Iodine-catalyzed Synthesis Of Unsaturated Ketones To Polysubstituted Furans

For more than a century,the method of synthesizing furans has attracted great interest from scientists in various fields,which is enough to show the importance of these heterocyclic compounds in the synthesis of natural products and the need for more selective and versatile synthetic methods.Until now,cyclo-isomerization of alkyne-and propene-containing compounds has been explored.However,there are some limitations because these substrates which contain sensitive functional groups cannot be prepared disubstituted furans by linear isomerization,and most many transitional metal catalyzed synthesis of polysubstituted furan compounds has been reported.However,there are few reports on the use of non-metal catalyzed synthesis of polysubstituted furans.A method for synthesizing multiple substituted furans from unsaturated ketones catalyzed by iodine has not been reported so far.The advantage of this method is that a relatively good yield can be obtained with a catalytic amount of iodine,avoiding the disadvantages of low toxicity,high cost of the transition metal,and that different substituted furan combinations can be obtained according to different substrates.This article includes two parts.The first part is the synthesis of 2,4-disubstituted or 2,3,5-trisubstituted or2,3,4-trisubstituted furan compounds from ?,?-unsaturated ketones.disubstituted or trisubstituted furans are important modules in the synthesis of natural products and many drugs which contain furan fragments.Therefore,it is very necessary to develop a simple,atomic economy and non-metal catalyzed method.The molecular iodine is a common oxidant and has a mild Lewis acidity.It plays a catalytic role in both the esterification reaction and the protective group reaction.In organic chemistry experiments,iodine and methyl ketone compounds can undergo iodoform reaction in aqueous sodium hydroxide solution for the detection of acetyl groups.Since iodine has the lowest homogeneity energy,iodine anions are more easily oxidized to simplex or higher valence states.For the iodine-promoted oxidation reaction,there are mainly free radical reactions and in situ substitution reactions,and because iodine seeds are solid,low-toxic,and convenient to operate,therefore,the synthesis of disubstituted or trisubstituted furans using ?,?-unsaturated ketones with iodine is a very effective method.The second part is the synthesis of 2,5-disubstituted or 2,3,5-trisubstituted furan compounds from ?,?-unsaturated ketones.The method for synthesizing a disubstituted or trisubstituted furan compound with an ?,?-unsaturated ketone is similar to the method,except that the amount of dimethyl sulfoxide and the solvent are different,and the furan compound can also be synthesized.It can be seen that the adaptability of iodine molecules to ?,?-unsaturated ketones and ?,?-unsaturated ketones is very good.There are very few reports on the use of a non-metal catalyzed synthesis of polysubstituted furans,and catalytic synthesis of polysubstituted furans by iodine has great significance.