Strain control in nucleophilic cyclizations: Reversal of exo-selectivity in cyclizations of hydrazides of acetylenyl carboxylic acids by annealing to a pyrazole scaffold

Sergei F. Vasilevsky, Brian Gold, Tatyana F. Mikhailovskaya, Igor V. Alabugin

Результат исследований: Материалы для журналаСтатья

18 Цитирования (Scopus)

Аннотация

Independent of the nature of alkyne substitution, hydrazides of 4-arylethynyl-5-carboxylic acid annealed at the pyrazole scaffold undergo a regioselective base-catalyzed 6-endo-dig cyclization with the formation of pyrazolo [3,4-c]pyridine-7-ones. This behavior contrasts the observation of selective 5-exo closures in the analogous benzannelated systems and illustrates selective destabilization of the reaction path leading to the formation of a smaller ring. Computational analysis also reveals an important role of prototropic equilibria in rendering the overall cyclization feasible in the strained heterocyclic systems. The switch to the formation of a larger cycle suggests that strategic incorporation of strain can be used as a tool for the efficient control of regiochemistry of nucleophilic cyclizations.

Язык оригиналаАнглийский
Страницы (с-по)998-1005
Число страниц8
ЖурналJournal of Physical Organic Chemistry
Том25
Номер выпуска11
DOI
СостояниеОпубликовано - 1 ноя 2012
Опубликовано для внешнего пользованияДа

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry

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