79823-43-1Relevant academic research and scientific papers
Reaction of Ketone Alkylhydrazones with Phosphorus Trichloride: a General Mild Route to Substituted Pyrroles
Baccolini, Graziano
, p. 1053 - 1056 (2007/10/02)
A new convinient and mild procedure for the synthesis of symmetrically and unsymmetrically substituted pyrroles is described.This one-pot synthesis consists of two different stages.The first stage, addition of PCl3 to an alkylhydrazone, is always carried out at room temperature.The second stage, addition of an enolizable ketone to the previous reaction mixture, is performed at room temperature, or at 80 deg C under reduced pressure.The results provide clear evidence that diazaphsphole derivatives being formed in the first stage are intermediates in this pyrrole synthesis.
Synthesis of Pyrroles under Mild Conditions using PCl3, Ketones, and Alkylhydrazines
Baccolini, Graziano,Sandali, Claudio
, p. 788 - 789 (2007/10/02)
A one-pot synthesis of symmetrical pyrroles was obtained by reaction of alkylhydrazones of enolizable ketones, PCl3, and subsequent addition of the same ketone.
Stereoisomer Effects on the Paal-Knorr Synthesis of Pyrroles
Szakal-Quin, Gyoengyi,Graham, Doyle G.,Millington, David S.,Maltby, David A.,McPhail, Andrew T.
, p. 621 - 624 (2007/10/02)
The neurotoxicity of n-hexane has been postulated to result from the reactivity of its γ-diketone metabolite, 2,5-hexanedione (1), with lysil amino groups of proteins to form pyrroles (Paal-Knorr synthesis).We have synthesized a series of 3,4-disubstituted γ-diketones in order to explore the relationship between rate of pyrrole formation and neurotoxicity.The γ-diketones were prepared through oxidative coupling of ketones.Yields were improved to 60-70percent with the use a Soxhlet apparatus containing PbO2 in the extraction thimble.Diketones prepared were 3,4-dimethylhexane-2,5-dione (2), 3,4-diethylhexane-2,5-dione (3), 3,4-diisopropylhexane-2,5-dione (4), and 3,4-diphenylhexane-2,5-dione (5).The reactions yielded mixtures of the d,l (a) and meso (b) diastereomers, which were separated by column chromatography, fractional distillation, or crystallization.Structures of the diastereomeric forms were established by 13C NMR techniques and, in the case of 4b, by single crystal X-ray diffraction.The relative reactivities of the d,l and meso isomers of each γ-diketone were determined with benzylamine in cyclohexane and the rate of pyrrole formation was determined by HPLC.For each pair of diastereomeric diketones the d,l reacted 4-40 times faster than the meso form.The reactivities of the γ-diketones were in the order 2 > 1 > 3 > 5 > 4 with pseudo-first-order rate constants ranging from 4*10-4 to 3*10-8 s-1 at 30 deg C.
Heterocycles from Nitroalkenes, I. - Pyrroles via Michael Addition of Enamines
Meyer, Horst
, p. 1534 - 1544 (2007/10/02)
The principle of a general pyrrole synthesis via cyclising Michael addition of enamines to nitroalkenes is outlined.Condensation of the nitroalkene 7 with various enamines yields the pyrroles 9, 11, 12, 14, 15, 17, 18, 20, 22, 26, 27, 29, and 31.Reaction of 1-nitro-1,2-diphenylethene and the enamine 8 furnishes the pyrroloisoquinoline 32 while addition of 8 to 1-nitrocyclohexene is followed by ring closure to the indoloisoquinoline 33.The pyrrole 14 can also be prepared by multiple-component syntheses, further examples of which are the syntheses of the pyrroles 35, 36, 37, and 38.Scope and advantages of the presented pyrrole synthesis are discussed.
