126230-90-8Relevant articles and documents
INTRAMOLECULAR DIELS-ALDER REACTIONS OF QUATERNARY PYRAZINIUM SALTS AND PROTONATED PYRAZINIUM CATIONS. SYNTHESIS OF ANNELATED PYRIDINIUM SALTS AND ANNELATED PYRIDINES.
Geurtsen, Bart,Bie, Dick A. de,Plas, Henk C. van der
, p. 6519 - 6530 (2007/10/02)
Quaternization of alkynyl substituted pyrazines with triethyloxonium tetrafluoroborate in dichloromethane occurs exclusively at N-4 yielding 3-alkynyl-1-ethylpyrazinium salts, as shown by the 13C NMR data.Protonation of the same pyrazines with trifluoroacetic acid also occurs at N-4.The quaternary pyrazinium salts as well as the protonated pyrazines undergo an intramolecular Diels-Alder reaction under considerably milder conditions than the corresponding neutral pyrazines.The products of the reactions were -annelated quaternary pyridinium salts and -annelated protonated pyridinium cations, respectively.
SYNTHESIS OF 1,3-DIHYDROFUROPYRIDINES AND 5,7-DIHYDROFUROPYRIDINES BY INTRAMOLECULAR DIELS-ALDER REACTIONS OF PYRIMIDINES. INVESTIGATION OF THE EFFECT OF STERIC INTERACTIONS ON THE REACTION RATE
Frissen, A. E.,Marcelis, A. T. M.,Buurman, D. G,Pollmann, C. A. M.,Plas, H. C. van der
, p. 5611 - 5620 (2007/10/02)
Several 2- and 5-propynyloxymethylpyrimidines were synthesized and their intramolecular Diels-Alder reaction was studied.The products of the reaction were 5,7-dihydrofuropyridines and 1,3-dihydrofuropyridines, respectively.Introduction of on
