Application Of Samarium Reagents In Organic Reactions And Study On The Polyesters Synthesis And Their Performance

The dissertation consist of three chapters. The first chapter studies on samarium reagents promoted organic reactions;The second chapter describes organoaluminum complexes catalysed β-butyrolactone(β-BL) ROP reaction;The third chapter studies on polyesters synthesis and their biocompatibility, drug release performance.Chapter one include four parts: The first part introduces the usual types of samarium reagents, and the representative usage in organic synthesis of samarium(II) iodide and metallic samarium is discussed. Generally, activation is needed in the direct use of metallic samarium.The second part studies on the reductive acylation of azo compounds by SmI₂/THF system. Azo compounds without big substituents were conveniently reduced by SmI₂ and successively reacted smoothly with aliphatic acyl chlorides or acid anhydrides to afford corresponding mono-acyl hydrazobenzene under mild and neutral conditions in one pot;while other azo compounds reacted under similar conditions, amides were the terminate products.The third part uses Sm/TiCl₄ instead of SmI₂ based on the above results. We found that Sm/TiCl₄ system can induce the above reaction to afford corresponding amides under mild and neutral conditions.The fourth part deals with preparation of organo sulfur compounds. In general, disulfide was reductive cleavage by Sm/CeCl₃, and then reacted smoothly with acyl halides, anhydrides, alkyl or benzyl halides, α,β-unsaturated esters to afford thioesters, sulfides, β-thioesters respectively under mild and neutral conditions.Chapter two include two parts:In the first part, four aluminum complexes bearing salen ligands were in situ prepared by trimethyl aluminum, methanol, and (R,R)-N,N'-bis(salicylidene)-1,2-di -aminocyclohexane. And these complexes were used as catalysts in the ROP of β-BLto form biodegradable aliphatic polyester PHB. The reaction with II 13 had higher molecular weight(Mn). It seemed that the synthetic results attributed to the higher spatial hindrance around the metal centers.The second part deals with another novel schiff base/aluminum complexes to catalyze P-BL. Six aluminum/Schiff base complex including five new ones, 2,2-dimethyl-l,3-propylenebis(salicylideneimine)methoxyl aluminum were prepared with original synthetic strategies and employed for the ROP of p-BL. In this expriment, the lower of the [Cat.]/[M], the longer of the reaction time, but the Mn varied little, maybe it attribute to the active transesterification under high reaction temperature.Chapter three include three parts, mainly focus on the polyesters synthsis and their performance.Part one deals with synthesis of biodegradable aliphatic poly(butylene succinate-co-cyclic carbonate). Firstly, two P(BS-co-EBTMC) were synthesized through combination of polycondensation and ROP of hydroxyl capped PBS macromers and the prepared 5-ethyl-5-benzyloxymethyl trimethylene carbonate (EBTMC), Ti(O-/Pr)4 was employed as catalyst;Based on it, P(BS-co-EBTMC-co-EHTMC), which bearing hydroxyl pendant funcional group, was synthesized through Pd/C catalyzed hydrogenation;Thirdly, Epristeride(SK&F 105657), a potent uncompetitive inhibitor of 5a-dihydrotestosterone was grafted to the pendent hydroxyl of hydrogenized P(BS-co-EBTMC) by EDC.Part two was in vitro cell biocompatibility assay of the polyesters P(BS-co-CC) and novel multi-arm PLLA series. In this assay, we found that the NIH 3T3 attachment occurred in 3h cell/material interaction. Cell cultured in each group maintained their character morphology after cultured 5h. Then, MTT assay showed that polyesters of 5-arm PLLA X, 3-arm PLLA G and P(BS-co-TMC) has better biocompatibility as TCPS.Part three focused on the Epristeride loaded microspheres based on the newpolyester P(BS-co-CC) and multi-arm PLLA series, which were fabricated using oil-water emulsification extraction/evaporation technique. The drug release experiment was investigated by immersing the microspheres under pH= 7.4, pH= 10.0, pH= 2.2, pH=2.2 (Protein K) buffer. The results showed that in pH= 7.4 buffer, P(BS-co-TMC) showed nearly constant release profile during day 2-8. The addition of Protein K in the buffer can accelerate drug release suggest a release maybe controlled by the degradation of the polymer.