1,3-Diaza-1,3-butadienes. Synthesis and Conversion into Pyrimidines by [4π + 2π] Cycloaddition with Electron Deficient Acetylenes. Synthetic Utility of 2-(Trichloromethyl)pyrimidines1
摘要:
Methods have been devised to generate 1H-1,3-diaza-1,3-butadienes bearing a leaving group at position-4 in latent, masked, and unprotected forms. A hallmark of these azadienes is that they undergo thermal [4 pi + 2 pi] cycloaddition reactions with electron deficient acetylenes to give adducts which are aromatized to pyrimidine derivatives under the reaction conditions. Thus, 1-(methoxycarbonyl)-3-acylamidines 17 on beating in solution are converted in situ into the 1,3-diaza-1,3-dienes 18 and/or 19 which react with dimethyl acetylenedicarboxylate (DMAD) to produce the pyrimidines 20. The 1-Boc-1,3-diaza-1,3-dienes 24 are masked forms of the LH-dienes inasmuch as they react with DMAD under relatively mild conditions to give the dihydropyrimidine adducts 25, which are easily detectable by H-1 NMR spectroscopy, and which aromatize to pyrimidines 26 at higher temperatures. The 4-methylthio compounds 31 and 33, and the 2-(trichloromethyl) compounds 37, are isolable, relatively stable, 1H-1,3-diaza-1,3-butadienes, These easily prepared compounds react with electron deficient acetylenes under mild conditions to provide the pyrimidines 20, 34, and 38, respectively, in fair to excellent yields. The 2-(trichloromethyl)pyrimidines 38 are very useful precursors of a wide variety of other 2-substituted pyrimidines 46-52.
A new method for the conversion of trichloromethyl compounds into the corresponding thiolacetates by treatment with sodium thiolacetate in the presence of thiolacetic acid is described. This transformation proceeds at room temperature in high yield when a strong electron-withdrawing substituent is attached to the trichloromethyl group.
A new method for the conversion of trichloromethyl compounds into the corresponding phenylthiomethyl derivatives by reaction with sodium thiophenolate in the presence of thiophenol is described. This transformation proceeds at room temperature in high yield and has been applied to a variety of trichloromethyl compounds.
Synthesis of pyrimidines from 2-trichloromethyl-4-dimethylamino-1,3-diaza-1,3-butadienes and electron deficient acetylenes
作者:Angel Guzmán、Moisés Romero、Francisco X. Talamás、Joseph M. Muchowski
DOI:10.1016/s0040-4039(00)92660-1
日期:1992.6
2-Trichloromethyl-4-dimethylamino-1,3-diaza-1,3-butadienes(3), prepared from trichloroacetamidine(1) and amide acetals 2, readily react with electron deficient acetylenes 4 to give 2-trichloromethylpyrimidines 5.
A new synthesis of 2-substituted-1,3-dithianes from trichloromethyl compounds
Trichloromethyl compounds are efficiently converted into 1,3-dithianes upon reaction with a disodium 1,3-propanedithiolate-1,3-propanedithiol mixture in DMF solution at 0 degrees C. This synthesis is limited to those substrates where the substituent attached to the trichloromethyl group is an electron-withdrawing group. (c) 2006 Elsevier Ltd. All rights reserved.
Chemoselective Reduction of Trichloromethyl Compounds to <i>gem</i>-Dichloromethyl Groups Following Appel’s Reaction Protocol
作者:Moises A. Romero-Reyes、Ivann Zaragoza-Galicia、Horacio F. Olivo、Moises Romero-Ortega
DOI:10.1021/acs.joc.6b02044
日期:2016.10.7
trichloroacetyl compounds following the modification of Appel’s reaction protocol, using triphenylphosphine and methanol, afforded the corresponding dichloroacetyl compounds, with the exception of trichloroacetylmorpholine, in yields of 80–98% under very mild experimental conditions. Likewise, when trichloromethyl heterocyclic compoundscontain another reactive functional group, the reaction is highly chemoselective