1392013-91-0Relevant articles and documents
Regioselective 5-endo-dig Electrophilic Iodocyclization of Enediynes: A Convenient Route to Iodo-substituted Indenes and Cyclopenta-Fused Arenes
Saunthwal, Rakesh K.,Danodia, Abhinandan K.,Patel, Monika,Kumar, Sushil,Verma, Akhilesh K.
supporting information, p. 3001 - 3007 (2016/11/13)
An efficient iodine-mediated regioselective tandem approach for the synthesis of symmetric and asymmetric iodo-substituted indenes and stereoselective cyclopenta [b]pyridine/thiophenes from easily accessible enediynes that proceeds by in situ formation of an iodonium intermediate followed by a regioselective 5-endo-dig cyclization has been described. The intramolecular electrophilic iodocyclization was selectively triggered by a distribution of electronic density along the alkyne bond. Subsequently, the iodo-substituted indenes were diversified by employing palladium-catalyzed cross-coupling reactions and the coupled products were further confirmed by X-ray crystallographic studies.
Synthesis of 2-(hetero)arylthieno[2,3-b] or [3,2-b]pyridines from 2,3-dihalopyridines, (hetero)arylalkynes, and Na2S. Further functionalizations
Peixoto, Daniela,Begouin, Agathe,Queiroz, Maria-Jo?o R.P.
experimental part, p. 7082 - 7094 (2012/08/28)
A simple and efficient three-step methodology is described for the first time for the synthesis of 2-(hetero)arylthieno[2,3-b] or [3,2-b]pyridines. The first step is a Sonogashira coupling from 3-bromo-2-chloropyridine or 2-bromo-3-chloropyridine with several (hetero)arylalkynes to obtain the corresponding 2- or 3-chloro(hetero)arylethynylpyridines. These were cyclized by treatment with Na2S affording the expected 2-(hetero) arylthienopyridines. As an improvement, these reactions were also performed in one-pot, without the isolation of the Sonogashira product, giving the thienopyridines in similar or better yields, reducing significantly the reaction time after the addition of Na2S. Further functionalizations were achieved in the thienopyridine system either by bromination in the thiophene ring or chlorination in the pyridine ring via a N-oxide intermediate, allowing metal-catalyzed coupling reactions and/or nucleophilic substitutions. The functionalization of some substituents is also possible and as an example a 1,3-diarylurea was obtained from the reaction of an aniline derivative with an arylisocyanate.
