Sienkiewicz, "Studies on aldol reactions of nortropinone derivatives in solution and on solid phase," Letters in Organic Chemistry, vol.
Houk, "Computational investigations ofthe stereoselectivities of proline-related catalysts for aldol reactions," Journal of Molecular Catalysis A: Chemical, vol.
The organocatalytic aldol reaction  is one of the most powerful methods for forming C-C bonds in a highly stereocontrolled manner.
Chiral lithium amide promoted aldol reaction of tropinone (1, 8-methyl-8-azabicyclo[3.2.1]octan-3-one) has been used by us [13, 14] and others [15, 16] as a diastereoselective and enantioselective key step in several syntheses of tropane derivatives, mostly natural tropane alkaloids.
The spontaneous deuteration is faster than aldol reaction, the rate of which depends also on reactivity of the aldehyde used, indicating that the rate limiting step of the whole process is not the enolization.
Previously , we found the B3LYP/6-31G(d) [41, 42] method as a good tool for investigating the stereoselectivity in the aldol reaction of the bicyclic amino ketones in the presence of water.
At first glance, the reaction parameters obtained from our computational approach, at 6-31g(d) level (but also at 6-311++g(3d,3p) vide infra), calculated along the lines used for aldol reaction of acetone by Zhang and Houk , that is, the reaction of tropinone and granatanone enols with benzaldehyde, totally disagreed with experiment.
Brindle, "The direct catalytic asymmetric aldol reaction," Chemical Society Reviews, vol.
Beletskaya, "Organocatalysis of asymmetric aldol reaction. Catalysts and reagents," Russian Chemical Reviews, vol.
The catalytic activities of pyridinium salts were also investigated starting with the aldol reaction of acetone with 4-nitrobenzaldehyde.
General Procedure for Aldol Reaction with Catalysts6, 7 and 8To a stirring mixture of acetone (10.0 mmol) and water (3 mL), Catalyst 6, 7 or 8 (10 mol%) was added.
Using these proline amides and pyridinium salts as catalysts in aldol reaction is also important from the viewpoint of green chemistry, because of using environmentally friendly solvent water.