Study On The Reactions Of Aromatic Isothiocyanates And Organozinc Halide Reagents

Isothiocyanates are important intermediates in organic synthesis. They can participate in varieties of organic reactions to produce various types of sulfur, nitrogen, oxygen heterocyclic compounds. In particular, they are mainly used in the synthesis of pesticide, medicine and dyes. Recently the preparation of isothiocyanates and their application arouse widespread concern. In addition, the organozinc reagents have good capacity carrying functional groups, due to their low reactivities, high selectivity and stereoselectivity of chemical reactions, it is ideal reagents to build multifunctional complex compounds. Herein, the reactions of organozinc reagents and aromatic isothiocyanates were firstly investigated.These thesis includes three chapters.Chapter one: The application of aromatic isothiocyanates in organic synthesis.In this chapter, a brief introduction of the development of isothiocyanates in organic synthesis was given. Then we reviewed in detail on the preparation and reaction of isothiocyanates, which were of the most importance both on application and theory.Chapter two: Reactions of aromatic isothiocyanates and organozinc halide reagents.The reactions of aromatic isothiocyanates and organozinc halide reagents was investigated in this chapter. Our study shows aromatic isothiocyanates can react with allyl zinc bromide or benzyl zinc bromide to give secondary amines or thioacid amides in THF without catalyst. The method has following advatantages: catalyst free conditions, simple operation, mild conditions, less byproduct, easy isolation, high yield, which is probably to be a feasible method to synthesize secondary amines and thioacid amides. Chapter three: New methods for synthesis of p-fluorobenzaldehyde.A new method for preparation of p-fluorobenzaldehyde was developed in this ch -apter. P-fluorobenzoic acid was converted to Winreb amide under P[NCH3(OCH3)]3, which then reacted with Vitride to give p-fluorobenzaldehyde. The synthetic method has following advatantages: simple operation, mild conditions, less byproduct, easy isolation and high yield, which is probably to be a feasible method to synthesize p-fluorobenzaldehyde.