| This thesis includes two sections:1,Study on reduction of quaternary ammonium salts.Aromatic amines are one of the most commonly used functional groups and have a strong localization effect in organic synthesis.Sometimes,the elimination of amines is necessary.For aromatic primary amines,they can be transformed into diazonium salts and then reduced.However,for aromatic secondary amines and tertiary amines,there are not so many methods for their eliminations.To eliminate them,a mild and practical method is the conversion of them into quaternary ammonium salts followed by reductive elimination.In our studies,the reductive elimination of quaternary ammonium salts was carried out with NaH as a reductant and palladium chloride as a catalyst.This new method features mild reaction conditions,easily available reagent and catalyst,and convenient operations.This C-N bond cleavage mode enlarges the use of dimethylamines by providing a way to transform functional groups such as dimethylamines,which are common but have low reactivity,into useful synthetic intermediates.2,Study on selective debromination of tribromo compounds.Tribromomethyl group is present in some biologically active natural compounds,and also acts as intermediates in the synthesis of many useful compounds.In our method,bromoform was used as a tribromomethyl source.An 1,4-addition reaction of bromoform and unsaturated ketones at low temperature was carried out with NaHMDS as base to obtain a tribromomethyl group-containing compounds.The tribromomethyl compounds could be debrominated in different solvents under the action of CaH2 and PdCl2 to obtain different debromination products.The reaction can introduce a-CBr2H or-CH3 on a wide range of substrates with simple operation. |
