87691-76-7Relevant academic research and scientific papers
Pyrylium Compounds. 33. 2-Dialkylamino-2H-thiopyrans from 2,4,6-Triaryl-thiopyrylium Salts
Zimmermann, Thomas,Fischer, Gerhard W.
, p. 567 - 572 (2007/10/02)
2,4,6-Triaryl-thiopyrylium salts 7 react with dialkylamines in diethyl ether to give stable crystalline 2-dialkylamino-2H-thiopyrans 8, the structure of which is in accordance with their u.v., n.m.r. and mass spectra.The chemical properties of 8 parallel those of structurally analogous 2-alkoxy- and 2-dialkylamino-2H-pyrans and 2-alkoxy-2H-thiopyrans.Thus, on heating 2-dimethylamino-2,4,6-triphenyl-2H-thiopyran (8a) with methanol the corresponding 2-methoxy-2H-thiopyran 9 is formed.Nitromethane and ethyl cyanoacetate give rise to ring transformations yielding 1,3,5-triphenyl benzene (10) and 2,4,6-benzonitrile (11), respectively.From 8a electrophiles (e.g. mineral acids, methyl iodide, benzoyl chloride) regenerate the initial thiopyrylium system by taking over the dialkylamino group.
Rates and Equilibria of the Reaction of 2,4,6-Triphenylthiopyrylium Ion with Piperidine and Morpholine in Me2SO. An Unusual Proton Transfer to a Nitrogen Base
Doddi, Giancarlo,Ercolani, Gianfranco
, p. 7082 - 7087 (2007/10/02)
The complete set of kinetic and equilibrium constants of the reaction of 2,4,6-triphenylthiopyrylium ion (1) with piperidine and morpholine has been obtained in Me2SO at 25 deg C.The reaction involves the formation of both the corresponding 2H- and 4H-thiopyrans, which equilibrate to form only the more stable 2H adduct.The kinetic data are consistent with a two-step process wherein the proton transfer form the protonated 2H- and 4H-thiopyran intermediates to the amine is the rate-controlling step.The thermodynamically favored proton transfer to the neutral adducts by the solvated proton shows a rate below the diffusion limit, whwreas the observed Broensted coefficient would indicate a diffusion-controlled process.This behavior is discussed in terms of the Eigen mechanism.The factors affecting the nucleophilic addition are discussed, and a comparison is made with the previously reported reaction of 1 with primary amines.
