Given the importance of alkenylsilanes in organosilicon chemistry and material science, direct transition-metal-catalyzed selective hydrosilylation of alkynes with hydrosilanes has emerged as apowerful platform for accessing such building blocks in a straightforwardand atom-economical fashion [1,2]. Among them,regio- and stereoselective hydrosilylations of terminal alkynesand symmetrical internal alkynes have been thoroughly studied,and a range of 3d transition-metal catalysts exhibited excellentb-(E), b-(Z), and a-selectivity in these transformations [3–9].Despite these major advances, crucial drawbacks exist in thecatalytic hydrosilylation between hydrosilanes and unsymmetricalinternal alkynes, particularly when done in a regiodivergent andstereocontrolled fashion. The representative examples are largelyrestricted to the use of electronically [10] or sterically [11] biasedalkynes (Fig. 1a).
Jixin WangJie LinZhili CuiJianlin YaoKonstantin KaraghiosoffJie Li
Lewis base catalyzed and Brønsted acid controlled chemodivergent electrophilic selenofunctionalizations of alkynes were developed for the first time.Various selenium-containing tetrasubstituted alkenes were readily obtained in moderate to excellent yields with complete E/Z selectivities.As the substrates were 1-ethynyl naphthol derivatives,linear selenium-containing tetrasubstituted alkenes were produced via intermolecular oxygen nucleophilic attack in the absence of acid additive;in contrast,cyclic selenium-containing tetrasubstituted alkenes were generated through intramolecular carbon nucleophilic capture with the addition of Brønsted acid.
The rhodium-catalyzed C-H bond activation and cyclization of 3-oxopent-4-enenitriles with alkynes proceed efficiently.Various 2H-pyrans with multiple substituents are achieved in good yields through regioselective formation of C-O and C-C bonds.Transformations involving hydroxy-alkynoates resulted in products with a furo[3,4-b]pyran skeleton via further intramolecular ester exchange processes.Different from the traditional"1-oxatrienes pathway",this method for the synthesis of useful 2H-pyrans possesses certain highlights in terms of readily available substrates,stable and easily derivatized products,gentle and convenient operation process,and step and atomeconomy.
Kelu YanXiao LiuJiangwei WenQiuyun LiJunjie WangYang ZhengXiu Wang
An efficient and sustainable protocol for regioselective hydrocarboxylation of alkynes to construct diverse propionic acid derivatives is disclosed.Under photoinduced conditions,the anti-Markovnikov hydrocarboxylation of alkynes was realized with CO_(2) radical anion in-situ generated from formate as both a carbonyl source and a reductant.The collaboration between photosensitizer and hydrogen atom transfer catalyst promoted the catalytic cycle to work smoothly,giving a broad substrate scope including terminal and internal alkynes.The Giese radical addition of CO_(2) radical anion to the C—C triple bond is the key step to initiate the reaction.
Carbon dioxide reduction, as a sustainable and versatile strategy for the access of chemical fuels, has attracted increasing attention and enormous efforts have been devoted to it in recent years. However, employing carbon dioxide as double synthons via bimolecular reduction remains challenging. Here, by leveraging the bimolecular reduction of carbon dioxide to carbonyl and methyl respectively, we describe a Pd-catalyzed trifunctionalization of alkynes with aryl iodide for the first time and showcase its advantages on the formation of various β-diketones and their application in the constructing of heterocyclic compounds with important biological activity, including pyrimidine, oxazole, pyrazole.
Comprehensive Summary,The azepine ring is a prominent structural scaffold in biologically significant molecules. In this study, we present a Ni(II)-catalyzed asymmetric difunctionalization of alkynes, involving intermolecular regioselective arylation and intramolecular nitrile addition, enabling the synthesis of enantioenriched azepine derivatives. This reaction simultaneously installs an all-carbon quaternary stereocenter and introduces an unprotected imine functionality, showing great promise for subsequent transformations. The reaction exhibits good tolerance toward various functional groups, resulting in high yields and enantioselectivities. The synthetic utility of this methodology is further demonstrated through gram-scale synthesis and product derivatization. This research offers an efficient approach to the synthesis of seven-membered nitrogen heterocycles.
Difunctionalization of alkynes represents a powerful and straightforward approach to the synthesis of complex molecules.However,the radical difunctionalization of alkynes mediated by bifunctional reagents remains challenging and underexplored,despite significant progress having been made in alkene difunctionalization.Here,we report a novel arylsulfonylacetate skeleton in which aryl rings are attached to acetates through SO_(2),serving as a powerful bifunctional reagent for the alkylarylation of alkynes via vinyl-radical intermediate under photoredox conditions.This modular bifunctional reagent enables the simultaneous incorporation of a wide range of functional groups,including(hetero)aryl ring and alkyl carboxylate into alkynes,resulting in synthetically valuable all-carbon tetrasubstituted alkene derivatives.This transformation is distinguished by its redox-neutral nature,readily accessible starting materials,compatibility with diverse functional groups and its capacity to facilitate convergent synthesis.The utility of this approach was further demonstrated by the late-stage functionalization of complex molecules and the preparation of fluorescent molecules and anti-cancer drugs.
