- Stereodivergent Nucleophilic Additions to Racemic β-Oxo Acid Derivatives: Fast Addition Outcompetes Stereoconvergence in the Archetypal Configurationally Unstable Electrophile
-
Additions of carbon nucleophiles to racemic α-stereogenic β-oxo acid derivatives that deliver enantiomerically enriched tertiary alcohols are valuable, but uncommon. This article describes stereodivergent Cu-catalyzed borylative cyclizations of racemic β-oxo acid derivatives bearing tethered pro-nucleophilic olefins to deliver highly functionalized cyclopentanols containing four contiguous stereogenic centers. The reported protocol is applicable to a range of β-oxo acid derivatives, and the diastereomeric products are readily isolable by typical chromatographic techniques. α-Stereogenic-β-keto esters are typically thought to have extreme or spontaneous configurational fragility, but mechanistic studies for this system reveal an unusual scenario wherein productive catalysis occurs on the same time scale as background substrate racemization and completely outcompetes on-cycle epimerization, even under the basic conditions of the reaction.
- Crawford, Evan T.,De Jesús Cruz, Pedro,Johnson, Jeffrey S.,Liu, Shubin
-
supporting information
p. 16264 - 16273
(2021/10/21)
-
- Vinyl Sulfonium Salts as the Radical Acceptor for Metal-Free Decarboxylative Alkenylation
-
Vinyl sulfonium salts typically act as an electrophilic Michael acceptor, thus initiating many tandem cyclization reactions. Herein, we disclosed the novel reactivity of vinyl sulfonium salts as a radical acceptor. Using redox-active ester as an alkyl rad
- Zhang, Yu-Lan,Yang, Lei,Wu, Jie,Zhu, Chunyin,Wang, Peng
-
p. 7768 - 7772
(2020/10/09)
-
- A Simple Nickel Catalyst Enabling an E-Selective Alkyne Semihydrogenation
-
Stereoselective alkyne semihydrogenations are attractive approaches to alkenes, which are key building blocks for synthesis. With regards to the most atom-economic reducing agent dihydrogen (H2), only few catalysts for the challenging E-selective alkyne semihydrogenation have been disclosed, each with a unique substrate scope profile. Here, we show that a commercially available nickel catalyst facilitates the E-selective alkyne semihydrogenation of a wide variety of substituted internal alkynes. This results in a simple and broadly applicable overall protocol to stereoselectively access E-alkenes employing H2, which could serve as a general method for synthesis.
- Thiel, Niklas O.,Kaewmee, Benyapa,Tran Ngoc, Trung,Teichert, Johannes F.
-
supporting information
p. 1597 - 1603
(2020/02/05)
-
- Remote Functionalization of α,β-Unsaturated Carbonyls by Multimetallic Sequential Catalysis
-
The remote functionalization of α,β-unsaturated carbonyls by an array of multimetallic sequential catalytic systems is described. The reactions are triggered by hydrometalation using [Pd-H] or [Ru-H] isomerization catalysts and driven by the formation of thermodynamically more stable 1,2-vinyl arenes. The Pd-catalyzed deconjugative isomerization was combined with a Cu-catalyzed β-borylation of the transiently generated styrenyl derivatives to deliver a range of products that would not be accessible with the use of a single catalyst. [Pd/Cu] catalytic systems were also identified for the highly enantioselective α-hydroboration and α-hydroamination of the styrenyl intermediates. Difunctionalization simultaneously at the benzylic and homobenzylic positions was achieved by combining the isomerization process with Sharpless asymmetric dihydroxylation (SAD) using [Pd/Os] or [Ru/Os] couples. Starting from a simple α,β-unsaturated ester, an isomerization/dihydroxylation/lactonization sequence gave access to a naturally occurring γ-butyrolactone in good yield, with excellent diastereo- and enantioselectivity.
- Romano, Ciro,Fiorito, Daniele,Mazet, Clément
-
p. 16983 - 16990
(2019/10/28)
-
- Bidentate auxiliary-directed alkenyl C-H allylation: Via exo-palladacycles: Synthesis of branched 1,4-dienes
-
An alkenyl C-H allylation by an exo-palladacycle intermediate is demonstrated, employing unactivated (Z)-Alkenes and allyl carbonates. With the use of an 8-Aminoquinoline (AQ) derived amide as the directing group, the N,N-bidentate-chelation-Assisted C-H activation protocol proceeded under mild and oxidant-free conditions with excellent selectivity. The utility of this approach is demonstrated by the preparative scale, selective conversion of inseparable Z/E alkenes and ready removal of the amide auxiliary to provide the corresponding ester.
- Shen, Cong,Lu, Xiunan,Zhang, Jian,Ding, Liyuan,Sun, Yaling,Zhong, Guofu
-
supporting information
p. 13582 - 13585
(2019/11/14)
-
- Iron-Catalyzed Vinylic C?H Alkylation with Alkyl Peroxides
-
A variety of alkyl peresters and alkyl diacyl peroxides, which are readily accessible from carboxylic acids, are utilized as general primary, secondary, and tertiary alkylating reagents for iron-catalyzed vinylic C?H alkylation of vinyl arenes, dienes, and 1,3-enynes. This transformation affords olefinic products in up to 98 % yield with high E/Z values. A broad range of functionalities, including carboxyl, boronic acid, methoxy, ester, amino, and halides, are tolerated. This protocol provides a facile approach to some olefins that are difficult to access, and hence, offers an alternative to existing systems. The synthetic utility of this method is demonstrated by late-stage functionalization of selected natural-product derivatives.
- Ge, Liang,Jian, Wujun,Zhou, Huan,Chen, Shaowei,Ye, Changqing,Yu, Fei,Qian, Bo,Li, Yajun,Bao, Hongli
-
supporting information
p. 2522 - 2528
(2018/08/01)
-
- Tridentate Directing Groups Stabilize 6-Membered Palladacycles in Catalytic Alkene Hydrofunctionalization
-
Removable tridentate directing groups inspired by pincer ligands have been designed to stabilize otherwise kinetically and thermodynamically disfavored 6-membered alkyl palladacycle intermediates. This family of directing groups enables regioselective remote hydrocarbofunctionalization of several synthetically useful alkene-containing substrate classes, including 4-pentenoic acids, allylic alcohols, homoallyl amines, and bis-homoallylamines, under Pd(II) catalysis. In conjunction with previous findings, we demonstrate regiodivergent hydrofunctionalization of 3-butenoic acid derivatives to afford either Markovnikov or anti-Markovnikov addition products depending on directing group choice. Preliminary mechanistic and computational data are presented to support the proposed catalytic cycle.
- O'Duill, Miriam L.,Matsuura, Rei,Wang, Yanyan,Turnbull, Joshua L.,Gurak, John A.,Gao, De-Wei,Lu, Gang,Liu, Peng,Engle, Keary M.
-
supporting information
p. 15576 - 15579
(2017/11/14)
-
- Catalytic olefin hydroamination with aminium radical cations: A photoredox method for direct C-N bond formation
-
While olefin amination with aminium radical cations is a classical method for C-N bond formation, catalytic variants that utilize simple 2° amine precursors remain largely undeveloped. Herein we report a new visible-light photoredox protocol for the intramolecular anti-Markovnikov hydroamination of aryl olefins that proceeds through catalytically generated aminium radical intermediates. Mechanistic studies are consistent with a process involving amine oxidation via electron transfer, turnover-limiting C-N bond formation, and a second electron transfer step to reduce a carbon-centered radical, rendering the overall process redox-neutral. A range of structurally diverse N-aryl heterocycles can be prepared in good to excellent yields under conditions significantly milder than those required by conventional aminium-based protocols.
- Musacchio, Andrew J.,Nguyen, Lucas Q.,Beard, G. Hudson,Knowles, Robert R.
-
p. 12217 - 12220
(2014/12/09)
-
- The first palladium-catalyzed 1,4-addition of terminal alkenes to acrylate esters
-
A novel and efficient procedure for the synthesis of δ,γ- alkenyl esters with complete E-stereochemistry by the 1,4-addition of alkenes to acrylate esters in the presence of a catalytic amount of palladium chloride has been developed. This method provides
- Liu, Pei,Wang, Heng-Shan,Pan, Ying-Ming,Dai, Wei-Long,Liang, Hong,Chen, Zhen-Feng
-
supporting information
p. 5295 - 5297
(2013/06/27)
-
- Enantioselective thiourea-catalyzed intramolecular cope-type hydroamination
-
Catalysis of Cope-type rearrangements of bis-homoallylic hydroxylamines is demonstrated using chiral thiourea derivatives. This formal intramolecular hydroamination reaction provides access to highly enantioenriched α-substituted pyrrolidine products and represents a complementary approach to metal-catalyzed methods.
- Brown, Adam R.,Uyeda, Christopher,Brotherton, Carolyn A.,Jacobsen, Eric N.
-
supporting information
p. 6747 - 6749
(2013/06/05)
-
- Synthesis of trans-disubstituted alkenes by cobalt-catalyzed reductive coupling of terminal alkynes with activated alkenes
-
A cobalt-catalyzed reductive coupling of terminal alkynes, RC≡CH, with activated alkenes, R'CH=CH2, in the presence of zinc and water to give functionalized trans-disubstituted alkenes, RCH=CHCH2CH 2R', is described. A variety of aromatic terminal alkynes underwent reductive coupling with activated alkenes including enones, acrylates, acrylonitrile, and vinyl sulfones in the presence of a CoCl2/P(OMe) 3/Zn catalyst system to afford 1,2-trans-disubstituted alkenes with high regio- and stereoselectivity. Similarly, aliphatic terminal alkynes also efficiently participated in the coupling reaction with acrylates, enones, and vinyl sulfone, in the presence of the CoCl2/P(OPh)3/Zn system providing a mixture of 1,2-trans- and 1,1-disubstituted functionalized terminal alkene products in high yields. The scope of the reaction was also extended by the coupling of 1,3-enynes and acetylene gas with alkenes. Furthermore, a phosphine-free cobalt-catalyzed reductive coupling of terminal alkynes with enones, affording 1,2-trans-disubstituted alkenes as the major products in a high regioisomeric ratio, is demonstrated. In the reactions, less expensive and air-stable cobalt complexes, a mild reducing agent (Zn) and a simple hydrogen source (water) were used. A possible reaction mechanism involving a cobaltacyclopentene as the key intermediate is proposed. Copyright
- Mannathan, Subramaniyan,Cheng, Chien-Hong
-
supporting information
p. 11771 - 11777
(2012/10/30)
-
- Enantioselective bromolactonization of cis-1,2-disubstituted olefinic acids using an amino-thiocarbamate catalyst
-
A facile, highly regio- and enantioselective amino-thiocarbamate-catalyzed bromolactonization of cis-1,2-disubstituted olefinic acids has been developed. The use of the enantio-enriched lactones in the synthesis of chiral synthetic intermediates is also demonstrated. 2012
- Tan, Chong Kiat,Le, Chencheng,Yeung, Ying-Yeung
-
supporting information; experimental part
p. 5793 - 5795
(2012/08/08)
-
- Bicyclic oxygen heterocycles from γ,δ-unsaturated alcohols: Synthetic targets inspired by blepharocalyxin D
-
trans-2,8-Dioxabicyclodecanes were prepared in high yield with the creation of up to three stereocenters in a single pot by the acid-mediated reaction of γ,δ-unsaturated alcohols with aldehydes (see scheme, Bn=benzyl). This versatile reaction enables the stereoselective introduction of substituents at the C3, C4, C7, and C9 positions of the bicyclic framework. Copyright
- Bunt, Adam J.,Bailey, Christopher D.,Cons, Benjamin D.,Edwards, Sophie J.,Elsworth, Jon D.,Pheko, Tshepo,Willis, Christine L.
-
supporting information; experimental part
p. 3901 - 3904
(2012/06/04)
-
- Aminothiocarbamate-catalyzed asymmetric bromolactonization of 1,2-disubstituted olefinic acids
-
An efficient and enantioselective bromolactonization of 1,2-disubstituted olefinic acids using an amino-thiocarbamate catalyst has been developed, resulting in the formation of δ-lactones containing two chiral centers with up to 99% yield, 95% ee.
- Tan, Chong Kiat,Zhou, Ling,Yeung, Ying-Yeung
-
supporting information; experimental part
p. 2738 - 2741
(2011/06/26)
-
- Highly regioselective palladium-catalysed oxidative allylic C-H carbonylation of alkenes
-
Pd-catalysed direct oxidative carbonylation of allylic C-H bonds with carbon monoxide was first described. This new procedure shows that the inherent requirement for a leaving group in the Tsuji-Trost palladium-catalysed allylic carbonylation can be lifted, which provides a new route for accessing more synthetically useful β-enoic acid esters with high regioselectivity. The Royal Society of Chemistry 2011.
- Chen, Huoji,Cai, Congbi,Liu, Xiaohang,Li, Xianwei,Jiang, Huanfeng
-
supporting information; experimental part
p. 12224 - 12226
(2011/12/14)
-
- A short enantioselective synthesis of (+)-L-733,060 via Shi epoxidation of a homoallylic carboxylate
-
A short and efficient enantioselective synthesis of (+)-L-733,060 in 92% ee via Shi epoxidation of a homoallylic carboxylate is described. Johnson-Claisen rearrangement was employed to obtain the required carbon backbone, whilst intramolecular reductive O-to-N-ring expansion of a δ-azidolactone was used in the construction of the piperidine moiety.
- Emmanuvel, Lourdusamy,Sudalai, Arumugam
-
p. 5736 - 5738
(2008/12/22)
-
- Solvent and ligand partition reaction pathways in nickel-mediated carboxylation of methylenecyclopropanes
-
Methylenecyclopropanes are carboxylated with gaseous carbon dioxide in the presence of a stoichiometric amount of a nickel complex; the reaction pathways are significantly influenced by the reaction solvent and the amine ligand. The Royal Society of Chemi
- Murakami, Masahiro,Ishida, Naoki,Miura, Tomoya
-
p. 643 - 645
(2008/02/10)
-
- Allylic alkylation with function-bearing organozinc reagents
-
The first palladium-catalysed alkylations of allylic acetates with organozinc reagents bearing functionality are reported.The reaction proceeds well from ethanoate, and propanoates, derived organozinc halides and provides a useful method for transferring these moieties to an allyl fragment.The reaction proceeds through a monophosphine complex; attempts to perform asymmetric syntheses are unsuccessful so far. - Keywords: palladium; coupling; allylic substitution
- Doucet, Henri,Brown, John M.
-
p. 995 - 1000
(2007/10/03)
-
- The Regio- and Stereoselectivities of the Reaction of Allyl Acetates and Silyl Ketene Acetals Catalyzed by Pd(0) Complexes: A New Route to Cyclopropane Derivatives
-
Pd(0) complexes of chelating phosphines catalyzed the coupling of allyl acetates and ketene silyl acetals to yield α-allylated carboxylic acid esters.Unexpectedly alkylation of the central carbon atom (C2) of the allyl groups was also observed with concomitant formation of cyclopropane derivatives.In both cases the silyl enolate attacked the allyl group from the side opposite Pd.The yield of the reaction was sensitive to the nature of the ligand coordinated with palladium.The 1,1'-bis(diphenylphosphino)ferrocene-Pd complex was the most effective catalyst.
- Carfagna, C.,Mariani, L.,Musco, A.,Sallese, G.,Santi, R.
-
p. 3924 - 3927
(2007/10/02)
-
- 4-(Phenylsulfonyl)butanoic Acid. Preparation, Dianion Generation, and Application to Four-Carbon Chain Extension
-
The bishomoenolate dianion of 4-(phenylsulfonyl)butanoic acid was investigated.It was observed the dianion could be generated in greater than 95percent yield with 200 mol percent of n-BuLi at certain concentrations.The dianion was reacted with a variety o
- Thompson, Charles M.,Frick, Jeffrey A.
-
p. 890 - 896
(2007/10/02)
-
- Organic reactions involving transition metals III. The palladium(II)-catalysed dimerization of olefinic compounds
-
The palladium(II)-catalysed dimerization of olefins has been investigated. The olefinic compounds, ethylene, propene, n-butenes, methyl acrylat, and styrene, have been successfully dimerized, and the pairs of olefinic compounds, ethylene and propene, propene and 1-butene, ethylene and cyclopentene, ethylene and methyl acrylate, ethylene and styrene, and methyl acrylate and styrene successfully codimerized, using dichlorobis(benzonitrile)palladium or palladium dichloride as catalyst. In all cases, high proportions of straight-chain dimers are formed, and olefin-isomerization is a closely associated feature of the reaction. A mechanism involving a hydridopalladium(II) compound as the catalytically active species is suggested.
- Barlow,Bryant,Haszeldine,Mackie
-
p. 215 - 226
(2007/10/12)
-