A New Series of Proton/Charge Transfer Molecules: Synthesis and Spectral Studies of 2-(5-Aryl-1-carbomethoxy-1H-pyrazol-3-yl)phenols
作者:Mary E. Rampey、Carrie E. Halkyard、Angela R. Williams、April J. Angel、Douglas R. Hurst、Jessica D. Townsend、Anne E. Finefrock、Charles F. Beam、Shannon L. Studer-Martinez
DOI:10.1111/j.1751-1097.1999.tb07987.x
日期:1999.8
Abstract. The carbomethoxyhydrazone of 2′‐hydroxyacetophenone was trilithiated with excess lithium diisopropylamide and C‐acylated with a variety of benzoate esters followed by acid cyclization of the intermediates to 2‐(5‐aryl‐l‐car‐bomethoxy‐lHpyrazol‐3‐yl)phenols [3‐(2‐hydroxyphen‐yl)‐lH‐pyrazoles]. The products were characterized by Fourier transform‐IR, lH NMR, 13C NMR, UV‐visible absorption and fluorescence. All the derivatives in n ‐heptane have an absorption maximum at ˜304 nm and an extremely weak (φr= 10 4) fluorescence with maxima in the range of 335–460 nm. The broad range of fluorescence maxima and fluorescence quantum yields is attributed to varying contributions of charge transfer that are dependent on both the identity of the substituent and solvent polarity. A phenomenally large Stokes‐shifted fluorescence maximum at 620 nm was observed for 2‐(l‐car‐bomethoxy‐5‐[4‐dimethylaminophenyl]‐lff‐pyrazol‐3‐y1)phenol in n‐heptane and attributed to excited‐state intramolecular proton transfer. As a result, competitive excited‐state proton/charge transfer properties have been observed in the pyrazoles studied, of which the spectral properties can be fine tuned by substituent as well as solvent effects.
Preparation of 2<i>H</i>-spiro[benzo[<i>d</i>]isothiazole-3,3′-pyrazole]-1, 1-dioxide-2′(4′<i>H</i>)-carboxylates from dilithiated<i>C</i>(α),<i>N</i>-carboalkoxyhydrazones and methyl 2-(aminosulfonyl)benzoate
作者:Anna C. Dawsey、Chandra Potter、John D. Knight、Zachary C. Kennedy、Ellyn A. Smith、Amanda M. Acevedo-Jake、Andrew J. Puciaty、Clyde R. Metz、Charles F. Beam、William T. Pennington、Donald G. VanDerveer
DOI:10.1002/jhet.50
日期:2009.3
A variety of substituted spiro(benzoisothiazole-pyrazoles) have been prepared by the condensation of dilithiated C(α),N-carboalkoxyhydrazones with lithiated methyl 2-(aminosulfonyl)benzoate followed by the cyclization of intermediates with acetic anhydride, which also resulted in spiro N-acetylated products when carbomethoxyhydrazones or carboethoxyhydrazones were used, and spiro NH products when