The Study On Indium Chloride Promoted Reduction Of Alkynes And Carbonyl Compounds

As a Lewis acid, Indium chloride is of excellent qualities such as nontoxicityand compatibility with water and air. It can promote many kinds of organic reactions.Recently, application of Indium chloride in organic reactions has attracted more andmore chemists' interest. In this thesis, application of Indium chloride in the reductionof alkynes and carbonyl compounds was studied. This thesis consists of foursections.In section 1, reduction of alkynylphosphates in InCl₃-NaBH₄-MeCN systemwas investigated, in which a series of (E)-arylvinylphosphates were obtained in highyield and selectivity. First, the conditions of the reaction were optimized withphenylalkynylphosphate as the substrate. Under the optimized conditions the effectof the different substitutents on the reaction were investigated. It was found thatbetter yield and selectivity were obtained when there was conjugate structure in thesubstrate. For aromatic substrates, when the hydrogen atom of benzene ring wassubstituted by an electron-donating group, the yield and stereoselcetivity decreasedslightly, while hydrogen atom of benzene ring was substituted by anelectron-withdrawing group the yield and selectivity were rather high. Finally,possible mechanism was proposed. Based on the reaserch of this part, we developeda convenient and effective way to synthesize (E)-arylvinylphosphates.In section 2, reduction of alkynylsilanes in InCl₃-NaBH₄-THF system wasinvestigated, in which a series of (E)-arylvinylsilanes were obtained in high yieldand selectivity. First, the conditions of the reaction were optimized withphenylalkynylsilane as the substrate. Under the optimized conditions the effect of thedifferent substitutents on the reaction were investigated. It was found that electronic effect was similar with the reduction of alkynylphosphates. On the other hand, therewere two defferences between reductions of alkynylphosphates and alkynylsilanes:(1) solvent; (2) In reductions of alkynylsilanes in InCl₃-NaBH₄-THF systemover-reduced products were detected, however, they were not dectected in reductionsof alkynylphosphates. The possible reason was discussed according to themechanism. In this section, we afforded a convenient and effective way to synthesize(E)-arylvinylsilanes.In section 3, pinacol coupling reactions of aldehydes and ketones in aqueousmedia with InCl₃/Al reagent were studied systemically, in which 1, 2-diols wereobtained in moderate to good yield. First, the conditions of the reaction wereoptimized with benzophenone as the substrate. It was found that higher temperaturewas in faver of the pinacol coupling of benzophenone in this system. Under theoptimized conditions the pinacol coupling reactions of the benzophenones,benzaldehydes and acetophenones with different substitutents were investigatedsystemically, which showed that their reaction activity was weakened in sequence.The substrates bearing electron-withdrawing groups had higher activity than thosebearing electron-donating groups. Because of steric hindrance the correspondingreduction products were obtained as main products when the substrates bear thesubstituents ortho to ketones. Furthermore, InCl₃/Al mediated intramolecule pinacolreactions of 1, 5-dicarbonyl compounds were investigated. In this section, weafforded a convenient and effective way to synthesize 1, 2-diols.In section 4, InCl₃/Al mediated reductions of anthrones (9, 10-anthraquinones)were investigated. Under the optimized conditions in section 3, anthrones werereduced to anthrances and 9, 10-dihydroanthrances instead of the pinacol products orthe corresponding alcohols. The reduced products of anthrones could be controlledto anthrances by optimizing the reaction conditions. Furthermore, InCl₃/Al mediated reductions of anthrones bearing different substitutents were investigated. On theother hand, InCl₃/Al mediated reductions of 9, 10-anthraquinones were studied. Inthis section, we afforded a convenient and effective way to synthesize anthrancesfrom anthrones.In addition, InCl₃-promoted organic reactions were generally reviewed.