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Type: Artigo de periódico
Title: Intrinsic gas-phase reactivity of ionized 6-(Oxomethylene)cyclohexa-2,4-dienone: Evidence pointing to its neutral alpha-oxoketene counterpart as a proper precursor of various benzopyran-4-ones and analogues
Author: de Carvalho, PS
Nachtigall, FM
Eberlin, MN
Beraldo Moraes, LA
Abstract: Despite its unique structure and potential use as an important building block in organic synthesis, the title alpha-oxoketene 1 has been formed mostly under very special conditions as a short-lived species. The reactivity of 1 is, therefore, nearly unexplored. In great contrast, it seemed that its ionized gaseous form 1(center dot+) is stable and easily accessible. In this study, we used multiple-stage pentaquadrupole mass spectrometry to probe the formation of gaseous 1(center dot+) and explore its stability and intrinsic reactivity. With water and methanol, gaseous 1(center dot+) was found to react similarly to solvated 1, which indicates that there is a close parallel between their reactivities. Gaseous 1(center dot+) was also found to react promptly via polar [3 + 2] cycloadditons with various dienophiles including alkenes, alkynes, isocyanates, ketones and esters, thus forming a series of benzopyran-4-ones (flavones, 4-chromanones, 4-chromenones, benzo[1,3]dioxin-4-ones, and analogues) that are common structural units in many natural products. The present availability of 1 at room temperature and the gas-phase findings reported herein for gaseous 1(center dot+) indicate that solvated 1 should undergo many [4 + 2] cycloadditions and functions as a versatile precursor of a variety of biologically active molecules.
Country: EUA
Editor: Amer Chemical Soc
Rights: fechado
Identifier DOI: 10.1021/jo070371z
Date Issue: 2007
Appears in Collections:Unicamp - Artigos e Outros Documentos

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