References:

Akiyama, T.; Matsuda, K.; Fuchibe, K. Synlett, 2005, 2, 322-324.

Mannich-type reactions are useful for the preparation of beta-amino carbonyl compounds, which are important for the synthesis of biologically active nitrogen-containing compounds. Akiyama et al. describes a Mannich-type reaction of cyclohexanone with an aldimine derived from benzaldehyde and p-anisidine, using variety of acids and sodium dodecylsulfate (abbreviated as SDS) as reagents and water as a solvent at room temperature for 12-24 hours, as shown by the figure below.

This Mannich-type reaction is stereoselective based on the solvent system used and also on the structure of the major organic reagents. With water and SDS, the reaction exhibits high anti-selectivity, whereas when an aqueous organic or non-aqueous organic solvent is used, the reaction showed low stereoselectivity. Additionally, yield was correlated with stereoselectivity. The effects of solvent and structure are summarized in the tables and figure below. The researchers also reported that HCl used as the catalyst gave yield to high anti-selectivity.

Table 2: Effect of Solvent System



Guo, Q.-X.; Hua, L.; Guo, C.; Luo, S.-W.; Gu, Y.; Gong, L.-Z. J. Am. Chem. Soc., 2007, 129, 3790-3791.
Guo et al. cited this article in the explanation of the mechanistic proposal for the Brønsted acid-catalyzed Mannich reaction, indicating that a carbonyl compound possessing alpha-hydrogens will enolize in acid, and the formed enol will attack the protonated aldimine generated in situ from an aldehyde and a primary amine in the presence of the acid.

He, T.; Li, K.; Wu, M.-Y.; Feng, X.-W.; Wang, N.; Wang, H.-Y.; Li, C.; Yu, X.-Q. Journal of Molecular Catalysis B: Enzymatic, 2010, 67, 189-194.
He et al. cited this article to show the rarity of one-pot procedures using unmodified aldehydes or ketones in water reported in literature.

Mukhopadhyay, C.; Datta, A.; Butcher, R. Tetrahedron Lett., 2009, 50, 4246-4250.
Mukhopadhyay et al. cited this article because of the inclusion of three-component Mannich reactions of cyclohexanone.

Works Cited

"2,4-Dinitrobenzenesulfonyl Chloride." Chemical Book---Chemical Search Engine. Web. 02 Apr. 2011. http://www.chemicalbook.com/ChemicalProductProperty_EN_CB0472238.htm

"An Introduction to Mass Spectrometry." (1997). Chester, PA: Van Bramer, Scott E. PDF. 02 Apr. 2011. http://science.widener.edu/svb/massspec/massspec.pdf

"Flash Chromatography." Scientific Adsorbents Inc. Web. 02 Apr. 2011. http://www.saiadsorbents.com/flash.htm.