Studies On Methodology Of Stereoselective Organic Syntheses

This thesis consists of two parts:Part one deals with the synthesis of pyrethroin. Pyrethroin is synthesized by cyclization and elemination of 4,6,6,6-tetrachloro-3,3-dimethyl hexanoates. The factors that governed the formation of the desired products are studied. Both Chemical yield and syn/anti is increased, and the syn/anti is controlled by the solvent used in the cyclozation of 4,6,6,6-tetrachloro-3,3-dimethyl hexanoates.Emphasis is put on the second part. Part two mainly deals with alkylation of imine with diethyl zinc mediated by amino alcohols and allylation of imines.In alkylation of imines, natural products Cinchonidine and Quinidine were used as catalysts in the addition of diethyl zinc to phosphinoylimine and better results were obtained both in chemical yields and enantioselectivity. What's more, catalytic amount of cinchonidine was realized. In addition, three new chiral amino alcohols were designed and synthesized successfully from the commercial available natural products-amino acids. The application of N-a-ferroceny-methyl-B-amino alcohol (21) to the addition of diethyl zinc was demonstrated. The amino alcohol (21) has some chemical and stereoselective effect on the reaction.In allylation of imines, catalytic effect of Cinchonidine, Quinidine, Cyclopenta-dienyl-[(4R, trans)-2,2-dimethyl-a, a, a', a' -tetraphenyl-1,3 -dioxolane-4,5 -dimethanola-to-O,O']titanium chloride (Ti(IV) complex 25), BINOLTiCl2 and Pd complex 27 was examined. In the five examined ligands, the Pd complex 27 was proven to have some effects on the allylation of imines with allyltributyltin, though the chemical yield and ee is not quite satistied.