Study On The Synthesis Of Benzofurans Derived β-amino Acid Esters

Benzofuran compounds is an important heterocyclic compounds, presenting in awide variety of natural products and synthetic compounds. Owing to their biophysicaland pharmacological activities, the benzofurans and their derivatives have attracted considerable attention in the fields of medical intermediates and other fields.The paper mainly studied the synthesis and the structure of benzofurans derived β-amino acid esters.(1): Five benzofurans derived β-amino acid esters5a~5e.(2): Three benzofurans derived β-amino ketone14a~14c.(3): Ten diethyl3-((S)-1,1-dimethylethylsulfinamido)-benzofuran-2,2(3H)-dicarboxylate compounds9a~9j and Four diethyl3-((R)-1,1-dimethylethylsulfinamido)-benzofuran-2,2(3H)-dicarboxylate compounds10b~10d,10i were prepared.The structure of these new compounds was determined by1H NMR、13C NMR and HRMS techniques. The crystal structure of Benzofuran compounds9b were conducted by diffraction test.(1): imines has been shown to be an important intermediate in recent years. Fivenew imines3a~3e were synthesized by using salicylaldehydes1and p-Toluenesulmide2. Twelve new (E)-N-(2-hydroxybenzylidene)-2-methylpropane-2-sulfinamide derivatives7a~7k were synthesized by using salicylaldehydes1and chiral tert-butanesulfinamide2via microwave irradiation techniques in moderate to good yields.(2): Using Methyl Benzenesulfonimide3and diethyl bromomalonate4as raw materials, the benzofurans derived β-amino acid esters5a~5e were prepared. Using MethylBenzenesulfonimide3and Bromoacetophenone13as raw materials, the benzofurans derivedβ-amino ketone14a~14c were prepared. Using N-tert-butanesulfinyl imines7anddiethyl bromomalonate4as raw materials, the compounds diethyl3-((R)-1,1-dimethylethylsulfinamido)-benzofuran-2,2(3H)-dicarboxylate compounds8a~8j were prepared.(3): The single diastereomer9a~9b,10b~10c,10i were obtained by the separatingmeans of Silica gel column and recrystallization. Using the method of solution evaporation, the single diastereomers were monocrystalline cultured. The monocrystal of9bwas obtained and was chiral structure of S-configuration by diffraction testing. So, weconfirmedthat the single diastereomers9a~9b were S-configuration.(4) Using diethyl3-((R)-1,1-dimethylethylsulfinamido)-(S)-benzofuran-2,2(3H)-dicarboxylate9a and acetic anhydride11as raw materials, the compounds diethyl3-acetamidobenzofuran-2,2(3H)-dicarboxylate12a were prepared. Using salicylaldehydes1，tert -butanesulfinamide6，diethyl bromomalonate4and acetic anhydride11as raw materials, the compounds diethyl3-acetamidobenzofuran-2,2(3H)-dicarboxylate12o were prepared. And its ee value was determined. The ee value was95%.