Asymmetric Aldol Reaction in Brine

T Miura et al (SYNLETT, 2011, (3), 410) describe an organocatalysed asymmetric aldol reaction which is carried out in brine solution.  The typical procedure describes mixing the aldehyde with the ketone in brine in the presence of catalytic quantities of TFA and the organocatalyst and stirring the mixture at room temperature for 36h.  The products were generally isolated by extraction into organic solvent, but it is interesting to consider how, subject to the substrates and later chemistry, the process may be rendered more environmentally friendly, perhaps by more direct isolation or telescoping.

The paper contains 11 example with isolated yields up to 80% and ee’s generally above 90%.  Of the 11 examples, 9 used cyclohexanone so it will perhaps remain to be seen how broad the scope truly is.