6628-22-4Relevant academic research and scientific papers
Catch-and-release of HNO with pyrazolones
Guthrie, Daryl A.,Ho, Anthony,Takahashi, Cyrus G.,Collins, Anthony,Morris, Matthew,Toscano, John P.
, p. 1338 - 1348 (2015/02/19)
A new and versatile class of HNO donors, the (hydroxylamino)pyrazolone (HAPY) series of HNO donors utilizing pyrazolone (PY) leaving groups, is described. HNO, the smallest N-based aldehyde equivalent, is used as a reagent along with a variety of PY compounds to synthesize the desired HAPY donors in what can be considered an N-selective HNO-aldol reaction in up to quantitative yields. The bimolecular rate constant of HNO with PY in pH 7.4 phosphate buffer at 37 °C can reach 8 × 105 M-1 s-1. In 1H NMR experiments, the HAPY compounds generate HNO quantitatively (trapped as a phosphine aza-ylide) with half-lives spanning 3 orders of magnitude (minutes to days) under physiologically relevant conditions. B3LYP/6-31G calculations confirm the energetically favorable reactions between HNO and the PY enol and enolate, whereas HNO release is expected to occur through the oxyanion (OHN-PY) of each HAPY compound. HNO has been shown to provide functional support to failing hearts.
N,N-dialkyl-N′-chlorosulfonyl chloroformamidines in heterocyclic synthesis. Part VIII. Novel pyrazolo-fused oxathiadiazines and thiatriazoles
Forsyth, Craig M.,Francis, Craig L.,Jahangiri, Saba,Liepa, Andris J.,Perkins, Michael V.,Young, Anna P.
scheme or table, p. 659 - 668 (2010/09/05)
N,N-dialkyl-N′-chlorosulfonyl chloroformamidines 1 reacted with pyrazol-3-ones 2 under a variety of conditions to give pyrazolo[2,3-e][1,2,3,5] oxathiadiazine dioxides 3 and pyrazolo[3,2-b][1,4,3,5]oxathiadiazine dioxides 5, and frequently, one or both of pyrazolo[1,2-b][1,2,3,5]thiatriazole 1,1,5-trioxides 4 and 1,1,7-trioxides 6. In all reactions, the pyrazolo[3,2-b][1,4,3,5]oxathiadiazine 5 was the major product, with the pyrazolo[2,3-e][1,2,3,5]oxathiadiazine 3 being a significant product in the absence of base. Prior to our recent work, the core ring systems of compounds 3 and 5 had not been reported and compounds 4 and 6 are new derivatives of a rare ring system. CSIRO 2010.
Tautomerism-dependent ring construction of N-heterocyclic compounds from the reactions of 1-alkynyl fischer carbene complexes and substituted pyrazolinones
Zheng, Zhaoyan,Yu, Zhengkun,Luo, Ning,Han, Xiuwen
, p. 9695 - 9700 (2007/10/03)
Four types of N-heterocyclic ring systems were successfully constructed from the reactions of 1-alkynyl Fischer carbene complexes (OC) 5M=C(OEt)C≡CPh (1) (M = Cr, W) and substituted pyrazolinones (2). Reactions of 1 with 3-methyl-2-pyrazolin-5-one (2a), 3-n-propyl-2- pyrazolin-5-one (2b), 3,4-dimethyl-2-pyrazolin-5-one (2c), 3,4-trimethylene-2- pyrazolin-5-one (2d), or 3,4-tetramethylene-2-pyrazolin-5-one (2e) generated three kinds of Fischer aminocarbene complexes (3-5), and reactions of 1 with phenyl-substituted pyrazolinones, i.e., 3-phenyl-2-pyrazolin-5-one (2f) and its tautomer 3-phenyl-3-pyrazolin-5-one (2g), gave Fischer alkoxycarbene complexes (6) as the major products and aminocarbene complexes of types 3-5 as the minor products. Multiple tautomerism of pyrazolinones is attributed to the versatile formation of N-heterocyclic Fischer carbene complexes. Oxidative demetalation of complexes 3-6 with pyridine N-oxide or m-chloroperoxybenzoic acid efficiently afforded organic carbonyl products, and thus, strongly fluorescent syn-mixed-bimanes were prepared. The present findings constitute an alternative new method to synthesize mixed bimanes and other novel N-heterocyclic compounds.
NEW TYPE OF CONDENSATION OF 5-PYRAZOLONES UNSUBSTITUTED AT THE NITROGEN
Grandberg, I. I.,Nam, N. L.
, p. 540 - 543 (2007/10/02)
1,5-Tripyrazolylenes were prepared with satisfactory yields by the reaction of 5-pyrazolones unsubstituted at the nitrogen atom with an equimolar amount of POCl3 in open vessels together with 5-chloro derivatives (Michaelis reaction).
