Palladium Catalyzed N-Arylation Reaction Of Aryl Chlorides And Synthesis And Application Of Phosphorus Ligands

The transition-metal-catalyzed cross-coupling reactions are simple, efficient, and versatile routes to the formation of carbon-carbon and carbon-nitrogen bonds, which represents the key step in a wide range of preparative organic processes. Recently many chemists are searching for better catalysts, more convenient reaction conditions and an insight of the reaction mechanisms, and are using these cross-coupling reactions for the synthesis of interesting or promising compounds. This paper mainly studies palladium-catalyzed C-N cross coupling reaction of aryl chlorides and amino acids.(1) The tube is charged with L-valine, Pd2(dba)3, Johnphos (2-(di-tert-butylphosphino)biphenyl) and sodium tert-butoxide (NaOtBu). The septum is again placed on the flask, and the flask is purged with argon for 5 min. Chlorinated aromatic and 1,4-dioxane is added and stirring is started. The mixture is placed in an oil bath that is heated to 60℃,70℃,80℃and 100℃. The product is extracted with CH2Cl2. The CH2Cl2 solution was dried and concentrated to give a brown solid which was purified by column chromatography. There is at 70 to 80 degrees to obtain the good yield;(2) The tube is charged with L-valine, L-Isoleucine or L-leucine, Pd2(dba)3, Johnphos and sodium tert-butoxide (NaOtBu). The septum is again placed on the flask, and the flask is purged with argon for 5 min. The mixture is placed in an oil bath that is heated to 80℃for 2 h in the same reaction system. We obtain the best yield: 85%. We obtain the very good yield without o-chlorotoluene. There is the reason which is stereo- hindrance effect;In addition, we also did some other work:(1) Chiral 1,5-dinaphthol was protected with MOM, otho-lithiumized, and then formylated to give products with one formyl group. The product was hydrolyzed to recover the two hydroxyl groups;(2) Thiamphenicol was hydrolyzed to obtain 2-amino-1-(4-(methylsulfonyl) phenyl)propane-1,3-diol.And then 2-amino-1-(4-(methylsulfonyl)phenyl)propane-1,3–diol was methylated to obtain 2-(dimethylamino)-1-(4-(methylsulfonyl)phenyl) propane-1,3-diol;...