Decarboxylation Dipolar Reversal Strategy For The Synthesis Of Cyclic Alcohols And Cyclic Diamine Compounds

Carbon anions are a class of very important reaction intermediates that react with electrophiles to produce various compounds with different backbones,playing an important role in organic chemistry.The Chemistry has attracted much attention in organic chemistry communityUmpolung of polarity Dipole reversal is an important strategy in organic synthesis.By reversal of polarity,electrophilicity and nucleophilicity can be changed with each other,resulting in many new reactivities.The Umpolung strategy has contributed a lot to the progress of organic chemistry.The research in this thesis mainly includes the following two parts:(1)Decarboxylative Umpolung of ?,?-unsaturated enals for nucleophilic addition at the ? position to electrophiles.A variety of ?,?-unsaturated enals are converted to delocalized carbanions via decarboxylation of the Schiff bases formed between ?,?-unsaturated enals and 2,2-diphenylglycine.The in situ generated carbanions undergo immediate addition at the ?-position to an intramolecular aldehyde group to give various cyclized products in 54-93% yields with up to >20:1 trans/cis selectivity.(2)Decarboxylative Umpolung synthesis of cyclic vicinal diamines from dials.By using the decarboxylative Umpolung strategy with 2,2-diphenylglycine,the aldehyde groups of aldehyde-imines are efficiently reversed into delocalized nucleophilic ?-amino carboanions,followed by intramolecular addition to the imine group to form a variety of cyclic vicinal diamines in good yield with excellent diastereoselectivities(trans/cis > 20:1).