Novel MCR 3 reaction leading to an interesting zwitterionic structure: Parallel synthesis of pyridinium-pyrazol-3-olate inner salts

ORGN 791

László Ürge1, László Varga2, Tamás Nagy2, György Dormán3, Ferenc Kálmán3, and Ferenc Darvas3. (1) ComGenex, Inc, 33-34 Bem rkp, H-1027, Budapest, Hungary, (2) Bem rkp. 33-34, ComGenex Inc, H-1027 Budapest, Hungary, (3) 33-34 Bem rkp, ComGenex, Inc, H-1027, Budapest, Hungary
We have realized several syntheses of compound libraries based on pyrazolones that are highly variable and easily preparable synthetic building blocks.  Recently, we have investigated the formation of a C-C bond on C-4 atom of the heterocyclic core, employing various alkylating agents including dichloro-maleimides in the presence of different bases.  Surprisingly, in the presence of pyridine unusual highly colored crystalline products were obtained.

The structures were confirmed by 1H- and 13C-NMR, HR MS and X-ray analysis indicating that the pyridine ring was covalently attached to the molecule (forming 1:1:1 adduct) as a zwitter ionic inner salts.

Based on the developed procedure a medium-sized library was successfully prepared with high purity. The isolated yield varied depending on the substituent pattern (18- 91 %) giving an average of 72 %.  

In the presentation the synthetic conditions of the novel MCR3, and the properties of the characterized zwitter ionic inner salts are discussed.

 

Combinatorial, Parallel, and Solid-Phase Chemistry
1:00 PM-5:00 PM, Thursday, August 26, 2004 Pennsylvania Convention Center -- 202B, Oral

Division of Organic Chemistry

The 228th ACS National Meeting, in Philadelphia, PA, August 22-26, 2004