2-溴-2-(甲基)环己酮

反应条件: temp:0.00; pressure:0.00; stir:

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: A solution of 15 g (0.134 mol) of 2-methyl-1-cyclohexanone (7) and 23.84 g (0.134 mol) of N-bromosuccinimide in 150 mL of carbon tetrachloride was stirred and heated to reflux for 12 h under argon. The mixture was cooled to room temperature, filtered through Celite to remove succinimide and the filter cake was washed with 150 mL of ether. The filtrate was concentrated to give 25.6 g (100% yield) of 2-bromo-2-methyl-1-cyclohexanone. 1H NMR δ 3.21 (td, J=16 Hz, 8 Hz, 1 H, CH--CO), 2.36 (m, 2 H), 2.06 (m, 2 H), 1.82 (s, 3 H, Me), 1.77 (m, 2 H), 1.62 (m, 1 H). heated to reflux for 12 h under argon filtered through Celite to remove succinimide the filter cake was washed with 150 mL of ether The filtrate was concentrated

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: Aldehydes 4B and 4C were synthesized by a modification of the procedure reported by Corey and Erickson (Corey, E. J. and Erickson, B. W. (1971) "Oxidative hydrolysis of 1,3-dithiane derivatives to carbonyl compounds using N-halosuccimide reagent," J. Org. Chem. 36(3):553-560) which is depicted in Scheme 4. Bromination of 2-methylcyclohexanone (7) with 1 equivalent of N-bromosuccinimide (Rinne, W. W. et al., "New methods of preparation of 2-methylcyclohexen-1-one," J. Am. Chem. Soc. (1950) 72:5759-5760) in refluxing CCl4 for 12 hours gave quantitative yield of 2-bromo-2-methylcyclohexanone. Dehydrobromination of this bromide with three equivalents of Li2CO3 and three equivalents of LiBr in N,N-dimethylformamide (DMF) (Stotter, P. L. and Hill, K. A., "α Halocarbonyl Compounds. E. A Position-Specific Preparation of α-Bromo Ketones by Bromination of Lithium Enolates. A Position-Specific Introduction of α, β-Unsaturation into Unsymmetrical Ketones,"J. Org. Chem. (1973) 38:2576-2578) at 130° C. for 3 h provided a 72% yield of 2-methyl-2-cyclohexen-1-one (8). A 1,2-addition reaction of 8 with 1.5 equivalents of lithiated 1,3-dithiane [generated from 1,3-dithiane (9) with n-BuLi in THF] in THF at -10° C. to give a 96% yield of the 1,2-adduct 10. Rearrangement of 10 with 1 % sulfuric acid in p-dioxane (52% yield) followed by removal of the dithiane protecting group of the resulting alcohol, 11, with N-chlorosuccinimide (NCS) and silver nitrate in acetonitrile-water gave aldehyde 4B (50% yield). Alcohol 4B is not a stable compound and decomposes upon standing at room temperature in a few days. A more stable material, 4C, was synthesized in a better yield from the rearrangement reaction of 10 in formic acid-THF in the presence of catalytic amount of p-toluenesulfonic acid (70% yield) followed by removal of the dithiane moiety with NCS-AgNO3 (59% yield) (Scheme 4). In the formic acid rearrangement reaction, besides the desired product, 1-[2-(1,3-dithianyl)]-3-formyloxy-2-methyl-1-cyclohexene, 9% yield of 3-[2-(1,3-dithianyl)]-2-methyl-2-cyclohexen-1-ol (11) was also isolated.

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: Aldehydes 4B and 4C were synthesized by a modification of the procedure reported by Corey and Erickson (Corey, E. J. and Erickson, B. W. (1971) "Oxidative hydrolysis of 1,3-dithiane derivatives to carbonyl compounds using N-halosuccimide reagent," J. Org. Chem. 36(3):553-560) which is depicted in Scheme 4. Bromination of 2-methylcyclohexanone (7) with 1 equivalent of N-bromosuccinimide (Rinne, W. W. et al., "New methods of preparation of 2-methylcyclohexen-1-one," J. Am. Chem. Soc. (1950) 72:5759-5760) in refluxing CCl4 for 12 hours gave quantitative yield of 2-bromo-2-methylcyclohexanone. Dehydrobromination of this bromide with three equivalents of Li2CO3 and three equivalents of LiBr in N,N-dimethylformamide (DMF) (Stotter, P. L. and Hill, K. A., "α Halocarbonyl Compounds. E. A Position-Specific Preparation of α-Bromo Ketones by Bromination of Lithium Enolates. A Position-Specific Introduction of α, β-Unsaturation into Unsymmetrical Ketones,"J. Org. Chem. (1973) 38:2576-2578) at 130° C. for 3 h provided a 72% yield of 2-methyl-2-cyclohexen-1-one (8). A 1,2-addition reaction of 8 with 1.5 equivalents of lithiated 1,3-dithiane [generated from 1,3-dithiane (9) with n-BuLi in THF] in THF at -10° C. to give a 96% yield of the 1,2-adduct 10. Rearrangement of 10 with 1 % sulfuric acid in p-dioxane (52% yield) followed by removal of the dithiane protecting group of the resulting alcohol, 11, with N-chlorosuccinimide (NCS) and silver nitrate in acetonitrile-water gave aldehyde 4B (50% yield). Alcohol 4B is not a stable compound and decomposes upon standing at room temperature in a few days. A more stable material, 4C, was synthesized in a better yield from the rearrangement reaction of 10 in formic acid-THF in the presence of catalytic amount of p-toluenesulfonic acid (70% yield) followed by removal of the dithiane moiety with NCS-AgNO3 (59% yield) (Scheme 4). In the formic acid rearrangement reaction, besides the desired product, 1-[2-(1,3-dithianyl)]-3-formyloxy-2-methyl-1-cyclohexene, 9% yield of 3-[2-(1,3-dithianyl)]-2-methyl-2-cyclohexen-1-ol (11) was also isolated.

反应条件: temp:0.00; pressure:0.00; stir:

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: A solution of 15 g (0.134 mol) of 2-methyl-1-cyclohexanone (7) and 23.84 g (0.134 mol) of N-bromosuccinimide in 150 mL of carbon tetrachloride was stirred and heated to reflux for 12 h under argon. The mixture was cooled to room temperature, filtered through Celite to remove succinimide and the filter cake was washed with 150 mL of ether. The filtrate was concentrated to give 25.6 g (100% yield) of 2-bromo-2-methyl-1-cyclohexanone. 1H NMR δ3.21 (td, J=16 Hz, 8 Hz, 1H, CH—CO), 2.36 (m, 2H), 2.06 (m, 2H), 1.82 (s, 3H, Me), 1.77 (m, 2H), 1.62 (m, 1H). heated to reflux for 12 h under argon filtered through Celite to remove succinimide the filter cake was washed with 150 mL of ether The filtrate was concentrated

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: Aldehydes 4B and 4C were synthesized by a modification of the procedure reported by Corey and Erickson (Corey, E. J. and Erickson, B. W. (1971) “Oxidative hydrolysis of 1,3-dithiane derivatives to carbonyl compounds using N-halosuccimide reagent,” J. Org. Chem. 36(3):553-560) which is depicted in Scheme 4. Bromination of 2-methylcyclohexanone (7) with 1 equivalent of N-bromosuccinimide (Rinne, W. W. et al., “New methods of preparation of 2-methylcyclohexen-1-one,” J. Am. Chem. Soc. (1950) 72:5759-5760) in refluxing CCl4 for 12 hours gave quantitative yield of 2-bromo-2-methylcyclohexanone. Dehydrobromination of this bromide with three equivalents of Li2CO3 and three equivalents of LiBr in N,N-dimethylformamide (DMF) (Stotter, P. L. and Hill, K. A., “α Halocarbonyl Compounds. II. A Position-Specific Preparation of α-Bromo Ketones by Bromination of Lithium Enolates. A Position-Specific Introduction of α, β-Unsaturation into Unsymmetrical Ketones,” J. Org. Chem. (1973) 38:2576-2578) at 130° C. for 3 h provided a 72% yield of 2-methyl-2-cyclohexen-1-one (8). A 1,2-addition reaction of 8 with 1.5 equivalents of lithiated 1,3-dithiane [generated from 1,3-dithiane (9) with n-BuLi in THF] in THF at −10° C. to give a 96% yield of the 1,2-adduct 10. Rearrangement of 10 with 1% sulfuric acid in p-dioxane (52% yield) followed by removal of the dithiane protecting group of the resulting alcohol, 11, with N-chlorosuccinimide (NCS) and silver nitrate in acetonitrile-water gave aldehyde 4B (50% yield). Alcohol 4B is not a stable compound and decomposes upon standing at room temperature in a few days. A more stable material, 4C, was synthesized in a better yield from the rearrangement reaction of 10 in formic acid-THF in the presence of catalytic amount of p-toluenesulfonic acid (70% yield) followed by removal of the dithiane moiety with NCS-AgNO3 (59% yield) (Scheme 4). In the formic acid rearrangement reaction, besides the desired product, 1-[2-(1,3-dithianyl)]-3-formyloxy-2-methyl-1-cyclohexene, 9% yield of 3-[2-(1,3-dithianyl)]-2-methyl-2-cyclohexen-1-ol (11) was isolated.

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: A solution of 15 g (0.134 mol) of 2-methyl-1-cyclohexanone (7) and 23.84 g (0.134 mol) of N-bromosuccinimide in 150 mL of carbon tetrachloride was stirred and heated to reflux for 12 h under argon. The mixture was cooled to room temperature, filtered through Celite to remove succinimide and the filter cake was washed with 150 mL of ether. The filtrate was concentrated to give 25.6 g (100% yield) of 2-bromo-2-methyl-1-cyclohexanone. 1H NMR δ 3.21 (td, J=16 Hz, 8 Hz, 1 H, CH--CO), 2.36 (m, 2 H), 2.06 (m, 2 H), 1.82 (s, 3 H, Me), 1.77 (m, 2 H), 1.62 (m, 1 H). heated to reflux for 12 h under argon filtered through Celite to remove succinimide the filter cake was washed with 150 mL of ether The filtrate was concentrated

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: Aldehydes 4B and 4C were synthesized by a modification of the procedure reported by Corey and Erickson (Corey, E. J. and Erickson, B. W. (1971) "Oxidative hydrolysis of 1,3-dithiane derivatives to carbonyl compounds using N-halosuccimide reagent," J. Org. Chem. 36(3):553-560) which is depicted in Scheme 4. Bromination of 2-methylcyclohexanone (7) with 1 equivalent of N-bromosuccinimide (Rinne, W. W. et al., "New methods of preparation of 2-methylcyclohexen-1-one," J. Am. Chem. Soc. (1950) 72:5759-5760) in refluxing CCl4 for 12 hours gave quantitative yield of 2-bromo-2-methylcyclohexanone. Dehydrobromination of this bromide with three equivalents of Li2CO3 and three equivalents of LiBr in N,N-dimethylformamide (DMF) (Stotter, P. L. and Hill, K. A., "α Halocarbonyl Compounds. E. A Position-Specific Preparation of α-Bromo Ketones by Bromination of Lithium Enolates. A Position-Specific Introduction of α, β-Unsaturation into Unsymmetrical Ketones,"J. Org. Chem. (1973) 38:2576-2578) at 130° C. for 3 h provided a 72% yield of 2-methyl-2-cyclohexen-1-one (8). A 1,2-addition reaction of 8 with 1.5 equivalents of lithiated 1,3-dithiane [generated from 1,3-dithiane (9) with n-BuLi in THF] in THF at -10° C. to give a 96% yield of the 1,2-adduct 10. Rearrangement of 10 with 1 % sulfuric acid in p-dioxane (52% yield) followed by removal of the dithiane protecting group of the resulting alcohol, 11, with N-chlorosuccinimide (NCS) and silver nitrate in acetonitrile-water gave aldehyde 4B (50% yield). Alcohol 4B is not a stable compound and decomposes upon standing at room temperature in a few days. A more stable material, 4C, was synthesized in a better yield from the rearrangement reaction of 10 in formic acid-THF in the presence of catalytic amount of p-toluenesulfonic acid (70% yield) followed by removal of the dithiane moiety with NCS-AgNO3 (59% yield) (Scheme 4). In the formic acid rearrangement reaction, besides the desired product, 1-[2-(1,3-dithianyl)]-3-formyloxy-2-methyl-1-cyclohexene, 9% yield of 3-[2-(1,3-dithianyl)]-2-methyl-2-cyclohexen-1-ol (11) was also isolated.