Talk:Proline-catalyzed aldol reactions

message: andOrganocatalysis
User:Zghajos From Wikipedia, the free encyclopedia Jump to: navigation, search Remarks to the Wikipedia Organocatalytic aldol reactions
Zoltan G. Hajos zghajos(AT)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. doi:10.1039/C39850000441
e. Movassaghi, M.; Jacobsen, E. N., Science, 2002, 298, 1904-1905. doi:10.1126/science.1076547
f. List, B, Tetrahedron 2002, 58, 5573-5590 doi:10.1016/S0040-4020(02)00516-1 references 12 doi:10.1021/jo00925a003 and 13 doi:10.1002/anie.197104961
* Thanks Zoltan for your comments, I have incorporated some of it in the article itself but feel free to make edits yourself. I have been trying to find the German patent (nowadays I would expecting these patents to be freely available on the internet) but no luck. Help would be appreciated V8rik (talk) 17:45, 17 January 2008 (UTC)

message: With respect to Dr. Hajos, I don't believe it's appropriate for someone to write about their own research here.  The discussion of mechanism in this article seems biased towards the originally proposed mechanism.  Statements like "It is interesting and surprising that Eder, Sauer and Wiechert have not attempted to explain the reaction mechanism" are unprofessional and unnecessary.  I think virtually everyone agrees that the List-Houk mechanism is the right one these days, but the article is now so convoluted it's impossible for a person unfamiliar with this work to tell.  Also, why is there discussion of other aldol reactions?  For example, the discussion of the nitroso aldol reaction seems out of place.  I think we need to do some pruning here, and this should be done by someone who's not involved with the chemistry in any way.  But I'll wait to see what others think before taking any action.  Eugene Kwan (talk) 15:32, 9 April 2011 (UTC)
thread_title:  Neutrality