Synthesis of 6H-Dibenzo[b,d]pyran-6-ones from Aryl 3-Bromopropenoates via a Sequential One-Pot Procedure Using the Sonogashira Coupling−Benzannulation Reaction
摘要:
Various kinds of 6H-dibenzo [b,d] pyran-6-ones 4 were synthesized via a sequential one-pot procedure using the Sonogashira coupling-benzannulation reaction of aryl 3-bromopropenoates 1, in which the ortho-position of aryl group is substituted with enynes or iodine, with acetylenes 2 in the presence of palladium and copper catalysts. The Sonogashira coupling between the aryl 3-bromopropenoates 1a and 1b, bearing enynes at the ortho-position of aryl group, and alkynes 2a-g gave the enyne intermediates 3 in situ, which subsequently underwent the palladium-catalyzed benzannulation reaction to afford the 6H-dibenzo [b,d] pyran-6-ones 5a-g and 6. The Sonogashira coupling between the aryl 3-bromopropenoate le, bearing iodine at the ortho-position of aryl group, and diynes 2f and 2h produced the diyne intermediates 13, which underwent the benzannulation reaction to afford the 6H-dibenzo[b,d]pyran-6-ones 14f and 14h.
electrophilicity of the allylpalladium intermediates enables the regioselectively intramolecular 1,2-addition of enynol in the presence of aminal. This aminomethylation and cyclization reaction via C–N bond activation and intramolecular nucleophilic addition provides a rare example for the synthesis of O-containing heterocycle-confined 1,3-dienes, which is of synthetic potential for further derivatization. The method
Rhodium(I) catalysts promote the transformation of o-alkynyl phenols and anilines to the corresponding benzo[b]furans and indoles. The reaction is postulated to proceed via a transient 3-rhodium heterocycle intermediate, which can be trapped with suitable electrophiles to give poly-substituted heterocycles. In the case of mono-substituted electron-withdrawn electrophiles, excellent yield and selectivity
铑(I)催化剂促进邻炔基苯酚和苯胺转化为相应的苯并[ b ]呋喃和吲哚。假定该反应通过过渡的3-铑杂环中间体进行,该中间体可以用合适的亲电试剂捕获以得到多取代的杂环。在单取代的吸电子亲电体的情况下,与Heck-Mizoroki反应相比,可以获得优异的收率和选择性。在2-炔基吡啶亲电试剂的情况下,形成新的2-(苯并呋喃-3-基)乙烯基吡啶。
A Cascade Sonogashira Cross‐Coupling‐Substitution‐Elimination Reaction for the Synthesis of Linear Conjugated Dienynes
A Sonogashira cross-coupling, nucleophilic substitution and elimination cascade reaction allows the synthesis of otherwise difficult to obtain linear dienynes, in moderate to high yields. Ionic liquids are suitable recyclable solvents for the reaction. This synthetic strategy opens new ways to prepare highly conjugated alkenes and alkynes.
Rhodium(I)-Catalyzed Cyclization Reaction of <i>o</i>-Alkynyl Phenols and Anilines. Domino Approach to 2,3-Disubstituted Benzofurans and Indoles
作者:Naohiro Isono、Mark Lautens
DOI:10.1021/ol9001174
日期:2009.3.19
A rhodium-catalyzed cyclization of o-alkynylphenols and anilines followed by intermolecular conjugate addition that succeeds with alkyl and aryl alkynes is reported. In this reaction, 2,3-disubstituted benzofurans or indoles are obtained in one pot in good to excellent yields.
Preparation of Chiral Allenes through Pd-Catalyzed Intermolecular Hydroamination of Conjugated Enynes: Enantioselective Synthesis Enabled by Catalyst Design
作者:Nathan J. Adamson、Haleh Jeddi、Steven J. Malcolmson
DOI:10.1021/jacs.9b02637
日期:2019.5.29
surrogate to afford primary amines in a two-step/one-pot process. Examination of chiral catalysts revealed a high degree of reversibility in the C-N bond formation that negatively impacted enantioselectivity. Consequently, an electron-poor ferrocenyl-PHOX ligand was developed to enable efficient and enantioselective enyne hydroamination.