Studies on the Development of New Generation Method of Nitrogene Centered Radicals and their Application to Intermolecular Cycloaddition Reaction

点击翻译按钮获取中文摘要

The present research is development of efficient generation method of various aza-homoallyl radical (2-alkenylated amidyl radicals) species using iodoaziridine derivatives and their application to intermolecular radical [3+2] cycloaddition reaction. The results in 2004 are as follows.1.Synthesis of optically active octahydroindole derivatives through asymmetric radical [3+2] cycloadditionIn last year, I reported asymmetric radical [3+2] cycloaddition using optically active bicyclic iodoaziridine. The product of the present reaction should be useful synthetic intermediate of various natural octahydroindole alkaloids. However, radical reaction is not generally useful for natural product synthesis, because remarkable decrease in the chemical yield is often observed by the scale up of the reaction. On the other hand, I found that the present reaction can scale up to 5 mmol without the decrease in the chemical yield and the stereoselectivity2.Radical cascade reaction of iodomethylcyclopropane derivative with dienes and enynesIn relation to the present reaction using iodoalkylated three-membered ring compound, I have reported iodine atom transfer radical [3+2] cycloaddition reaction using iodomethylcyclopropane having two electron-with drawing group on the ring. That is, in the present of triethylborane, the iodomethylcyclopropane efficiently generates allylated active methine radical which gives cyclopentane derivatives with good yields and stereoselectivities through the iodine atom transfer cycloaddition with various alkenes. In this year, I invesigated radical cascade reaction with dines and enynes. I found that the reaction of iodomethylcyclopropane with 1,4-dienes and 1,4-enynes gives bicycle [3.3.0] octane derivatives in good yields through [3+2] cycloaddition and subsequent 5-exo-cyclization.