Addition reactions of heterocyclic compounds. Part LVII. Reactions of pyridines with acetylenic esters in the presence of carbanion sources

Pyridine-Mediated N-Vinylation of Heterocyclic Compounds: A Mild, Stereoselective and General Synthesis

“…The compounds 3a-h were characterised by 1 H, 13 C NMR and IR spectroscopy and elemental analyses. 9 Compounds 3i-m were new and their structures were deduced by elemental and spectral analysis.…”

“…A tentative mechanism for this transformation is proposed in Scheme 2. On the basis of the well-established reactivity of pyridines [12][13][14][15][16][17][18][19] with acetylene carboxylates it is reasonable to assume that the compound 3 arises from initial addition of the pyridine to the acetylenic ester 2 and subsequent protonation of the 1 : 1 adduct 4 by compound 1. This adduct is then attacked by the anion of 1 in a Michael fashion to produce 7.…”

Ph3P promoted one-pot synthesis of dialkyl 2-(2-oxopyridin-1(2H)-yl)but-2-enedioates from a reaction of 2-hydroxypyridine and dialkyl acetylenedicarboxylates

“…[17][18][19][20][21][22][23][24] The addition reaction between electron-deficient acetylenic compounds and nitrogen-containing hetrocycles has been extensively investigated. 25,26 We report here that dialkyl acetylenedicarboxylates 1 undergo addition reaction with 2hydroxypyridine (2) in the presence of Ph 3 P, yielding dialkyl (Z)-and (E)-2-(2-oxopyridin-1(2H)-yl)but-2-enedioates 3 in good yields.…”

A Simple Synthesis of N-Vinylpyrrole, N-vinylindole and N-Vinylcarbazole Derivatives

“…4,10 As a result, much effort has been devoted to the development of new methodologies for efficient synthesis of vinylpyrroles and vinylindoles. [5][6][7][8][9][10][11][12][13][14][15][16][17][18] Because of their electron-rich characteristics, pyrrole and indole react readily with a wide range of electrophiles. Substitution of pyrrole usually takes place most readily at the 2-position while indole almost always reacts with electrophiles at the 3-position.…”