Chemo-and Site-selective Fischer Esterification Catalyzed By B（C₆F₅）₃

Ester compounds are widely used in the fields of medicine,food,chemicals and materials.Although the new catalytic synthetic methods developed in recent years have made great progress in the construction of ester bonds,the problem of racemization in the esterification of chiral amino acids and lack of highly selective monoesterification of polyols have not yet been achieved.This dissertation describes two parts of the research work.In the first part,an esterification method using tris（pentafluorophenyl）borane[B（C₆F₅）₃]as a catalyst and methanol as a nucleophile and reaction solvent was developed to synthesize ester compounds from carboxylic acids and amino acids.In the second part,the selective monoesterification of organic acids and polyols with tris（pentafluorophenyl）borane[B（C₆F₅）₃]as a catalyst was studied.The main content of work is as follows:（1）Fischer esterification of carboxylic acids and amino acids catalyzed by B（C₆F₅）₃In this part,1-methyl-3-indoleacetic acid was used as the raw material,and was directly dehydrated and esterified with methanol under the catalysis of B（C₆F₅）₃ to form the target product.Among them,the solvent has a greater impact on the reaction,and finally methanol was selected as both the nucleophile and the reaction solvent.Subsequently,we tried to esterify20 natural amino acids with methanol.Compared with the literature work,we successfully obtained non-racemic amino acid esterification products.Compared with the traditional esterification method,this method is a metal free and no strong acid involved.It is an environmentally friendly and efficient esterification method.This method has a very wide range of substrates scope,including 28 carboxylic acid substrates and 24 amino acid substrates,and the yield is good to excellent.（2）Highly selective monoesterification of organic acids and polyols catalyzed by B（C₆F₅）₃Monoglycerides are a class of bio-derivatized products that are widely used in food additives,cosmetic ingredients,pharmaceutical compounds,plasticizers and non-ionic surfactants.In this part,based on the previous work,we have developed a highly selective monoesterification reaction of polyols.Under the catalysis of B（C₆F₅）₃,various organic acids and polyols are directly esterified in one step to obtain the target product of monoesterification.Compared with the traditional monoesterification method of polyols,this esterification shows excellent chemo-and site-selective monoesterification of various polyols without any protection step,including bio-derived molecule glycerol.This method expanded 17 substrates,of which 8 were monoglyceride substrates,and the yield was good.