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We herein report a modular one‐step three‐component protocol for the assembly of isochromans, which involved a Catellani/oxa‐Michael addition cascade. This approach features readily available starting materials, mild reaction conditions, low palladium catalyst loading, good scalability as well as high step‐ and atom‐economy. [ABSTRACT FROM AUTHOR]

Reported here is a concise total synthesis of (−)‐berkelic acid in eight linear steps. This synthesis features a Catellani reaction/oxa‐Michael cascade for the construction of the isochroman scaffold, a one‐pot deprotection/spiroacetalization operation for the formation of the tetracyclic core structure, and a late‐stage Ni‐catalyzed reductive coupling for the introduction of the lateral chain. Notably, four stereocenters are established from a single existing chiral center with excellent stereocontrol during the deprotection/spiroacetalization process. Stereocontrol of the intriguing deprotection/spiroacetalization process is supported by DFT calculations. [ABSTRACT FROM AUTHOR]

Reported is a cooperative catalytic system consisting of a complex of Pd with dicyclohexyl(2′,4′,6′-triisopropylbiphenyl-2-yl)phosphine (XPhos) and the potassium salt of 5-norbornene-2-carboxylic acid that permits the use of epoxides as dual-functionalized alkylating reagents in Catellani-type reactions for the assembly of heterocycles. Salient features of this research include readily available substrates, use of the potassium salt of 5-norbornene-2-carboxylic acid as a catalytic mediator as well as a base, and excellent regioselectivity for the cleavage of epoxides. This mild, chemoselective, scalable, atom- and step-economic protocol offers a straightforward approach for the assembly of isochroman and 2,3-dihydrobenzofuran scaffolds. [ABSTRACT FROM AUTHOR]

Abstract: We report a cooperative catalytic system comprising a PdII complex, XPhos, and the potassium salt of 5‐norbornene‐2‐carboxylic acid that enables the use of epoxides as alkylating reagents in the Catellani reaction, thereby expanding the existing paradigm of this powerful transformation. The potassium salt of inexpensive 5‐norbornene‐2‐carboxylic acid acts as both mediator and base in the process. This mild, chemoselective, scalable, and atom‐economical protocol is compatible with a wide variety of readily available functionalized aryl iodides and epoxides, as well as terminating olefins. The resulting products undergo facile oxa‐Michael addition to furnish ubiquitous isochroman scaffolds. [ABSTRACT FROM AUTHOR]

A new synthetic method for α-alkynyl-α,β-unsaturated esters is presented herein. The method is based on a copper(I)-catalyzed three-component reaction of a terminal alkyne, diazoesters and aldehydes. The reaction is featured by mild conditions, high yields and excellent stereoselectivity. Cu(I) carbene migratory insertion is proposed as the key step in the transformation. [ABSTRACT FROM AUTHOR]

A transition-metal-free difluoromethylenation of diazo compounds that proceeds under mild conditions has been developed and is based on the use of TMSCF2Br as the difluoromethylene source and tetrabutylammonium bromide (TBAB) as the promoter. The chemoselective formal carbene dimerization reaction is achieved owing to the electronic properties and the relative stability of the difluorocarbene intermediate. [ABSTRACT FROM AUTHOR]

The Accepted Article version of the above article, published online on 25 May 2021 in Wiley Online Library (wileyonlinelibrary.com), has been withdrawn by agreement between the corresponding author, the journal′s Executive Committee, and Wiley‐VCH GmbH, Weinheim. The withdrawal has been agreed upon due to significant conceptual similarities with another of the authors' recently published articles, which was not disclosed during the peer review process. [ABSTRACT FROM AUTHOR]

The Accepted Article version of the above article, published online on 25 May 2021 in Wiley Online Library (wileyonlinelibrary.com), has been withdrawn by agreement between the corresponding author, the journal′s Executive Committee, and Wiley‐VCH GmbH, Weinheim. The withdrawal has been agreed upon due to significant conceptual similarities with another of the authors' recently published articles, which was not disclosed during the peer review process. [ABSTRACT FROM AUTHOR]

A diagram is presented which shows the allenylphosphonate synthesis through copper-catalyzed coupling of alkynes with diazophosphonates.

The article presents chemical equations related to the article "Cu(I)-Catalyzed Coupling of Diaryldiazomethanes with Terminal Alkynes: An Efficient Synthesis of Tri-Aryl-Substituted Allenes" by Chenggui Wu published in the "Tetrahedron" in 2015.

We present a new [3+2] cycloaddition reaction between alkyl-acceptor diazoalkanes under visible light irradiation. By employing easily accessible alkyl-acceptor-type diazoalkanes or their precursor hydrazones as both 1,3-dipoles and dipolarophiles, a diverse range of pyrazoline derivatives featuring a quaternary center have been efficiently synthesized in a predictable manner, with excellent functional group tolerance and good yields. Furthermore, scale-up experiments and downstream transformations of the product were also detailed.

Reported here is a concise total synthesis of (-)-berkelic acid in eight linear steps. This synthesis features a Catellani reaction/oxa-Michael cascade for the construction of the isochroman scaffold, a one-pot deprotection/spiroacetalization operation for the formation of the tetracyclic core structure, and a late-stage Ni-catalyzed reductive coupling for the introduction of the lateral chain. Notably, four stereocenters are established from a single existing chiral center with excellent stereocontrol during the deprotection/spiroacetalization process. Stereocontrol of the intriguing deprotection/spiroacetalization process is supported by DFT calculations., (© 2020 Wiley-VCH GmbH.)

Reported is a modular strategy for the preparation of the unique benzofused dioxabicycle scaffolds involving a Catellani reaction of aryl iodides, epoxides, and terminal alkynes and an oxa -cyclization. This is a mild, scalable, chemoselective, and atom-economical protocol, compatible with various functionalized aryl iodides, epoxides, and terminal alkynes. With the ability to build up the molecular complexity rapidly and efficiently from feedstock chemicals, this method will have wide applications in organic synthesis.

Silver-catalyzed tandem cyclization-elimination reactions of conjugated ene-yne-ketones in PhI(OAc) 2 /triethylamine system lead to the formation of 2-alkenylfurans. 2-Furylsilver carbene and phenyliodonium ylide are proposed as the key intermediates in these transformations.

A Cu-catalyzed three-component cross-coupling reaction of terminal alkyne, α-diazo ester, and alkyl halide has been developed. This transformation involves sequent migratory insertion of copper-carbene and nucleophilic substitution, in which a C(sp)-C(sp(3)) bond and a C(sp(3))-C(sp(3)) bond are formed successively on a carbenic center. Michael addition acceptors can also be employed instead of alkyl halides that enable Michael addition to be an alternative way to build C(sp(3))-C(sp(3)) bond. This transformation represents a highly efficient method for the construction of all-carbon quaternary centers.