Search

Safranine-catalyzed oxidative cyclization reaction of substituted 2-aminobenzamides and aldehydes utilizing oxygen as a green oxidant under visible light conditions at room temperature has been developed. Good to excellent yields of the desired quinazolinone products were achieved. Furthermore, the presented procedure illustrates the applicability of gram scale reactions. [ABSTRACT FROM AUTHOR]

Abstract: A rhodium‐catalyzed intramolecular [3+2] cycloaddition of 1‐allene‐vinylcyclopropanes (1‐allene‐VCPs) to construct cyclopentane‐embedded bicyclic structures with quaternary stereocenters at the bridgehead position has been developed with good to excellent yields. In addition, this transformation could also be conducted on a large scale with reduced catalyst loading, which could be useful for further derivatizations and applications. [ABSTRACT FROM AUTHOR]

• Efficient photocatalytic synthesis of sulfoxides from sulfides with good yields. • The method was achieved under visible light irradiation and ambient temperature conditions. • Gram-scale synthesis of sulfoxides was successfully conducted. • Photocatalytic oxidations of arylboronic acids and 2,3-dihydroquinazolinones were also investigated. Bay-annulated indigo (BAI), an old red dye first produced in 1914, which shows good performance as electron-accepting units in photovoltaic and semiconducting applications, was utilized as an organic photocatalyst for the first time. Under the irradiation of blue LEDs, organic sulfides can be selectively oxidized to corresponding sulfoxides with good to excellent yields. In addition, the photocatalytic oxidations of arylboronic acids and 2,3-dihydroquinazolinone derivatives were also investigated, indicating that it is a very promising organic photocatalyst for much more applications. [Display omitted] [ABSTRACT FROM AUTHOR]

The article presents chemical equations related to the article "Fe2(CO)9-Mediated [5 + 1] Cycloaddition of Vinylcyclopropanes and CO for the Synthesis of Cyclohexenones" by Cheng-Hang Liu and others, published in the journal "Tetrahedron" in 2016.

Reported herein is the first rhodium-catalyzed [4+2+1] cycloaddition of in situ generated ene/yne-ene-allenes and CO to synthesize challenging seven-membered carbocycles fused with five-membered rings. This reaction is designed based on the 1,3-acyloxy migration of ene/yne-ene-propargyl esters to ene/yne-ene-allenes, followed by oxidative cyclization, CO insertion, and reductive elimination to form the final [4+2+1] cycloadducts. The possible competing [4+1], [4+2], and [2+2+1] cycloadditions were disfavored, making the present reaction an efficient way to access functionalized 5/7 rings., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Previously reported was that cis-ene-vinylcyclopropanes (cis-ene-VCPs) underwent Rh-catalyzed [5+2] reaction to give 5,7-fused bicyclic products, where vinylcyclopropane (VCP) acts as five-carbon synthon. Unfortunately, this reaction had very limited scope. Replacing the 2π component of cis-ene-VCPs to allene moiety, the corresponding cis-allene-VCPs did not undergo the expected normal [5+2] cycloaddition to give 5,7-fused bicyclic products. Instead, the challenging bicyclo[4.3.1]decane skeleton was obtained via an unprecedented bridged [5+2] cycloaddition. DFT calculations were applied to understand why this bridged [5+2] reaction is favored over the anticipated but not realized normal [5+2] reaction., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A Rh-catalysed [5 + 1] cycloaddition of allenylcyclopropanes and CO has been developed to synthesize functionalized 2-methylidene-3,4-cyclohexenones. The scope of this methodology has been investigated, showing that various functional groups can be tolerated. Both di- and tri-substituted allenylcyclopropanes can be applied to this cycloaddition and the [5 + 1] cycloadducts with the E configuration were obtained as the major products. In addition, the present [5 + 1] cycloaddition reaction has been utilized as a key step in the formal synthesis of the natural product (-)-galanthamine.