The Research And Application Of Ultrasound Irradiation, Ionic Liquid And Solvent-free Synthetic Techniques In Organic Synthesis

The thesis mainly focused on organic reactions under ultrasound irradiation, ionic liquids and solvent-free conditions, it's composed of following three parts: In the first part, we investigated organic reactions under ultrasound irradiation: base-promoted one-pot syntheses of β-indolylketones and Biginelli-like scaffold compounds, alkynylation of ketone with ethynylbenzene, syntheses of ferrocenyl substituted α, β-unsaturated ketones and the reactions of them with deoxybenzoin and dibenzyl ketone. In the research we found that, compared with conventional stirring method, organic reactions utilizing ultrasound irradiation could be carried out with milder reaction conditions, easily-handled manipulation, accelerated reaction speed, shortened reaction time and enhanced yield. The promising method with a broad application value is expected to replace conventional method in organic reactions in the near future. Moreover, we discovered the first base-promoted method (conventional methods were carried out under Lewis acid or Bronsted acid conditions) for the syntheses of β-indolylketones and Biginelli-like scaffold compounds, the method will certainly provide us with a novel method and broaden our concepts. Furthermore, we prepared a series of ferrocenyl substituted 1, 5-diketones and cyclohexenones compounds via the reactions of ferrocenyl substituted α, β-unsaturated ketones with deoxybenzoin and dibenzyl ketone, and further discussed the influence of reaction time, temperature and the basicity of different promoters on the reactions. In the second part, we studied organic reactions in the presence of environmentally friendly ionic liquids: cyanosilylation of aldehydes with TMSCN, one-pot syntheses of O-acetylcyanohydrins, and Mukaiyama aldol reaction. It's interesting to find that imidazolium-based ionic liquids could efficiently promote the reaction of aldehydes with TMSCN and one-pot syntheses of O-acetylcyanohydrins with high yields without the addition of any Lewis acids or bases. In the meantime, the ionic liquids could be recovered and recycled for subsequent runs without or with a little loss of activity. However, both the two reactions could not take place in conventional organic solvents without the addition of Lewis acid. Furthermore, we synthesized a more polar ionic liquid (solid in r.t.), and the combination of it with usual room temperature ionic liquid could form a new type of more polar ionic liquid which could promote Mukaiyama aldol reaction effectively. Recycling of the ionic liquid also has been studied. In the last part, we researched organic reactions under solvent-free conditions: reactions of ferrocenyl substituted α, β-unsaturated ketones with diethyl malonate, deoxybenzoin and dibenzyl ketone, DBU-catalyzed Mukaiyama aldol and Mukaiyama-Michael reactions, L-proline salt-catalyzed cyanosilylation of ketone with TMSCN, and Lewis acid InI3 catalyzed one-pot synthesis of α-aminonitrile in water. The solvent-free synthetic technique and above ionic liquid synthetic technique will not only avoid the use of conventional poisonous and volatile organic solvents leading to environmentally friendly "green chemistry", but also save the expenditure and find a broad application in organic synthesis. In the research, we coupled both microwave irradiation and solvent-free synthetic techniques, and applied it to the reaction of ferrocenyl substituted α, β-unsaturated ketones with diethyl malonate with short reaction time, fast speed and high yields. Next, we found that the reactions of ferrocenyl substituted α, β-unsaturated ketones with deoxybenzoin and dibenzyl ketone could proceed efficiently under solvent-free conditions simply by grinding, and further discussed the influence of reaction time, temperature and the basicity of different promoters on the reactions. Third, in our discussion of organocatalyst DBU-catalyzed Mukaiyama aldol and Mukaiyama-Michael reactions, we found that Mukaiyama aldol reaction could proceed more efficiently under solvent-free conditions than in conventional organic solvents. Forth, our group is the second group who applied L-proline salt to organic reaction after Yamaguchi, and found that L-proline salt could highly promote the cyanation of ketone (including steric hindered ketone) with high yields and easily-handled manipulation. Moreover, we also discussed the reaction in the presence of the salt of α-amino acids and α-hydroxy acids. Finally, we explored water-stable Lewis acid InI3 promoted one-potsynthesis of a-aminonitrile via three-component condensation of aldehyde, amine and TMSCN in water, the approach was demonstrated to be efficient and environmentally-friendly.