Broad Range Of Alkenes Research Articles

Bromine Radical Catalysis by Energy Transfer Photosensitization.

We report here a mild, safe, and user-friendly bromine radical catalysis system that enables efficient [3 + 2] cycloaddition of diversely substituted vinyl- and ethynylcyclopropanes with a broad range of alkenes, including drug-like molecules and pharmaceuticals. Key to the success is the use of photosensitizing triplet-state β-fragmentation of a judiciously selected precatalyst, cinnamyl bromide, to generate bromine radicals in a controlled manner using parts per million-level photocatalyst (i.e., 4CzIPN) loading.

Iodonium Ylides Enable the Direct Installation of Hydroxylamines and Oximes into a Broad Range of Alkenes.

Described herein is an unprecedented method that enables the installation of hydroxylamines and oximes into a broad range of alkenes with iodonium ylides. For the first time, the single electron transfer process between iodonium ylides and oxygen-based Lewis bases was demonstrated in this transformation.

An Electrochemically Promoted, Nickel-Catalyzed Mizoroki–Heck Reaction

Despite significant efforts to replace Pd-based catalysts with those of Ni, the Ni-catalyzed Mizoroki–Heck coupling of aryl halides and alkenes remains challenging. This work details the development of a Mizoroki–Heck reaction of aryl halides and a broad range of alkenes that utilizes electrochemistry as a means to promote Ni-catalyzed coupling under mild conditions. Stoichiometric studies implicate low-valent Ni complexes as key intermediates in route to rapid reactions with even unactivated alkenes. As such, electrochemistry is employed to readily provide the reducing potentials necessary to access these reactive intermediates and render the transformation catalytic. Cyclohexenone was found to be an unreactive substrate but a crucial additive that promotes facile electroreduction of the Ni catalyst and functionalization of other alkenes in high yields. Finally, preliminary mechanistic studies suggest that reactions proceed via an electron-chain transfer process that rapidly terminates but is reinitiated...

Chiral Cyclopentadienyl Cobalt(III) Complexes Enable Highly Enantioselective 3d-Metal-Catalyzed C-H Functionalizations.

The synthesis of a set of cobalt(III)-complexes equipped with trisubstituted chiral cyclopentadienyl ligands is reported, and their steric and electronic parameters are mapped. The application potential of these complexes for asymmetric C-H functionalizations with 3d-metals is shown by the synthesis of dihydroisoquinolones from N-chlorobenzamides with a broad range of alkenes. The transformation proceeds with excellent enantioselectivities of up to 99.5:0.5 er and high regioselectivities. The observed values outperform the best rhodium(III)-based methods for this reaction type. Moreover, challenging substrates such as alkyl alkenes also react with high regio- and enantioselectivities.

Cp*RhIII-Catalyzed Allyl–Aryl Coupling of Olefins and Arylboron Reagents Enabled by C(sp3)–H Activation

Herein, we present a mild Cp*RhIII-catalyzed Suzuki–Miyaura-type allyl–aryl coupling of readily accessible arylboron reagents with a broad range of olefins. Allylic arylation was achieved without the need for prefunctionalized alkenes, and the general Heck-type reactivity between olefins and arenes was not observed. Mechanistic studies indicate that the reaction was enabled through the fast generation of a RhIII–allyl species via undirected C(sp3)–H activation. Moreover, the developed protocol was applied to the highly concise synthesis of the anti-inflammatory drug flurbiprofen.

Nickel-Catalyzed Stereoselective Arylboration of Unactivated Alkenes.

A Ni-catalyzed method for arylboration is disclosed. The method allows for highly stereoselective arylboration of unactivated alkenes. The reactions utilize a simple Ni-catalyst and work with a broad range of alkenes and aryl bromides. The products represent useful intermediates for chemical synthesis due to the versatility of the C-B bond. Preliminary mechanistic details of the method are also disclosed.

Isomerizing Methoxycarbonylation of Alkenes to Esters Using a Bis(phosphorinone)xylene Palladium Catalyst

The synthesis and characterization of bulky diphosphine 1,2-bis(4-phosphorinone)xylene, BPX, and its palladium complexes [(BPX)PdCl2] and [(BPX)Pd(O2CCF3)2] are described. BPX was evaluated as a ligand in Pd-catalyzed isomerizing methoxycarbonylation. A broad range of alkenes, including terminal, internal, branched, and functionalized alkenes, can be converted to esters with activities and selectivities matching or surpassing the performance of the state-of-the-art palladium bis(di(tert-butyl)phosphino-o-xylene (Pd-DTBPX) catalyst. A molecular structure of the precatalyst [(BPX)Pd(O2CCF3)2] was obtained showing a square planar geometry and a bite angle of 100.11(3)°. Rhodium carbonyl complexes [(BPX)Rh(CO)Cl] and [(DTBPX)Rh(CO)Cl] were synthesized to compare the relative electronic parameters, revealing a ν(C≡O) of 1956.8 and 1948.3 cm–1, respectively, suggesting a reduced ability of BPX to donate electron density to the metal relative to DTBPX. Competitive protonation experiments between BPX and DTBPX in...

ChemInform Abstract: Visible‐Light Promoted Intermolecular Halofunctionalization of Alkenes with N‐Halogen Saccharins.

AbstractThe photoreaction of N‐bromosaccharin with a range of alkenes leads to a mixture of bromoamide (V) and bromoether (VI).

ChemInform Abstract: Catalytic and Atom‐Economic Intermolecular Amidoselenenylation of Alkenes.

AbstractA broad range of alkenes, such as 1‐substituted, 1,1‐disubstituted as well as (E)‐ and (Z)‐1,2‐disubstituted olefins, including cyclic derivatives, react with N‐(phenylseleno)phthalimide to form amidoselenides in generally high yields and with high regio‐ and diastereoselectivities.

Difluorocarbene Addition to Alkenes and Alkynes in Continuous Flow.

The first in-flow difluorocarbene generation and addition to alkenes and alkynes is reported. The application of continuous flow technology allowed for the controlled generation of difluorocarbene from TMSCF3 and a catalytic quantity of NaI. The in situ generated electrophilic carbene reacts smoothly with a broad range of alkenes and alkynes, allowing the synthesis of the corresponding difluorocyclopropanes and difluorocyclopropenes. The reaction is complete within a 10 min residence time at high reaction concentrations. With a production flow rate of 1 mmol/min, continuous flow chemistry enables scale up of this process in a green, atom-economic, and safe manner.

Catalytic and Atom-Economic Intermolecular Amidoselenenylation of Alkenes.

A method for the simple, efficient, and atom-economic amidoselenenylation of simple alkenes under mild conditions using TiCl4 as a catalyst and N-(phenylseleno)phthalimide as both a nitrogen and selenium source was developed. A broad range of olefins can be applied to afford vicinal amidoselenides in good yield and with high regioselectivity and diastereoselectivity.

Zinc-catalyzed alkene cyclopropanation through zinc vinyl carbenoids generated from cyclopropenes.

The zinc-catalyzed reaction of cyclopropenes with alkenes leading to vinylcyclopropane derivatives is reported. A broad range of alkenes (including highly substituted or functionalized alkenes) is compatible with this protocol. On the basis of trapping experiments and computational studies, this cyclopropanation reaction is proposed to proceed through initial formation of an electrophilic zinc vinyl carbenoid intermediate, which may be involved in a concerted cyclopropanation reaction. The reported protocol represents an unprecedented and simple strategy for the catalytic generation of zinc vinyl carbenoids, which are promising intermediates in organic synthesis.

Zinc‐Catalyzed Alkene Cyclopropanation through Zinc Vinyl Carbenoids Generated from Cyclopropenes

AbstractThe zinc‐catalyzed reaction of cyclopropenes with alkenes leading to vinylcyclopropane derivatives is reported. A broad range of alkenes (including highly substituted or functionalized alkenes) is compatible with this protocol. On the basis of trapping experiments and computational studies, this cyclopropanation reaction is proposed to proceed through initial formation of an electrophilic zinc vinyl carbenoid intermediate, which may be involved in a concerted cyclopropanation reaction. The reported protocol represents an unprecedented and simple strategy for the catalytic generation of zinc vinyl carbenoids, which are promising intermediates in organic synthesis.

Iron-Catalyzed Diastereoselective Intramolecular Olefin Aminobromination with Bromide Ion.

A new iron-catalyzed diastereoselective aminobromination method is reported for both internal and terminal olefins (yield up to 90% and dr up to >20:1). In this transformation, a functionalized hydroxylamine and bromide ion were used as the nitrogen and bromine source, respectively. This method is compatible with a broad range of olefins and provides a convenient approach to synthetically valuable vicinal bromo primary amines. Our studies suggest that both the diastereoselectivity and enantioselectivity for the olefin aminobromination can be controlled by iron catalysts.

Catalytic Intermolecular Haloamidation of Simple Alkenes with N-Halophthalimide as Both Nitrogen and Halogen Source

A simple, efficient, and highly atom economic haloamidation of simple alkenes has been developed, using AgBF4 or InBr3/AgBF4 (1:3) as catalyst and N-halophthalimide as both nitrogen and halogen source. A broad range of olefins can be applied to afford vicinal haloamines in good yields and with high regioselectivity and diastereoselectivity.

Highly Stereoselective Olefin Cyclopropanation of Diazooxindoles Catalyzed by a C2-Symmetric Spiroketal Bisphosphine/Au(I) Complex

A spiroketal bisphosphine (SKP) derived chiral digold complex is identified as a powerful catalyst for the highly diastereo- and enantioselective synthesis of spirocyclopropyloxindoles from diazooxindoles and a broad range of alkenes, including both cis and trans 1,2-disubstituted alkenes.

Rhodium(III)-Catalyzed Direct Oxidative Cross Coupling at the C5 Position of Chromones with Alkenes

An atom-economical, Rh(III)-catalyzed, direct oxidative cross-coupling at the C5 position of chromones and flavones with a broad range of alkenes was developed. The products were formed in a highly regioselective manner in good to excellent yields. The developed method was applied in the cross-coupling of natural products for the synthesis of hybrid molecules.

Catalytic Intermolecular C-Alkylation of 1,2-Diketones with Simple Olefins: A Recyclable Directing Group Strategy

We describe the first example of Rh-catalyzed intermolecular C-alkylation of cyclic 1,2-diketones using simple terminal olefins as alkylating agents. Aminopyridine is employed as a recyclable directing group. First, it reacts with ketones to give enamines and delivers Rh to activate the vinyl C-H bonds in the same pot; second, it can be cleaved off and recovered via hydrolysis. A broad range of olefins can be utilized as substrates, including aliphatic, aromatic olefins and vinyl esters. The efficiency of this method is also demonstrated in the synthesis of a natural flavoring compound, 3-ethyl-5-methyl-1,2-cyclopentadione (one-pot 53% yield vs a previous four-step route 16% yield from the same starting material). This work is expected to serve as a seminal study toward catalytic ketone α-alkylation with unactivated olefins.

Iron-Catalyzed Aminohydroxylation of Olefins

We have discovered that N-sulfonyl oxaziridines react with a broad range of olefins in the presence of iron salts to afford 1,3-oxazolidines. This process provides access to 1,2-aminoalcohols with the opposite sense of regioselectivity produced from the copper-catalyzed oxyamination previously reported by our laboratories. Thus, either regioisomeric form of 1,2-aminoalcohols can easily be obtained from the reaction of oxaziridines with olefins, and the sense of regioselectivity can be controlled by the appropriate choice of inexpensive, nontoxic, first-row transition-metal catalyst.

Iron-catalyzed aminohydroxylation of olefins.

We have discovered that N-sulfonyl oxaziridines react with a broad range of olefins in the presence of iron salts to afford 1,3-oxazolidines. This process provides access to 1,2-aminoalcohols with the opposite sense of regioselectivity produced from the copper-catalyzed oxyamination previously reported by our laboratories. Thus, either regioisomeric form of 1,2-aminoalcohols can easily be obtained from the reaction of oxaziridines with olefins, and the sense of regioselectivity can be controlled by the appropriate choice of inexpensive, nontoxic, first-row transition-metal catalyst.