bromo-isoquinoline (prepared by the method of F. T. Tyson, J.A.C.S., 1939, 61, N. Briet et al., Tetrahedron (2002), 58(29), 5761-5766 or W. D. Brown, et al., Synthesis (2002), (1), 83-86. 183 can be subjected to N-oxidation and rearrangement to give 8-bromo-2H-isoquinolin-1-one. This can be N-methylated to give 8-bromo-2-methyl-2H-isoquinolin-1-one, an appropriate intermediate for the 2-methyl-1-oxo-1,2-dihydroisoquinolin-8-yl system. Brown, et al., Synthesis (2002), (1), 83-86

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

Procedure: The isoquinolin-8-yl system can be prepared from the appropriately substituted benzylamine by cyclocondensation with diethoxy-acetaldehyde (see, for example, K. Kido and Y. Watanabe, Chemical & Pharmaceutical Bulletin, 35(12), 4964-6; 1987). Alternatively 8-bromo-isoquinoline (prepared by the method of F. T. Tyson, J.A.C.S., 1939, 61, N. Briet et al., Tetrahedron (2002), 58(29), 5761-5766 or W. D. Brown, et al., Synthesis (2002), (1), 83-86. 183 can be subjected to N-oxidation and rearrangement to give 8-bromo-2H-isoquinolin-1-one. This can be N-methylated to give 8-bromo-2-methyl-2H-isoquinolin-1-one, an appropriate intermediate for the 2-methyl-1-oxo-1,2-dihydroisoquinolin-8-yl system. Brown, et al., Synthesis (2002), (1), 83-86

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

Procedure: 504 g of a solution of 240 g of propionaldehyde in 264 g of diethoxyacetaldehyde (glyoxal(mono)diethylacetal) are run into a mixture of 48 g of dimethylamine in 72 g of water and 80 g of propionic acid at 40° C. in the course of 30 minutes, while stirring. The reaction mixture is then stirred for a further 3 hours. After the lower aqueous phase has been separated off, fractional distillation of the organic phase gives 237 g (68.9% of theory) of 2-methyl-4,4-diethoxybut-2-enal of boiling point 67°-69° C./8 mbar. The reaction mixture is then stirred for a further 3 hours After the lower aqueous phase has been separated off fractional distillation of the organic phase