436806-81-4Relevant articles and documents
The 5-endo-trig cyclization of gem-difluoroolefins with sp3 carbon nucleophiles: Synthesis of 1-fluorocyclopentenes
Ichikawa, Junji,Sakoda, Kotaro,Wada, Yukinori
, p. 282 - 283 (2007/10/03)
A disfavored 5-endo-trig cyclization is accomplished in gemdifluoroolefins with sp3 carbon nucleophiles, generated via the lithium - iodine exchange reaction of 1, 1-difluoro-5-iodo-1-pentenes with tert-butyllithium, to afford 1-fluorocyclopentenes.
The nucleophilic 5-endo-trig cyclization of 1,1-difluoro-1-alkenes: Ring-fluorinated hetero- and carbocycle synthesis and remarkable effect of the vinylic fluorines on the disfavored process
Ichikawa, Junji,Wada, Yukinori,Fujiwara, Masaki,Sakoda, Kotaro
, p. 1917 - 1936 (2007/10/03)
The disfavored 5-endo-trig cyclizations have been accomplished for 1,1-difluoro-1-alkenes with nitrogen, oxygen, sulfur, and carbon nucleophiles by taking advantage of the properties of fluorine. β,β-Difluorostyrenes bearing tosylamido, hydroxy, or methylsulfinyl group at the o-position undergo intramolecular nucleophilic substitution with a loss of the vinylic fluorine, leading to 2-fluorinated indole, benzo[b]furan, and benzo[b]thiophene in high yields, 1,1-Difluoro-1-butenes bearing homoallylic tosylamido, hydroxy, mercapto, or iodomethyl group also successfully cyclize via a 5-endo-trig process with the in situ generated intramolecular nucleophiles to afford 2-fluoro-2-pyrroline, 5-fluoro-2,3-dihydrofuran, 5-fluoro-2,3-dihydrothiophene, and 1-fluorocyclopentene. The two vinylic fluorines proved to be essential and play a critical role in these 'anti-Baldwin' cyclizations.
