Synthesis Of Bicyclo[3.2.1]octane-2,4-dione

Bicyclo[3.2.1]octane-2,4-dione is the key intermediate of novel herbicide 3-[2-chloro-4-(methylsulfonyl)benzoyl]bicyclo[3.2.1]octane-2,4-dione,with large domestic and external demand.Currently,our country doesn't grasp the key production technology.Improving the synthesis process is very urgent.Reported mainly synthetic routes are using pentachloropropane and cyclopentadiene as a starting material.After 4 to 7 steps reaction,products are purified by silica gel column to obtain pure product in 45%yield.The main problems of reported processes are the poor atom economy,waste discharge large and low yield,which make them unsuitable for industrial production.Hence,exploring an economic,environmental,suitable industrial production process of bicyclo[3.2.1]octane-2,4-dione is very important.Norbornene is a chemical material used widely,which is prepared by the Diels-Alder reaction of ethylene and dicyclopentadiene.In this paper,use the readily available and inexpensive norbornene as starting materials.Through hydration,oxidation,Mannich reaction and de-amine reaction,B aeyer-Villiger reaction,condensation reaction and,ultimately,the total yield of bicyclo[3.2.1]octane-2,4-dione is 53.9%.Study the process of sulfuric acid catalyzing hydration of norbornene.Solve the problem of easy sublimation of norbornene by introducing sublimation inhibitors.The yield of 2-norbornanol reach to 94.5%and achieve the recycling of the sulfuric acid.Study the process of the 4-OH-TEMPO,CuCl and TBN efficient catalytic oxidation of 2-norbornanol and achieve the recycling of the catalysts.The conversion rate reach to 100%and the yield reach to 93%.Solve the shortcomings of low conversion of oxygen oxidation.Develop a more economy process of producing 2-norbornanone.Study acetic acid,secondary amine and sulfuric acid catalyze a pot reaction of 2-norbornanone and formaldehyde to 3-methylene-2-norbornanone.The yield reach to 92%.Use paraformaldehyde instead of formaldehyde aqueous solution to reduce waste water.Achieve the recycling of acetic acid,sulfuric acid and diethylamine after the steam distillation,which reduce the cost of production and wastewater discharge.Study sulfuric acid catalyze a pot reaction of 3-methylene-2-norbornanone,hydrogen peroxide and methanol to 3-acetyl-cyclopentanecarboxylic acid methyl ester.The yield reach to 91%.Explore the post-processing method of extracting after distilling methanol,which improves the yield and reduces wastewater discharge.Study sodium methoxide catalyze self-condensation reaction of 3-acetyl-cyclopentanecarboxylic acid methyl ester to bicyclo[3.2.1]octane-2,4-dione.The yield reach to 73.4%.Provide an economical,environmentally friendly,high yield,suitable for industrial production process for bicyclo[3.2.1]octane-2,4-dione.The products of the reactions are confirmed by mass spectroscopy(MS),1HNMR and 13CNMR.