A Practical Solution For Aqueous Reactions Of Water-Insoluble High-Melting-Point Organic Substrates

To date it has been impossible to perform aqueous reactions for very sparinglysoluble high-melting-point (VSSHMP) organic substrates, especially for theVSSHMP substrates with the solubilities at the level of E-10mol/L. An aqueoussystem which entails mechanically stirring a mixture of the substrate, thecorresponding reagent(s), water, a catalytic amount of a liquid ammonium salt Aliquat336and stirring promoter sand have been reported in this dissertation, which is apractical solution to this problem. The power of the approach is demonstrated for fivetypes of reactions: oxidation, reduction of ketones and aldehydes, condensation,hydrolysis and reduction of imines.In the oxidation, a series of VSSHMP pseudosapogenins (mp:72-200oC,solubilities:4.4E-7to5.7E-10mol/L) were oxidated into16-dehydropregenoloneacetate and its analogues using V2O5and H2O2in this aqueous system. Thepseudodiosgenins were all successfully transformed into the corresponding productsin good yields. In these products,16-dehydropregenolone acetate is intermediate forproducing steroid drugs.In the reduction, a series of VSSHMP ketones and aldehydes (mp:111-261oC,solubilities:4.7E-5to2.2E-7mol/L) were reduced using KBH4at room temperatureor60oC in this aqueous system and the crude products were nearly quantitative.Among these products, estradiol and estradiol benzoate are two well-known clinicaldrugs.In the condensation, two sinomenine derivatives were prepared withhydroxylamine hydrogen chloride and phenyl hydrazine hydrogen chloride in thisaqueous system with nearly quantitative yields.In the hydrolysis, a series of VSSHMP esters (mp:95-246oC, solubilities:5.4E-3to1.2E-9mol/L) were hydrolyzed using KOH in this aqueous system in quantitativeyields.In the reduction of imines, a series of imines were reduced using Zn and aqueousNaOH solution in this aqueous system at room temperature in excellent yields.In all these reactions, the catalysts and the water are recyclable and columnchromatography was not resorted. Large amounts of volatile organic solvents could besaved if this method is applied to industry which would be extremely beneficial to theenvironment.