| Due to the electron withdrawing effects of phenylsulfonyl,phenylsulfonyl α,β-unsaturated ketones is very conducive to Diels-Alder reaction as the dienophile of Diels-Alder reaction.Moreover the ketone carbonyl and the sulfur oxygen double bond of sulfonyl is a good type of complex formation of bidentate ligand.In addition,phenylsulfonyl a,P-unsaturated ketones can react as Hetero 1,3-dienes body in the Hetero Diels-Alder reaction,and it can also be used as acceptor in the Michael reaction.Therefore,it improve the value of the response matrix by the research of response matrix with a variety of the reaction pathway.The method for synthesis of phenylsulfonyl α,β-unsaturated ketone now:butyl lithium Law,Jones oxidation,Claisen-Schimidt condensation and so on.The application of butyl lithium Law(R:aliphatic and aromatic)is broader,and yield is higher(65-78%).However,it restricted the synthesis of the product on which aromatic ring has electron withdrawing substituents,and the experimental conditions were more harsh,and it required low temperature-78 ℃.Claisen-Schimidt condensation synthesizes brominated material by using a brominating agent Ph3P+ CH2CH2COOHBr3-.The conditions of the reaction was mild,the products were easily separated,and the brominating agent can be recycled.However,although this method can be a good synthesis of aryl substituted phenylsulfonyl α,β-unsaturated ketones,the second step of the selective a-bromination product yield rate is not high,so the yield of the unsaturated ketone not high(27-41%),while the reaction was intractable and the yield was low in the synthesis of alkyl benzene sulfonyl α,β-unsaturated ketone.These methods can be a good synthesis of aryl substituted phenylsulfonyl α,β-unsaturated ketones,but owing to refractories of the reaction,low yield of product,harsh conditions in the synthesis of alkyl benzene sulfonyl α,β-unsaturated ketone,the paper improves the previous method on this basis,we used 2,4,4,6-tetrabromo 2,5-cyclohexadiene-l-ketone instead of Ph3P+CH2CH2COOHBr3-in the synthesis of brominated products.The reaction of 2,4,4,6-tetrabromo 2,5-cyclohexadiene-l-unsaturated ketone and methyl ketone which can get high yields of 1-bromo objects can reacted at room temperature.The bromination reagent was easy synthesized,and using tribromophenol generated in the reaction reduced the cost.The yield attained 71%when R was phenyl.To further testimony of phenylsulfonyl α,β-unsaturated ketones we synthesized,we got the reaction of unsaturated ketones with cyclopentadiene by Diels-Alder reactions which successfully obtained phenylsulfonyl acetyl-bicyclo[2.2.1]-2-heptene.In addition,we have designed a new synthesis of phenylsulfonyl a,β-unsaturated ketone.The reaction route starting from phenylthioacetic acid,after the acylation,reacted with triethyl phosphono acetate under anhydrous MgCl2-TEA system,4-phenylthio-2-two ethoxycarbonyl phosphono-3-oxo butyric acid Ester was synthesized,and then obtained by the hydrolysis of β-phenylthio carbonyl substituted phosphonate by which can be prepared phenylthio substituted α,β-unsaturated ketone by Homer-Wadoms-Emmons reaction,and then through the oxidation of sulfone or sub-Sulfone got phenylsulfonyl α,β-unsaturated ketone,or through oxidation of sulfur got sulfone or sulfoxide,and then reacted with different aldehydes and ketones,finally generated unsaturated ketones.phenylthio acetyl chloride and triethyl phosphono acetate must be carried out under a nitrogen atmosphere,Optimum conditions:methylene chloride as solvent,triethylamine as the acid,magnesium chloride as catalyst,dropping chloride in ice bath,the reaction has mild conditions,short reaction time,and can be completed by being stirried 4h at room temperature.Product can be extracted with dichloromethane from the water under acidic conditions,the organic phase washed with saturated sodium bicarbonate solution,saturated salt water and twice.We obtained yellow transparent liquid by column chromatography after solvent evaporated,the yield was 51.3%,the yield of β-carbonyl phosphonates was 83.5%after hydrolysis. |
