Unsaturated Carbanions, Heterocumulenes and Thiocarbonyl Compounds − New Routes to Heterocycles

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

“…Essentially it involves the use of heterocumulenes (isothiocyanates, isocyanates) and carbanions readily generated in situ from available alkynes or 1,2-and 1,3-dienes, as key building blocks. The results of these investigations were summarized and analyzed in dissertations [98,148,149] and in recently published reviews and monographs [99,101,[150][151][152][153][154][155][156][157][158][159][160][161][162][163][164][165].…”

Six‐Membered Heterocycles: Pyridines

“…A good example of this approach has also been reported by Brandsma and coworkers [131,132] in the synthesis of pyridine derivatives 154 (Scheme 16.39). Reaction of lithiated allene 149, obtained from allenes 147 or methylacetylenes 148, with alkylthioisocyanate 150 and subsequent alkylation affords adduct 151, which isomerizes via [1,5]-hydrogen shift, quantitatively, under mild reaction conditions to generate 1,3-butadienyliminoformates 152.…”

Utilities of Some Carbon Nucleophiles in Heterocyclic Synthesis

“…Here the cyclization of the adduct 279 clearly takes place by mechanism of nucleophilic substitution (Scheme 88). The reaction of alkyl and cycloalkyl isothiocyanate with lithium derivatives of alkoxyallenes under analogous conditions leads to the formation of mixtures of 3-alkoxypyrroles and 5alkoxy-2,3-dihydropiperidines [42,161]. The reaction of alkyl and cycloalkyl isothiocyanate with lithium derivatives of alkoxyallenes under analogous conditions leads to the formation of mixtures of 3-alkoxypyrroles and 5alkoxy-2,3-dihydropiperidines [42,161].…”