We have developed a hybrid system of metal/Brønsted acid relay catalysis for the intramolecular double hydroarylation and cationic cyclization of diyne diethers and diamines to give 4,4'-bi(2H-chromene), bi(2H-quinoline), and dioxafluoranthenes starting from 2,4-diyne-1,6-diethers and diamines in one reaction vessel under mild conditions.
A synthetic method was developed for the preparation of vinyl sulfides and vinylamines from arylalkynyl phenyl sulfides and sulfonamides. Under mild conditions, a catalytic intramolecular hydroarylation reaction was carried out in the presence of FeCl3 and AgOTf (OTf = trifluoromethanesulfonate) in 1,2‐dichloroethane. A variety of 1,2‐dihydronaphthalenes, 2H‐chromenes, and 1,2‐dihydroquinolines containing a phenylsulfenyl or N‐phenyl‐N‐tosyl group on the sp2‐hybridized benzylic carbon were prepared in good to excellent yields. The present method could be extended to the preparation of dihydropyrano[2,3‐g]chromenes through a twofold Fe‐catalyzed hydroarylation by a selective 6‐endo mode.
We report aza-[4+3] annulation through sequential [3+2]-[2+1] cycloadditions-aza-Cope rearrangement for the synthesis of dihydroazepines. Aza-[3+2] annulation was achieved through [3+2]-[2+1]-aza-Cope rearrangement-1,3migration or [3+2]-[2+1]-Clock rearrangement, leading to the formation of dihydropyrroles. In addition, dihydroazepines thermally 1,3-migrated to give dihydropyrroles. This method affords a straightforward synthetic pathway from simple triazoles to produce dihydroazepines and dihydropyrroles together with N 2 as the single byproduct. This procedure can be successfully applied to a one-pot process starting from terminal alkynes, azides, and dienes.Azaheterocycles are a highly important class of compounds due to their biological activities and pharmaceutical applications. [1] In particular, dihydroazepines, dihydropyrroles, and pyrroles are constituents of a valuable privileged structure in organic chemistry. [2] For this reason, the development of efficient synthetic methods for producing multisubstituted azaheterocyclic compounds from simple and easily accessible starting materials has been continuously required. [3] Now, we report an efficient aza-[4+3] annulation and aza-[3+2] annulation starting from terminal alkynes, sulfonyl azides, and 1,3-dienes in one-pot (Scheme 1).Recently, 1-sulfonyl-1,2,3-triazoles, which are easily prepared from copper-catalyzed 1,3-dipolar cycloaddition of terminal alkynes with sulfonyl azides, have been extensively investigated as precursors of a-imino metal carbenes. [4] The high reactivity of a-imino metal carbenes toward nucleophiles is caused by the intrinsically electrophilic properties of the metal carbene species. In addition, a-imino metal carbenes can react with electrophiles because the nitrogen atom of the a-imino group is inherently nucleophilic. Accordingly, these amphiphilic a-imino metal carbenes smoothly react with nitriles, [5]
An efficient synthetic method of 1,4-dihydronaphthalenes having various alkyl groups on the 4-position and/or ethoxycarbonyl group on the 2-position through selective intramolecular Pt-catalyzed 6-endo cyclohydroarylation of ethyl 2-benzyl-2,3-alkadienoates was developed. The present method could be further extended to two-fold Pt-catalyzed 6-endo and 7-endo cyclizations.
Tandem gold-catalyzed addition of alkynyl phosphonic acid monoethyl esters to terminal alkynes and cyclization were developed for the synthesis of 4,6-disubstituted phosphorus 2-pyrones in one reaction vessel based on the concept of sequential alkyne activation. Alkynyl enol phosphonates were selectively obtained through the gold-catalyzed addition reaction in the presence of a catalytic amount of triethylamine. Also, gold-catalyzed cyclization of alkynyl enol phosphonates was successful in giving a variety of 4,6-disubstituted phosphorus 2-pyrones.
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