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Research has been conducted on the reaction mode of propyne iminium salts. The results of the intramolecular [4+2] cycloaddition between (het)arylethyne and olefin unit tethered by a cyclic iminium function are described.

A variety of 4-trifluoromethylquinolines bearing an aryl (or cyclopropyl, tert -butyl, trimethylsilyl) group at C-2 and a nitro group at ring position 6, 7 or 8 have been prepared in good to high yields from 3-substituted 1-(trifluoromethyl)prop-2-yne 1-iminium triflate salts and o -, m - or p -nitroaniline. These reactions include an aza-Michael reaction at room temperature followed by an intramolecular electrophilic aromatic substitution step, which requires additional thermal activation in most cases. In contrast, the conjugate addition of 2,4-dinitroanilines at the acetylenic iminium ions proceeds much more slowly and some of the adducts can be converted thermally into 2-(2,4-dinitrophenyl)-5-trifluoromethylpyrroles. Analogously, 2-(4-pyridyl)-5-trifluoromethylpyrroles were obtained from 3-aryl-1-(trifluoromethyl)propyn-iminium salts and 4-aminopyridinium triflate. A novel variation of the Truce–Smiles rearrangement is probably involved in the formation of these pyrroles. [ABSTRACT FROM AUTHOR]

The thermal isomerization of the 3,3-dimethylindoline-derived allenes, prepared through the organocuprate addition to 2-(phenylethynyl)-3,3-dimetthyl-1-methylindolium triflate, affords tetracyclic azepine derivatives. The spontaneous tautomerization of corresponding aminoallenes led to the formation of the semicyclic 2-amino 1,3-dienes.

1,3-Bis(trifluoromethyl)prop-2-ene 1-iminium triflate salts were prepared for the first time and some synthetic applications as 1,3-biselectrophilic building blocks were established. They were found to react with dimethoxybenzenes or methylene-1,2-dioxybenzenes to furnish vinylogous trifluoroacetylation products (4-aryl-1,1,1,5,5,5-hexafluoropent-3-en-2-ones) and 1-dialkylamino-1,3-bis(trifluoromethyl)-1 H -indenes. With aniline and ring-substituted anilines, 2,4-bis(trifluoromethyl)quinolines were formed. An unusual 4 H -pyran, formally a condensation product of the N , N -dimethyl-1,3-bis(trifluoromethyl)prop-2-en-1-iminium ion and its enaminone precursor, is also reported. [ABSTRACT FROM AUTHOR]

A convenient synthesis of 4‐trifluoromethyl‐quinolines from 1‐trifluoromethyl‐prop‐2‐yne 1‐iminium triflates and anilines in a one‐pot two‐step Michael addition/intramolecular cyclization sequence is reported. With ring‐substituted anilines, a wide range of 4‐CF3‐quinolines bearing additional substituents and functional groups in the C‐2, C‐6, and C‐8 positions were prepared, mostly in high yields. Even a 4‐CF3‐5‐Me‐quinoline could be obtained. From mono‐Boc protected 1,4‐ and 1,3‐phenylenediamine, 2‐aryl‐substituted 6‐amino‐4‐CF3‐quinoline and 7‐amino‐4‐CF3‐quinoline, respectively, were prepared. 4‐CF3‐benzo[h]quinolines were obtained from the mentioned acetylenic iminium salts and 1‐naphthylamine. With N‐monosubstituted aromatic amines such as N‐methylaniline and 1,2,3,4‐tetrahydroquinoline, N‐substituted 4‐CF3‐quinolinium salts and pyrrolo[1,2‐a:3,4‐c']diquinoline derivatives bearing two CF3 substituents could be prepared. [ABSTRACT FROM AUTHOR]

Compounds incorporating a 4-aza-8-oxabicyclo[3.2.1]oct-6-en-2-one moiety, which were prepared by a tandem carbenoid carbonyl ylide cyclization/[3+2]-cycloaddition reaction from ethyl 2-diazo-3-oxo-4-phthalimidobutanoates, undergo a nucleophile-induced two-bond ring cleavage when treated with protic heteronucleophiles. In this manner, tetrasubstituted furantricarboxylates, tethered with α-amino acids, esters, thioesters, and amides by a 2-carbonylphenyl moiety, are obtained. [ABSTRACT FROM AUTHOR]