Silver-Catalyzed Domino Reaction of ortho-Carbonylated Alkynyl-Substituted Arylaldehydes with Conjugated Dienes: Stereoselective Access to Indanone-Fused Cyclohexenes

Cascade Cyclization of o-(2-Acyl-1-ethynyl)benzaldehydes with Amino Acid Derivatives: Synthesis of Indeno[2,1-c]pyran-3-ones and 1-Oxazolonylisobenzofurans via the Erlenmeyer-Plöchl Azlactone Reaction

A highly regioselective divergent approach is reported for the synthesis of both indeno[2,1-c]pyran-3-one and 1-oxazolonylisobenzofuran derivatives using the Erlenmeyer-Plöchl azlactone (EPA) reaction. This approach involves the synthesis of o-(2-acyl-1-ethynyl)benzaldehydes, which reacted with various amino acids. Reaction with N-acylglycines resulted in the formation of indeno[2,1-c]pyran-3-ones, involving the sequential formation of two C-C bonds and two C-O bonds. Conversely, when the same conditions were applied to free amino acids, 1-oxazolonylisobenzofurans were obtained. This reaction involved the formation of a C-C bond between oxazolone and o-(2-acyl-1-ethynyl)benzaldehyde, followed by the formation of a C-O bond through a selective 5-exo-dig cyclization.

Straightforward Access to Isoindoles and 1,2-Dihydrophthalazines Enabled by a Gold-Catalyzed Three-Component Reaction

We describe herein a gold-catalyzed three-component reaction of o-alkynylbenzaldehydes, aryldiazonium salts, and trimethoxybenzene. This process enables the one-pot formation of valuable isoindoles and 1,2-dihydrophathalazines. The regioselectivity of the reaction is dictated by the nature of the aryldiazonium salt. Noticeably, the reaction is performed at room temperature under mild conditions and tolerates a variety of functional groups on both the o-alkynylbenzaldehyde and the aryldiazonium salt. Experimental mechanistic studies suggest that it is catalyzed by arylAu(III) species.

A regioselective [3 + 2] cycloaddition reaction of 2-benzylidene-1-indenones with functional olefins to access indanone-fused 2D/3D skeletons

The regioselective [3 + 2] cycloaddition reaction of 2-benzylidene-1-indenones with functional olefins was established with DABCO as a base under mild conditions. Using this approach, a series of diversely substituted indanone-fused cyclopentane polycycles with highly crowded multiple substituents were synthesized in high yields.

Navigating chemical reaction space - application to DNA-encoded chemistry

Databases contain millions of reactions for compound synthesis, rendering selection of reactions for forward synthetic design of small molecule screening libraries, such as DNA-encoded libraries (DELs), a big data challenge. To support reaction space navigation, we developed the computational workflow Reaction Navigator. Reaction files from a large chemistry database were processed using the open-source KNIME Analytics Platform. Initial processing steps included a customizable filtering cascade that removed reactions with a high probability to be incompatible with DEL, as they would e.g. damage the genetic barcode, to arrive at a comprehensive list of transformations for DEL design with applicability potential. These reactions were displayed and clustered by user-defined molecular reaction descriptors which are independent of reaction core substitution patterns. Thanks to clustering, these can be searched manually to identify reactions for DEL synthesis according to desired reaction criteria, such as ring formation or sp3 content. The workflow was initially applied for mapping chemical reaction space for aromatic aldehydes as an exemplary functional group often used in DEL synthesis. Exemplary reactions have been successfully translated to DNA-tagged substrates and can be applied to library synthesis. The versatility of the Reaction Navigator was then shown by mapping reaction space for different reaction conditions, for amines as a second set of starting materials, and for data from a second database.

Recent advances in transition-metal-catalyzed annulations for the construction of a 1-indanone core

Transition metal-catalyzed carbon–carbon bond forming reactions are a well accepted strategy for the synthesis of organic compounds. This review gives a brief update on the transition-metal-catalyzed annulations to construct 1-indanone scaffolds.

AgNTf2-catalyzed formal [3 + 2] cycloaddition of ynamides with unprotected isoxazol-5-amines: efficient access to functionalized 5-amino-1H-pyrrole-3-carboxamide derivatives

A formal [3 + 2] cycloaddition between ynamides and unprotected isoxazol-5-amines has been developed in the presence of catalytic AgNTf2 in an open flask. By the protocol, a variety of functionalized 5-amino-1H-pyrrole-3-carboxamide derivatives can be obtained in up to 99% yield. The reaction mechanism might involve the generation of an unusual α-imino silver carbene intermediate (or a silver-stabilized carbocation) and subsequent cyclization/isomerization to build the significant pyrrole-3-carboxamide motif. The reaction features the use of an inexpensive catalyst, simple reaction conditions, simple work-up without column chromatographic purification for most of products and high yields.

Synthesis of 4-(1H-isochromen-1-yl)isoquinolines through the silver-catalysed homodimerization of ortho-alkynylarylaldehydes and subsequent condensation of the 1,5-dicarbonyl motif with NH3

4-(1H-Isochromen-1-yl)isoquinoline derivatives were synthesized in high yields via the AgBF₄-catalyzed self-reaction of ortho-alkynylarylaldehydes to give isochromene intermediates, followed by the dehydration of the 1,5-dicarbonyl motif with NH₃. Compared with electron-rich aromatic substituents, this strategy can provide the desired isochromene products with an electron-deficient isoquinoline unit. The reactions feature simple experimental operations, mild reaction conditions and high product yields.

We demonstrate a strategy that can provide isochromenes with an electron-deficient isoquinoline unit. The reactions feature simple operations, mild conditions and high yields.

Iron/zinc-catalyzed benzannulation reactions of 2-(2-oxo-alkyl)benzketones leading to naphthalene and isoquinoline derivatives

An efficient method for the synthesis of poly-substituted naphthalenes/isoquinolines via Fe(iii)/Zn(ii)-catalyzed [4 + 2] cycloaddition of 2-(2-oxo-alkyl)benzketones is described.

Donor- and acceptor-enynals/enynones

Three kinds of transformations based on benzo-fused donor- and acceptor-enynals/enynones, including reactions with alkenes, alkynes, and H₂O, were discussed.

Chemoselective α-Methylenation of Aromatic Ketones Using the NaAuCl4/Selectfluor/DMSO System

Gold-catalyzed chemoselective α-methylenation of aromatic ketones was developed through the use of Selectfluor as a methylenating agent. A variety of useful 1,2-disubstituted propenone derivatives can be prepared in good yields via the present protocol. This reaction features a simple operation, good functional group tolerance, and broad scope of substrates.

Copper-catalyzed acyltrifluoromethylation of alkenes: rapid access to trifluoroethyl indanones and related compounds

Copper-catalyzed acyltrifluoromethylation of alkenes is described, affording trifluoroethyl indanones and related cyclic ketones in promising yields with excellent diastereoselectivity.