Constructing Heterocyclic Compounds Catalyzed By Fe、Cu And Oxidation Via I₂/TBHP

This thesis mainly discusses two sections:(1) coustructing heterocyclic compounds, including2-pyrroline, tosylthiazolidin-2-ylidene and xanthone catalyzed FeCl3and copper salt;(2) oxidative reaction to construct2,4-disubstituted thiazole, amide bond and directly carbonylation from benzyl group via TBHP oxidation in catalyst-free process.1. Fe, Cu catalyzed synthesis heterocyclic compounds1) Activation aziridine catalyzed by Lewis acid open the three-ring in the nucleophile of alkynyl, and then the intramolecular dipole combined to give pyrroline heterocyclic structure. According to mechanism researches, aziridine ring-open is the key step in the reaction. Also a one-pot reaction efficient synthesize y-amino ketone derivatives was developed.2) Based on the development in the previous chapter, a highly chemo-selective [3+2] dipolar cycloaddition of aziridine with isothiocyanate catalyzed by cheap Lewis acid FeC13and was discovered. The reaction involved a C-N cleavage rather than a C-C cleavage for aziridines and an addition of C=S rather than C=N for isothiocyanate. The racemization experiments indicated the formation of benzyl carbocation from the ring-opening of aziridine to generate a stable1,3-dipolar ion is the key step.3) And then, we developed Cu-catalyst constructing xanthone via oxidation carbonylation of benzyl alcohol and similar F-C acetoxylation and intramolecular nitro substitution reaction.1,10phenanthroline playes an important role in the copper catalyst. The substituent effect of benzyl alcohol is very obvious. We also studied the nitro substitution reaction under the base conditions.2. I2/TBHP oxidation1) On the basic of amidation from benzyl alcohol and formamide catalyzed by iodine/TBHP/base, a new oxidative coupling reaction of benzylamine and formamide combining to amide derivative was developed. The study of reaction mechanism, found that HCl play a key in the process of inhibiting the side reaction.2) Applying I2/TBHP oxidation system,2,4-disubsitituted thiazole hetercycles were synthesized from aromatic aldehyde and ethyl L-cysteine in cascade oxidation reaction. Hydrogenated thiazole was detected by NMR, which demonstrated the cascade oxidation mechanism.3) On the basis of clear understanding of iodine/TBHP oxidation system, and then, we developed a catalyst-free oxidation of benzyl C-H bond to aromatic ketone by TBHP. No any catalyst, only need some excess TBHP oxidant and the rapid decomposition of TBHP under heat.