01057nas a2200169 4500008004100000245015900041210006900200260000800269300001600277490000600293520037500299100001600674700002200690700002000712700002400732856013100756 2006 eng d00aNovel synthesis of highly functionalized pyrazolines and pyrazoles by triphenylphosphine mediated reaction of dialkyl azodicarboxylate with allenic esters0 aNovel synthesis of highly functionalized pyrazolines and pyrazol cMAY a2213–22160 v83 a

Reaction of the Huisgen zwitterion, derived from triphenylphosphine and dialkyl azodicarboxylate, with allenic esters affords highly functionalized pyrazolines and pyrazoles. The crystal structure of pyrazoline derivative 7a showed extensive C−H···O interactions. Pyrazole formation proceeds via a novel nitrogen to carbon migration of the carboalkoxy group.

1 aNair, Vijay1 aBiju, Akkattu, T.1 aMohanan, Kishor1 aEringathodi, Suresh uhttps://library.ncl.res.in/content/novel-synthesis-highly-functionalized-pyrazolines-and-pyrazoles-triphenylphosphine-mediated01179nas a2200181 4500008004100000245016900041210006900210260000800279300001600287490000700303520037700310653008200687100001600769700002200785700002300807700002400830856014300854 2007 eng d00aNovel reaction of the “huisgen zwitterion” with chalcones and dienones: an efficient strategy for the synthesis of pyrazoline and pyrazolopyridazine derivatives0 aNovel reaction of the huisgen zwitterion with chalcones and dien cMAR a2070–20730 v463 a

Two unexpected transformations: The reaction of the Huisgen zwitterion derived from triphenylphosphane and diisopropyl azodicarboxylate (DIAD) with chalcones affords functionalized pyrazolines. In contrast, the reaction with dienones affords pyrazolopyridazines, presumably by Diels–Alder reaction of the initially formed pyrazoline with excess DIAD (see scheme).

10achalcones; nitrogen heterocycles; pyrazolines; synthetic methods; zwitterions1 aNair, Vijay1 aBiju, Akkattu, T.1 aMathew, Smitha, C.1 aEringathodi, Suresh uhttps://library.ncl.res.in/content/novel-reaction-%E2%80%9Chuisgen-zwitterion%E2%80%9D-chalcones-and-dienones-efficient-strategy-synthesis