67648-05-9Relevant articles and documents
Copper(I)-catalyzed regio- and stereoselective intramolecular alkylboration of propargyl ethers and amines
Iwamoto, Hiroaki,Ozawa, Yu,Kubota, Koji,Ito, Hajime
, p. 10563 - 10573 (2018/05/31)
The copper(I)-catalyzed regio- and stereoselective intramolecular alkylation of propargyl ethers and amines bearing an alkyl electrophilic moiety has been developed. The reaction showed high functional group tolerance and gave highly functionalized alkenylboronates bearing heterocyclic rings, which are versatile synthetic intermediates in organic chemistry. The borylation products can be transformed into multisubstituted alkenes through stereospecific transformations. Mechanistic studies showed that the chemo- and stereoselectivity of copper(I)-catalyzed borylation depends on the type of leaving group. Density functional theory calculations suggested that the regioselectivity of the borylcupration of the alkyne is controlled by the electronic effect of the oxygen atom of the propargyl ether in combination with the steric congestion between the boryl group and the substituent at the propargylic position.
A Method for the Late-Stage Formation of Ketones, Acyloins, and Aldols from Alkenylstannanes: Application to the Total Synthesis of Paecilonic Acid A
Sommer, Heiko,Hamilton, James Y.,Fürstner, Alois
supporting information, p. 6161 - 6165 (2017/05/22)
Treatment of alkenylstannanes with Cu(OAc)2/Et3N affords the corresponding enol esters or ketones under conditions that proved compatible with many common functionalities; these include groups that would neither survive under the sta
Two Enabling Strategies for the Stereoselective Conversion of Internal Alkynes into Trisubstituted Alkenes
Huwyler, Nikolas,Radkowski, Karin,Rummelt, Stephan M.,Fürstner, Alois
supporting information, p. 12412 - 12419 (2017/09/06)
An expedient method for the C-methylation of alkenylstannanes with formation of trisubstituted alkenes is described, which relies on the use of MeI in combination with copper thiophene-2-carboxylate (CuTC) as promotor and tetra-n-butylammonium diphenylphosphinate as an effective tin scavenger; in some cases, it proved beneficial to further supplement the mixture with catalytic amounts of Pd(PPh3)4. Under these conditions, the reaction is robust, high yielding, and compatible with many functional groups that might not subsist under more traditional conditions used to C-alkylate organotin derivatives. A qualitative analysis of the reaction profile suggested that the in situ formation of a reactive organocopper intermediate and its interception by MeI is only barely faster than O-methylation of the phosphinate additive by the same alkylating agent. To guarantee high yields and prevent net protodestannation from occurring, the reaction protocol had to be optimized such that these competing processes are properly decoupled. The new method is particularly well suited for the stereoselective preparation of the (E)-2-methylbut-2-en-1-ol motif that is present in numerous natural products. Alternatively, this particular target structure can be accessed starting from α-hydroxy alkenylsiloxane precursors, which get C-methylated upon exposure to CuI/LiOtBu and MeI by what is thought to be a Brook rearrangement/ alkylation sequence. The required substrates are best prepared by ruthenium-catalyzed trans-hydrosilylation or trans-hydrostannation of propargyl alcohols.
C-F bond cleavage enabled redox-neutral [4+1] annulation via C-H bond activation
Wang, Cheng-Qiang,Ye, Lu,Feng, Chao,Loh, Teck-Peng
supporting information, p. 1762 - 1765 (2017/02/15)
Using α,α-difluoromethylene alkyne as a nontraditional one-carbon reaction partner, a synthetically novel method for the construction of isoindolin-1-one derivatives via Rh(III)-catalyzed [4+1] annulation reaction is reported. The 2-fold C-F bond cleavage not only enables the generation of desired product under an overall oxidant-free condition but also results in a net migration of carbon-carbon triple bond. In addition, the present reaction protocol exhibits a tolerance of a wide spectrum of functional groups due to the mild reaction conditions employed.
Fluorine Effects on Group Migration via a Rhodium(V) Nitrenoid Intermediate
Wang, Cheng-Qiang,Zhang, Yu,Feng, Chao
supporting information, p. 14918 - 14922 (2017/10/12)
An unprecedented rhodium(III)-catalyzed hydroarylation of α,α-difluoromethylene alkynes with N-pivaloxyl aroylamides through sequential C?H activation and aryl migration is detailed herein. A large array of α,α-difluoromethylene alkynes and N-pivaloxyl aryl amides were amenable to this transformation, thus providing a novel synthetic protocol for the construction of difluorinated 2-alkenyl aniline derivatives in high yields and with excellent regioselectivity. Notably, unique fluorine effects were found to underlie the thus unconventional reaction manifold.
Synthesis of Vinyl-, Allyl-, and 2-Boryl Allylboronates via a Highly Selective Copper-Catalyzed Borylation of Propargylic Alcohols
Mao, Lujia,Bertermann, Rüdiger,Emmert, Katharina,Szabó, Kálmán J.,Marder, Todd B.
supporting information, p. 6586 - 6589 (2017/12/26)
An efficient methodology for the synthesis of vinyl-, allyl-, and (E)-2-boryl allylboronates from propargylic alcohols via Cu-catalyzed borylation under mild conditions is reported. In the presence of commercially available Cu(OAc)2 or Cu(acac)2 and Xantphos, the reaction affords the desired products in up to 92% yield with a broad substrate scope (43 examples). Isolation of an allenyl boronate as the reaction intermediate suggests that an insertion-elimination-type reaction, followed by borylcupration, is involved in the borylation of propargylic alcohols.
Hydroxyl-Assisted Carbonylation of Alkenyltin Derivatives: Development and Application to a Formal Synthesis of Tubelactomicin A
Sommer, Heiko,Fürstner, Alois
supporting information, p. 3210 - 3213 (2016/07/13)
Alkenyltin derivatives flanked by a hydroxyl group are subject to methoxycarbonylation when treated with catalytic amounts of Pd(OAc)2 and Ph3As in MeOH under a CO atmosphere; key to success is the use of 1,4-benzoquinone as a stoich
Electrocatalytic generation of amidyl radicals for olefin hydroamidation: Use of solvent effects to enable anilide oxidation
Zhu, Lin,Xiong, Peng,Mao, Zhong-Yi,Wang, Yong-Heng,Yan, Xiaomei,Lu, Xin,Xu, Hai-Chao
supporting information, p. 2226 - 2229 (2016/02/19)
Oxidative generation of synthetically important amidyl radicals from N-H amides is an appealing and yet challenging task. Previous methods require a stoichiometric amount of a strong oxidant and/or a costly noble-metal catalyst. We report herein the first electrocatalytic method that employs ferrocene (Fc), a cheap organometallic reagent, as the redox catalyst to produce amidyl radicals from N-aryl amides. Based on this radical-generating method, an efficient intramolecular olefin hydroamidation reaction has been developed. Easy access to N-arylamidyl radicals: The first electrocatalytic method for the generation of amidyl radicals from anilides has been developed using ferrocene (Cp2Fe) as a highly reactive, yet chemoselective redox catalyst. Based on this radical-generating method, a highly chemo- and diastereoselective olefin hydroamidation reaction has been developed.
Borylation of propargylic substrates by bimetallic catalysis. Synthesis of allenyl, propargylic, and butadienyl bpin derivatives
Zhao, Tony S. N.,Yang, Yuzhu,Lessing, Timo,Szabó, Kálmán J.
supporting information, p. 7563 - 7566 (2014/06/10)
Bimetallic Pd/Cu and Pd/Ag catalytic systems were used for borylation of propargylic alcohol derivatives. The substrate scope includes even terminal alkynes. The reactions proceed stererospecifically with formal S N2′ pathways to give allenyl boronates. Opening of propargyl epoxides leads to 1,2-diborylated butadienes probably via en allenylboronate intermediate.
Platinum-catalyzed hydrosilylations of internal alkynes: Harnessing substituent effects to achieve high regioselectivity
Rooke, Douglas A.,Ferreira, Eric M.
supporting information; experimental part, p. 3225 - 3230 (2012/05/31)
Rule of thumb: The high yielding title reaction is described with a focus on understanding the factors that govern the regioselectivity of the process (see scheme). Electronic, steric, and functional group properties all influence the selectivity, an understanding of which allows the selective formation of trisubstituted vinylsilanes, which are synthetically useful compounds for accessing stereodefined alkenes. Copyright
