User:Zghajos
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Remarks to the Wikipedia Organocatalytic aldol reactions
Zoltan G. Hajos zghajos@t-online.hu
The reaction scheme (a) as shown in the Wikipedia Organocatalytic aldol reactions page has only been described in the Hajos, Parrish Patent (b) and the Hajos, Parrish paper (c).
Since Hajos and Parrish worked at ambient temperature using a catalytic amount (3% molar equiv.) of (S)-(-)-proline they could isolate the optically active intermediate bicyclic ketols a prerequisite of elucidating the reaction mechanism. This was most likely the reason for Professor Claude Agami to call the reaction the Hajos-Parrish reaction in his paper in J.Chem.Soc., Chemical Commun., 1985, 441-442 (d).
The Hajos, Parrish Patent (b) also described the Asymmetric synthesis utilizing (S)-(-)-proline even in the absence of added solvent.
The last few lines of the Hajos, Parrish 1974 paper read: "We believe our results may be considered an example of a simplified model of a biological system in which (S)-(-)-proline plays the role of an enzyme." This has been referred in a publication by Mohammad Movassaghi and Eric N. Jacobsen of the Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA: The Simplest "Enzyme" Science, 6 December 2002, Vol. 298, 1904-1905 (e).
The above is also described in the Benjamin List Tetrahedron report number 613 in 2002 (f). This Tetrahedron report shows that the Schering group executed the reaction under non biological conditions using (S)-Proline (47 mol%), 1N perchloric acid, in acetonitrile at 80 degrees C. Hence, they could not isolate the Hajos, Parrish intermediate bicyclic ketols. The original 1985 naming of the reaction by Claude Agami (d) has been expanded in this 2002 paper (f) by adding three more names of the Schering group.
References to the Zoltan G. Hajos Remarks. a.http://upload.wikimedia.org/wikipedia/commons/d/de/Organocatalytic1.gif]
b. Hajos, Z, G.; Parrish, D. R. Asymmetric Synthesis of Optically Active Polycyclic Organic Compunds. German Patent DE 2102623, July 29, 1971.
c. Hajos, Z. G.; Parrish, D. R. J. Org. Chem. 1974,39,1615.
d. Agami, C.; Levisalles, J.; Puchot, C. J. Chem. Soc., Chem. Commun. 1985, 8, 441-442.
e. Movassaghi, M.; Jacobsen, E. N., Science, 2002, 298, 1904-1905.
f. List, B, Tetrahedron 2002, 58, 5573-5590 references 12 and 13.
