Anirban Mondal and Kartick C. Bhowmick* Pages 165 - 170 ( 6 )
Background: A cheap and commercially available organocatalyst, (1R, 2R)-(+)-1, 2- diammonium cyclohexane-L-tartrate 1 was applied in direct aldol reaction in water. The organocatalyst 1 afforded aldol products from cyclohexanone and substituted aromatic aldehydes with high yield (up to 90%) and good stereoselectivity (up to 99% ee and up to 11.5:1 dr) in large volume of water (10 ml).
Methods and Results: The same aldol reaction when carried out in th presence of more expensive organocatalyst e.g. (1R, 2R)-(+)-1,2-diaminocyclohexane and 1,6-hexanediaoic acid as acid additive furnished the aldol products with only 20% yield, 2:1 anti/syn ratio and 92% ee.
Conclusion: In summary, we have applied a reasonably cheap and commercially available organocatalyst 1 for highly enantioselective direct aldol reaction in water at room temperature.
1, 2-diaminocyclohexane-L-tartrate, 1, 6-hexanediaoic acid asymmetric aldol reaction, cyclohexanone, organocatalysis, water.
Division of Organic Synthesis, Department of Chemistry, Visva-Bharati (A Central University), Santiniketan-731 235, West Bengal, Division of Organic Synthesis, Department of Chemistry, Visva-Bharati (A Central University), Santiniketan-731 235, West Bengal