Functionalized 4-Aminoquinolines by Rearrangement of Pyrazole N-Heterocyclic Carbenes
作者:Andreas Schmidt、Niels Münster、Andrij Dreger
DOI:10.1002/anie.200905436
日期:2010.4.1
Thermal decarboxylation of 1‐phenylpyrazolium‐3‐carboxylates from the mesomeric betaine class of substances leads to pyrazole‐N‐heterocyclic carbenes, which immediately rearrange to multiply substituted 4‐aminoquinolines (see scheme). These species are of interest for the synthesis of heterocycles and pharmacologically active compounds.
New Pyrazolium-carboxylates as Structural Analogues of the Pseudo-Cross-Conjugated Betainic Alkaloid Nigellicine
作者:Andreas Schmidt、Tobias Habeck、Markus Karl Kindermann、Martin Nieger
DOI:10.1021/jo0344337
日期:2003.7.1
Pyrazolium-3-carboxylates were examined as relatives of the betainic alkaloid Nigellicine and as new examples of the sparsely populated class 16 of heterocyclic pseudo-cross-conjugated mesomeric betaines (PCCMB). The title compounds were prepared in a 4-step procedure starting from beta-diketo compounds 8 which were cyclized with substituted hydrazines. The resulting isomeric pyrazole esters 9 and