Regioselective Synthesis of Elusive 4,9-Dihydro-1H-Carbazoles by Gold-Catalyzed Cycloisomerization of 3-Allenylmethylindoles
摘要:
A general and efficient synthesis of 4,9-dihydro-1H-carbazoles from 3-allenylmethylindoles is reported. The process, catalyzed by a cationic gold(I) complex, involves a formal C2-H bond activation of the indole unit by reaction with the allene. The nature of the substituents at the allylic and terminal positions of the allene moiety has a crucial effect on the regioselectivity of the cyclization, which is also influenced by the catalyst and the solvent employed. Moreover, some evidence of the contribution of different reaction routes is provided, which led us to propose a plausible multipathway mechanism consistent with all of the results described.
Ferrocenium Cations as Catalysts for the Etherification of Cyclopropyl-Substituted Propargylic Alcohols: Ene-yne Formation and Mechanistic Insights
作者:Deva Saroja Talasila、Matthew J. Queensen、Michael Barnes-Flaspoler、Kellsie Jurkowski、Evan Stephenson、Jordan M. Rabus、Eike B. Bauer
DOI:10.1002/ejoc.201901330
日期:2019.11.30
Ferrocenium or ferrocenium boronic acid cations (Fc+) catalyze propargylic substitution reactions utilizing alcohol nucleophiles. Rearrangement to the corresponding ene‐ynes takes place with a cyclopropyl substituent. No cyclopropyl ring‐opening is observed with a thienyl substituent. An ionic mechanism is suggested for the reactions.
(EN) Described are a series of novel photochromic benzopyran and naphthopyran compounds substituted with (1) a cyclopropyl group and (2) a phenyl, substituted phenyl, or 5-member aromatic heterocyclic group at the 2-position of the benzopyran or naphthopyran ring. Also described are organic host materials that contain or that are coated with such compounds. Articles such as ophthalmic or plano lenses that incorporate the novel pyran compounds or combinations of the novel pyran compounds with other complementary photochromic compounds are described.(FR) On décrit une série de nouveaux composés benzopyraniques et naphthopyraniques photochromiques substitués avec (1) un groupe cyclopropylique et (2) un phényle, un phényle substitué, ou un groupe hétérocyclique aromatique à 5 membres dans la position-2 du cycle benzopyranique ou naphthopyranique. On décrit également des substances hôtes organiques contenant ou revêtues de tels composés. On décrit des articles tels que les lentilles ophthalmiques ou planes incorporant les composés pyraniques nouveaux ou des combinaisons de composés pyraniques nouveaux avec d'autres composés photochromiques.