Strecker-type Reaction Catalyzed By Cinchona Alkaloid-derived Thiourea Catalyst

1. Synthesis of Chiral CatalystsAsymmetric catalysis is the most direct and economic way to obtain optical active compounds. In general, asymmetric catalysis is divided into biological catalysis, metal catalysis and organocatalysis based on different types of catalysts. As the soul of asymmetric catalysis, numerous catalysts have been reported due to the successive development of synthesis technique. In this chapter, several organic catalysts and ligands were synthesized from common chiral source, such as cinchona alkaloid, cyclohexanediamine and (R)-BINOL and some of which were used in subsequent work.2. Asymmetric Strecker reaction catalyzed by thiourea derived from cinchona alkaloidThe asymmetric Strecker-type reactions between azomethine imines synthesized from pyrazolidone and aromatic aldehydes and TMSCN were catalyzed by a cinchona alkaloid-derived thiourea bearing multiple hydrogenbonding donors to afford optically active amino nitriles in good to excellent yields and enantioselectivities. No reported byproducts were detected in most case.3. Investigation on tandem cyclization reaction between thiocyanate and isatinThiocyanate-type compounds shew important applications because of their unique structure. As organic matter, thiocyanates have similar behavior like sulfocyanides which were inorganic substances. Thiocyanate derived from Styrene acrylic cyclopentanone was found to react with isatin in excellent yield and dr in the exisence of TEA. Despite this, asymmetric version of this reaction didn’t give acceptable results.