Synthesis of indenones via palladium-catalyzed annulation of internal alkynes
摘要:
A number of 2,3-disubstituted 1-indenones have been prepared in fair to good yields by treating o-iodo- or o-bromobenzaldehyde with various internal alkynes in the presence of a palladium catalyst. Synthetically, the methodology provides an especially convenient route to stable hindered indenones containing aryl, silyl, and tert-alkyl groups. The reaction is believed to proceed through a palladium-(IV) intermediate, and the regiochemistry of the reaction is controlled sterically.
An Approach to One-Pot Regioselective Synthesis of Indenones through Palladium-Catalyzed Annulation in Water
作者:Karu Ramesh、Gedu Satyanarayana
DOI:10.1002/ejoc.201800591
日期:2018.8.15
A one‐pot synthesis of indenones, was presented. The reaction involved palladium catalyzed annulation of ortho‐halobenzaldehydes with internal alkynes. Notably, this process was successful in water as the sole green solvent. Significantly, unlike earlier reports, this protocol showed excellent regioselectivity with unsymmetrical alkylarylacetylenes. Further, the strategy was extended to a one‐pot synthesis
involve chlororhodation to the alkynes by the intermediary arylchlororhodium(III) species generated in situ followed by reductive elimination of the products, which are suggested by the results of some control experiments. In contrast to the reaction with terminal alkynes, that with some internal ones proceeds without decarbonylation to produce 2,3-disubstituted-1-indenones as the predominant products.
The rhodium(I)-catalyzed reaction of alkynes with 2-bromophenylboronic acids in the presence of paraformaldehyde resulted in a CO gas-free carbonylative cyclization, yielding indenone derivatives. [RhCl(BINAP)]2 and [RhCl(cod)]2 were responsible for the decarbonylation of formaldehyde and the subsequent carbonylation of alkynes with 2-haloboronic acids, respectively, leading to efficient whole carbonylation
reaction of alkynes with 2-bromophenylboronic acids under nitrogen gives naphthalene derivatives, in which two molecules of alkynes are incorporated. A vinylrhodium complex similar to II can also be generated by a different route by employing 2-bromophenyl(trimethylsilyl)acetylene and arylboronic acids in the presence of Rh(I) complex as the catalyst, resulting in the formation of indenones. The reaction
Palladium-catalyzed annulation of internal alkynes in aqueous medium
作者:Wei Jie Ang、Chih-Hsuan Tai、Lee-Chiang Lo、Yulin Lam
DOI:10.1039/c3ra46010j
日期:——
To facilitate precatalyst recovery and reuse, we have developed a fluorous, oxime-based palladacycle 1 and demonstrated that it is a very efficient and versatile precatalyst for carbo- and heteroannulation of internal alkynes with functionalized aryl halides in aqueous medium. A uniform reaction condition for these annulation reactions was also developed.