- Cascade Radical Cyclization on Alkynyl Vinylogous Carbonates for the Divergent Synthesis of Tetrasubstituted Furans and Dihydrofurans
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A single alkynyl vinylogous carbonate was elaborated to tetrasubstituted furan or dihydrofuran via a cascade inter-intramolecular radical reaction by changing the radical being added. The strategy could be used in the synthesis of polycyclic heterocycles as well as bis-furan exhibiting atropisomerism. Installation of a new furan motif on the existing one was feasible by iteration. Stannyl dihydrofuran derivative was used in Stille coupling, whereas intramolecular Friedel-Crafts acylation on the furan gave furanonaphthol.
- Gharpure, Santosh J.,Padmaja,Prasath,Shelke, Yogesh G.
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Read Online
- A boron-oxygen transborylation strategy for a catalytic midland reduction
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The enantioselective hydroboration of ketones is a textbook reaction requiring stoichiometric amounts of an enantioenriched borane, with the Midland reduction being a seminal example. Here, a turnover strategy for asymmetric catalysis, boron.oxygen transb
- Nicholson, Kieran,Dunne, Joanne,DaBell, Peter,Garcia, Alexander Beaton,Bage, Andrew D.,Docherty, Jamie H.,Hunt, Thomas A.,Langer, Thomas,Thomas, Stephen P.
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p. 2034 - 2040
(2021/02/20)
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- Iron-Catalyzed Cross-Coupling of Propargyl Ethers with Grignard Reagents for the Synthesis of Functionalized Allenes and Allenols
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Herein we disclose an iron-catalyzed cross-coupling reaction of propargyl ethers with Grignard reagents. The reaction was demonstrated to be stereospecific and allows for a facile preparation of optically active allenes via efficient chirality transfer. Various tri- and tetrasubstituted fluoroalkyl allenes can be obtained in good to excellent yields. In addition, an iron-catalyzed cross-coupling of Grignard reagents with α-alkynyl oxetanes and tetrahydrofurans is disclosed herein, which constitutes a straightforward approach towards fully substituted β- or γ-allenols, respectively.
- B?ckvall, Jan-E.,Bermejo-López, Aitor,Posevins, Daniels
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supporting information
p. 22178 - 22183
(2021/09/06)
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- Benzene-1,3,5-triyl Triformate (TFBen)-Promoted Palladium-Catalyzed Carbonylative Synthesis of 2-Oxo-2,5-dihydropyrroles from Propargyl Amines
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In this letter, we developed a palladium-catalyzed procedure for the cyclocarbonylation of propargyl amines. Benzene-1,3,5-triyl triformate (TFBen) has been explored as the CO source and also as the key promotor. Various substituted 2-oxo-dihydropyrroles were produced in a facile manner in good yields (up to 90%).
- Ying, Jun,Le, Zhengjie,Wu, Xiao-Feng
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supporting information
p. 194 - 198
(2020/01/03)
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- Catalytic Ynone-Amidine Formal [4 + 2]-Cycloaddition for the Regioselective Synthesis of Tricyclic Azepines
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A Ca(OTf)2- and self-promoted ynone-amidine atom-economic formal [4 + 2]-cycloaddition of various ynones with amidines is reported for the construction of highly functionalized tricyclic azepines. High reaction rate, ease of operation, and high product se
- Reddy, T. Prabhakar,Gujral, Jagjeet,Roy, Pritam,Ramachary, Dhevalapally B.
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supporting information
p. 9653 - 9657
(2021/01/09)
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- Photocatalytic Annulation-Alkynyl Migration Strategy for Multiple Functionalization of Dual Unactivated Alkenes
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A novel photoredox catalysis for multiple functionalization of two different types of unactivated alkenes in a single operation was reported through a conceptually new mode of annulation-alkynyl migration. A wide array of cyclopentane carboxylates were sy
- Zhao, Qi,Hao, Wen-Juan,Shi, Hao-Nan,Xu, Ting,Tu, Shu-Jiang,Jiang, Bo
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supporting information
p. 9784 - 9789
(2019/12/24)
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- Rh(III)-Catalyzed meta-C-H Alkenylation with Alkynes
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Rh(III)-catalyzed meta-C-H functionalization reactions are still rare. Herein, we report the first example of Rh(III)-catalyzed meta-C-H alkenylation with disubstituted alkynes directed by a U-shaped nitrile template. Exclusive regio-selectivity has been achieved using unsymmetrical aryl and alkyl-disubstituted alkynes to afford synthetically valuable trisubstituted olefins. Propargyl alcohols are also compatible, affording complex allylic alcohols. Notably, transition metal-catalyzed meta-alkenylation with alkynes has not been successful with Pd catalysts.
- Xu, Hua-Jin,Kang, Yan-Shang,Shi, Hang,Zhang, Ping,Chen, You-Ke,Zhang, Bing,Liu, Zhi-Qiang,Zhao, Jing,Sun, Wei-Yin,Yu, Jin-Quan,Lu, Yi
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supporting information
p. 76 - 79
(2019/01/11)
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- Transition-metal-free C-C σ-bond activation of α-aryl ketones and subsequent Zn-catalyzed intramolecular cyclization: synthesis of tetrasubstituted furans
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A highly atom-economical protocol for the synthesis of tetrasubstituted furans has been developed. This process is realized through the tandem reactions of Cs2CO3 promoted C-C σ-bond activation of α-aryl ketones followed by Zn-cataly
- Yuan, Yang,Tan, Hailu,Kong, Lingkai,Zheng, Zhong,Xu, Murong,Huang, Jiaqi,Li, Yanzhong
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p. 2725 - 2733
(2019/03/12)
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- Phosphine-Catalyzed Intermolecular Annulations of Fluorinated ortho-Aminophenones with Alkynones – The Switchable [4+2] or [4+2]/[3+2] Cycloaddition
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A phosphine-catalyzed intermolecular annulation reaction of functionalized ortho-aminoacetophenones with alkynones has been disclosed in this paper. A variety of 2-alkynylquinolines and benzo-fused indolizine were selectively afforded in moderate to good yields at different reaction temperatures and with different phosphine catalysts via the in situ generated zwitterionic intermediate derived from alkynone and phosphine. (Figure presented.).
- Zhang, Yanshun,Sun, Yaoliang,Wei, Yin,Shi, Min
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supporting information
p. 2129 - 2135
(2019/03/13)
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- Asymmetric Propargylic Radical Cyanation Enabled by Dual Organophotoredox and Copper Catalysis
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The first asymmetric propargylic radical cyanation was realized through a dual photoredox and copper catalysis. An organic photocatalyst serves to both generate propargyl radicals and oxidize Cu(I) species to Cu(II) species. A chiral Cu complex functions as an efficient organometallic catalyst to resemble the propargyl radical and cyanide in an enantio-controlled manner. Thus, a diverse range of optically active propargyl cyanides were produced with high reaction efficiency and enantioselectivities (28 examples, 57-97% yields and 83-98% ee). Moreover, mechanistic investigations including experiments and density functional theory calculations were performed to illustrate on the reaction pathway and stereochemical results.
- Lu, Fu-Dong,Liu, Dan,Zhu, Lei,Lu, Liang-Qiu,Yang, Qian,Zhou, Quan-Quan,Wei, Yi,Lan, Yu,Xiao, Wen-Jing
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supporting information
p. 6167 - 6172
(2019/04/17)
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- Palladium(II)/Lewis acid cocatalyzed oxidative annulation of 2-alkenylanilines and propargylic esters: An access to benzo[ b]azepines
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An attractive approach to valuable yet synthetically challenging benzo[b]azepines was established via palladium(II)/Lewis acid cocatalyzed oxidative [5 + 2] annulation of readily available 2-alkenylanilines and propargylic esters. The protocol features mild reaction conditions and good functional group tolerance, constituting an array of benzo[b]azepines in yields of 30-75%.
- Qiao, Hong,Zhang, Shengjun,Li, Kangkang,Cao, Zhengqiang,Zeng, Fanlong
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p. 10843 - 10851
(2019/09/12)
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- Controllable chemoselectivity in the coupling of bromoalkynes with alcohols under visible-light irradiation without additives: Synthesis of propargyl alcohols and α-ketoesters
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The chemoselectivity of visible-light-induced coupling reactions of bromoalkynes with alcohols can be controlled by simple changes to the reaction atmosphere (N2 or O2). A N2 atmosphere favours propargyl alcohols via a direct C-C coupling process, whereas an O2 atmosphere results in the generation of α-ketoesters through the oxidative CC/C-O coupling pathway.
- Ni, Ke,Meng, Ling-Guo,Ruan, Hongjie,Wang, Lei
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supporting information
p. 8438 - 8441
(2019/07/22)
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- Complementary regioselective synthesis of 3,5-disubstituted isoxazoles from ynones
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Two regioselective synthetic routes towards 3,5-disubstituted isoxazoles from ynones are reported. One route takes place via first converting the ynones to ynone O-methyl oximes, followed by a palladium-catalyzed intramolecular cyclization. The other invo
- Liu, Xiaochen,Hong, Dongsub,She, Zhigang,Hersh, William H.,Yoo, Barney,Chen, Yu
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p. 6593 - 6606
(2018/10/05)
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- Preparation method and application of xylose carbon glycoside drug
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The invention provides an xylose carbon glycoside drug. A structural formula of the compound is as follows as show in the specification, wherein Ar comprises Ph-, 3-F-Ph- or 3,5-F2-Ph-; and R comprises n-Pr-, PhCH2CH2- or i-Pr-. A preparation method of th
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Paragraph 0036
(2018/07/06)
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- Axially chiral tridentate isoquinoline derived ligands for diethylzinc addition to aldehydes
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The synthesis and resolution of new tridentate isoquinoline-derived ligands has been developed. The key steps in the synthetic sequence include successive, chemo-selective Suzuki-Miyaura cross-couplings of 1,3-dichloroisoquinoline with suitable arylboronic acids. The new ligands prepared in this manner were resolved either via molecular complexation with N-benzylcinchonidinium chloride as with 1-[3-(2-hydroxyphenyl)isoquinolin-1-yl]naphthalen-2-ol or via chromatographic separation of its epimeric camphorsulfonates as for 1,3-bis-(2-hydroxynaphthalen-1-yl)isoquinoline. 4-tert-Butyl-2-chloro-6-[1-(2-hydroxymethylnaphthalen-1-yl)isoquinolin-3-yl]phenol was resolved by chiral semi-preparative HPLC. The application of these ligands in the diethylzinc addition to aldehydes was investigated. In certain cases, the desired secondary alcohols were obtained in high yield with excellent enantiomeric excess (ee > 99%) at low catalyst loading (1 mol%).
- Sweetman, Brian A.,Guiry, Patrick J.
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p. 5567 - 5581
(2018/08/09)
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- One-Pot Synthesis of Polysubstituted Imidazoles via Sequential Staudinger/aza-Wittig/Ag(I)-Catalyzed Cyclization/Isomerization
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A new one-pot preparation of polysubstituted imidazoles by a Staudinger/aza-Wittig/Ag(I)-catalyzed cyclization/isomerization has been developed. The easily accessible propargylazide derivatives reacted with triphenylphosphine, isocyanates, and amines sequ
- Xiong, Jun,Wei, Xiao,Liu, Zi-Ming,Ding, Ming-Wu
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p. 13735 - 13739
(2017/12/26)
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- Alkynylation of aldehydes mediated by zinc and allyl bromide: a practical synthesis of propargylic alcohols
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Abstract: A practical synthesis of propargylic alcohols was developed by alkynylation of aldehydes mediated by zinc and allyl bromide. Aromatic, aliphatic and vinyl aldehydes react with phenylacetylene or 1-hexyne to obtain various propargylic alcohols at room temperature in up to 98% yield. This method is characterized with inexpensive materials, wide substrate scope, and mild reaction conditions, and is also easy to scale up. In addition, this protocol is applicable to the alkynylation of α-ketone esters and epoxides to generate α-tertiary-hydroxy esters and α-alkynyl alcohols, respectively. Graphical Abstract: [Figure not available: see fulltext.].
- Zhou, Ji-Cai,Zhao, Lei,Li, Yuan,Fu, Ding-Qiang,Li, Zi-Cheng,Huang, Wen-Cai
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p. 4283 - 4294
(2017/06/20)
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- On the Distribution of Linear versus Angular Naphthalenes in Aromatic Tetradehydro-Diels–Alder Reactions – Effect of Linker Structure and Steric Bulk
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We report here a systematic study of the aromatic tetradehydro-Diels–Alder (Ar-TDDA) reaction to elucidate the factors that have significant effects on the distribution of linear and angular naphthalene products. Two factors were studied, that is, the nat
- Chinta, Bhavani Shankar,Baire, Beeraiah
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supporting information
p. 3381 - 3385
(2017/06/29)
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- Ruthenium-Catalyzed Asymmetric Transfer Hydrogenation of Propargylic Ketones
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The asymmetric transfer hydrogenation of α,β-propargyl ketones catalyzed by an in situ formed ruthenium-hydroxyamide complex was explored. The acetylenic alcohols were isolated in good to excellent yields with excellent ee values (typically >90 %) after s
- Shatskiy, Andrey,Kivij?rvi, Tove,Lundberg, Helena,Tinnis, Fredrik,Adolfsson, Hans
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p. 3818 - 3821
(2016/01/25)
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- Synthesis of quinazoline based chiral ligands and application in the enantioselective addition of phenylacetylene to aldehydes
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Five novel 4-phenylquinazolinols were synthesised in three steps. Their application as ligands in the titanium tetraisopropoxide promoted catalytic enantioselective addition of phenylacetylene to a variety of aldehydes gave propargylic alcohols. Under the
- Karakaya, Idris,Karabuga, Semistan,Altundas, Ramazan,Ulukanli, Sabri
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supporting information
p. 8385 - 8388
(2015/03/05)
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- Methyltrichlorosilane as an effective activation agent for swern oxidation
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A practical and efficient alternative version of the Swern oxidation has been successfully developed. Methyltrichlorosilane was used as an efficient activator of dimethylsulfoxide, which could oxidize a wide range of primary and secondary alcohols to the corresponding carbonyl compounds with good to excellent yields.
- Wang, Yuanxun,Wang, Chao,Sun, Jian
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supporting information
p. 2961 - 2965
(2014/10/15)
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- Utilization of whole cell mediated deracemization in a chemoenzymatic synthesis of enantiomerically enriched polycyclic chromeno[4,3-b] pyrrolidines
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Various aryl and alkyl substituted optically pure propargyl alcohols were obtained with excellent ee (up to >99%) and isolated yields (up to 87%) by deracemization using whole cells of Candida parapsilosis ATCC 7330. The whole cells show substrate specificity towards alkyl substituted propargyl alcohols and a switch in the enantioselectivity has been observed from 'R' to 'S' upon increasing the chain length. For the first time, enantiopure (R)-4-(3-hydroxybut-1-ynyl)benzonitrile, (R)-4-(biphenyl-4-yl)but-3-yn-2-ol, (S)-ethyl 3-hydroxy-5-phenylpent-4-ynoate and (S)-4-phenylbut-3-yne-1,2-diol were obtained using this strategy. Optically pure propargyl alcohol thus obtained was used as a chiral starting material in the synthesis of enantiomerically enriched poly-substituted pyrrolidines and a pyrrole derivative successfully demonstrating a chemoenzymatic route. This journal is
- Saravanan, Thangavelu,Jana, Sushital,Chadha, Anju
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supporting information
p. 4682 - 4690
(2014/06/24)
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- Iridium-catalyzed [2+2+2] cycloaddition of α,ω-diynes with alkynyl ketones and alkynyl esters
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We found that the combination of [Ir(cod)Cl]2 and rac-BINAP served as an efficient catalyst for the [2+2+2] cycloaddition of 2,7-nonadiyne derivatives and related compounds with alkynyl ketones and alkynyl esters. The corresponding products wer
- Hashimoto, Toru,Okabe, Arisa,Mizuno, Takeshi,Izawa, Mao,Takeuchi, Ryo
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supporting information
p. 8681 - 8689
(2015/01/09)
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- Synthesis of substituted 3-hydroxy-2-furanone derivatives via an unusual enolate wittig rearrangement/alkylative cyclization sequence
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Treatment of methyl O-(alkynylmethyl) glycolate derivatives with dialkylboron triflates and Huenig's base leads to the formation of highly substituted 3-hydroxy-2-furanone derivatives. The transformations appear to proceed via an unusual mechanism involving initial 2,3-Wittig rearrangement of a boron ester enolate followed by an alkylative cyclization reaction that leads to incorporation of an alkyl group from the boron reagent into the product.
- Everett, Renata K.,Wolfe, John P.
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supporting information
p. 2926 - 2929
(2013/07/26)
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- Kinetic resolution of propargylamines via a highly enantioselective non-enzymatic N-acylation process
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The non-enzymatic kinetic resolution of diversely substituted primary propargylic amines is reported featuring a highly selective acetyl transfer using (1S,2S)-1 in conjunction with AliquatTM 336, affording the corresponding enantio-enriched N-
- Kolleth, Amandine,Christoph, Sarah,Arseniyadis, Stellios,Cossy, Janine
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supporting information
p. 10511 - 10513,3
(2020/09/02)
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- METHOD FOR PRODUCING ARYL, HETEROARYL, OR ALKENYL-SUBSTITUTED UNSATURATED HYDROCARBON
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The present invention relates to a method for producing aryl-, heteroaryl- or alkenyl-substituted unsaturated hydrocarbons, containing: reacting aryl halides, heteroaryl halides or alkenyl halides with alkynes or alkenes in the presence of a palladium catalyst to obtain a crude product, and subsequently distillatively purifying the crude product in the presence of a compound having at least one NC═S group.
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Page/Page column 5
(2012/06/16)
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- Solvent-free synthesis of propargylic alcohols using zno as a new and reusable catalyst by direct addition of alkynes to aldehydes
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Under solvent-free conditions, the synthesis of propargylic alcohols by direct addition of terminal alkynes to aldehydes promoted by ZnO as a novel, commercially, and cheap catalyst is described. Furthermore, the catalyst can be reused for several times w
- Hosseini-Sarvari, Mona,Mardaneh, Zahra
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experimental part
p. 4297 - 4303
(2012/02/16)
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- PtI2-Catalyzed tandem 3,3-rearrangement/Nazarov reaction of arylpropargylic esters: Synthesis of indanone derivatives
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An efficient PtI2-catalyzed tandem reaction of arylpropargylic esters, involving 3,3-rearrangement and Nazarov reaction, has been developed to produce 3-substituted and 3,3-disubstituted indanone derivatives. This approach provided a pathway to the synthesis of indanone skeletons in natural products.
- Zheng, Huaiji,Xie, Xingang,Yang, Juan,Zhao, Changgui,Jing, Peng,Fang, Bowen,She, Xuegong
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experimental part
p. 7755 - 7762
(2011/12/03)
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- Switching of enantioselectivity in the catalytic addition of diethylzinc to aldehydes by regioisomeric chiral 1,3-amino sulfonamide ligands
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Twenty chiral 1,3-amino sulfonamides of two classes (2a-i and 3a-k) have been prepared from (-)-cis-2-benzamidocyclohexanecarboxylic acid (1) and studied as ligands for catalytic enantioselective addition of Et2Zn to a variety of aromatic and aliphatic aldehydes. The ligands 2 and 3 are regioisomers in which the position of the amine and sulfonamide groups is exchanged. Each class of ligands with the same chirality was shown to afford sec-alcohols with the opposite stereochemistry. Structural surveys revealed that the combination of tertiary amino and p-toluenesufonylamido groups works most effectively for the reaction. Through optimization of the structural and reaction conditions, the best ligands quantitatively provided both enantiomeric secondary alcohols in good to excellent enantioselectivity of up to 94% and 98% ee for (S)- and (R)-enantiomers, respectively.
- Hirose, Takuji,Sugawara, Kazuyuki,Kodama, Koichi
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experimental part
p. 5413 - 5428
(2011/08/05)
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- Palladium-catalyzed coupling of propargylic carbonates with N-tosylhydrazones: Highly selective synthesis of substituted propargylic N-sulfonylhydrazones and vinylallenes
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An efficient palladium-catalyzed coupling of propargylic carbonates (1) with N-tosylhydrazones (2, 2′) has been carried out. A wide range of propargylic N-sulfonylhydrazones (3) and multisubstituted vinylallenes (4) can be obtained selectively by using either [PdCl2(CH3CN) 2] or [Pd2(dba)3] as catalysts. (dba=trans,trans-dibenzylideneacetone, dppp=propane-l,3- diylbis(diphenylphosphane), Ts=4-toluenesulfonyl.) Copyright
- Chen, Zi-Sheng,Duan, Xin-Hua,Wu, Lu-Yong,Ali, Shaukat,Ji, Ke-Gong,Zhou, Ping-Xin,Liu, Xue-Yuan,Liang, Yong-Min
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p. 6918 - 6921
(2011/07/08)
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- SUBSTITUTED OXADIAZOLE DERIVATIVES AS S1P AGONISTS IN THE TREATMENT OF AUTOIMMUNE AND INFLAMMATORY DISEASES
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Disclosed are compounds of Formula (I) [INSERT CHEMICAL STRUCTURE HERE] (I) or pharmaceutically acceptable salts thereof, wherein Q is [INSERT CHEMICAL STRUCTURE HERE] or [INSERT CHEMICAL STRUCTURE HERE]; R1 is alkyl or aryl, said aryl optionally substituted with one to five substituents independently selected from C1 to C6 alkyl, C1 to C4 haloalkyl, OR4, and/or halogen; and R2, R3, R4, and n are defined herein. Also disclosed are methods of using such compounds as selective agonists for G protein-coupled receptor S1P1, and pharmaceutical compositions comprising such compounds. These compounds are useful in treating, preventing, or slowing the progression of diseases or disorders in a variety of therapeutic areas, such as autoimmune diseases and vascular disease.
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Page/Page column 86
(2010/08/08)
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- The synthesis of new oxazoline-containing bifunctional catalysts and their application in the addition of diethylzinc to aldehydes
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The straightforward preparation of new modular oxazoline-containing bifunctional catalysts is reported employing a microwave-assisted Buchwald-Hartwig aryl amination as the key step. Covalent attachment of 2-(o-aminophenyl)oxazolines and pyridine derivati
- Coeffard, Vincent,Mueller-Bunz, Helge,Guiry, Patrick J.
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experimental part
p. 1723 - 1734
(2009/06/27)
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- Nickel-catalyzed asymmetric cross-couplings of racemic propargylic halides with arylzinc reagents
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A stereoconvergent method for the catalytic asymmetric Negishi cross-coupling of racemic secondary propargylic halides with arylzinc reagents has been developed. Neither family of compounds has previously been shown to be a suitable partner in such coupling processes. From a practical point of view, it is noteworthy that the catalyst components (NiCl2·glyme and pybox ligand 1) are commercially available. Copyright
- Smith, Sean W.,Fu, Gregory C.
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supporting information; experimental part
p. 12645 - 12647
(2009/05/09)
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- Asymmetric addition of phenylacetylene to aldehydes catalyzed by soluble optically active polybinaphthols ligand
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A chiral polymer ligand was synthesized by the polymerization of (S)-5,5′-dibromo-6,6′-dibutyl-2,2′-binaphthol (S-M-1) with (S)-2,2′-bishexyloxy-1,1′-binaphthyl-6,6′-boronic acid (S-M-2) via Pd-catalyzed Suzuki reaction. The application of the chiral poly
- Wu, Linglin,Zheng, Lifei,Zong, Lili,Xu, Jinqian,Cheng, Yixiang
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p. 2651 - 2657
(2008/09/19)
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- The first enantioselective addition of diethylzinc to aldehydes in ionic liquids catalysed by a recyclable ion-tagged diphenylprolinol
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The new procedure for the asymmetric addition of diethylzinc to aryl aldehydes in room-temperature ionic liquids (RTILs) was developed, in the field of chemical synthesis and catalysis. The use of tailored catalysts for metathesis, cross coupling and hydroformylation reactions in RTILs was also explored. A solution of diethylzinc was added to a solution of catalyst 1d and the mixture was stirred at RT for 5 min. The reaction was quenched with a few drops of water and resulting mixture was directly on the top of a silica gel column diluting with CH2Cl2. The results showed that the diphenylprolinol-derived 1d is a promising candidate to accelerate the asymmetric addition of diethylzinc to aromatic aldehydes. This also showed that operation is simple and efficient and is easily recyclable, making use of 10 mol% loading of 1d.
- Lombardo, Marco,Chiarucci, Michel,Trombini, Claudio
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scheme or table
p. 11288 - 11291
(2009/10/23)
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- Synthesis of camphorsulfonamide-based quinoline ligands and their N-oxides: first use in the enantioselective addition of organozinc reagents to aldehydes
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The preparation of several camphorsulfonamide-based quinoline derivatives and their N-oxides was accomplished via an indirect Friedlaender synthesis using aminobenzylic alcohols and RuCl2(DMSO)4 as a catalyst. These ligands were tested in the enantioselective addition of dialkylzinc reagents to aldehydes, with enantiomeric excesses up to 96%. A similar protocol using triphenylborane and diethylzinc gave the corresponding phenylation process.
- Martinez, Ricardo,Zoli, Luca,Cozzi, Pier Giorgio,Ramon, Diego J.,Yus, Miguel
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experimental part
p. 2600 - 2607
(2009/04/11)
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- Cationic rhodium(I)/bisphosphane complex-catalyzed isomerization of secondary propargylic alcohols to α,β-enones
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We have determined that hydrogenated cationic Rh(I)/bisphosphane complexes are highly active catalysts for the isomerization of secondary propargylic alcohols to α,β-enones. A kinetic resolution of secondary propargylic alcohols proceeded with moderate selectivity with [Rh((R)-BINA-P)]OTf as a catalyst. Mechanistic studies revealed that the isomerization proceeds through intramolecular 1,3- and 1,2-hydrogen migration pathways. The isomerization of propargylic diol derivatives was also investigated, which revealed that 1,4-diketones, furans, and α,β-enones were obtained from 2-butyn-1,4-diol, 1-methoxy-2-butyn-4-ol, and 1-acetoxy-2-butyn-4-ol derivatives, respectively. Furthermore, chemoselectivity of the isomerization of an acetylenic diol was investigated, and preferential oxidation of a propargylic hydroxy group was observed. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Tanaka, Ken,Shoji, Takeaki,Hirano, Masao
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p. 2687 - 2699
(2008/02/08)
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- Kinetic resolution of propargylic alcohols catalyzed by benzotetramisole
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(Chemical Equation Presented) Kinetic resolution of variously substituted secondary propargylic alcohols catalyzed by benzotetramisole (BTM) proceeds with selectivity factors up to 32, the highest ever achieved with nonenzymatic catalysts for this class o
- Birman, Vladimir B.,Guo, Lei
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p. 4859 - 4861
(2007/10/03)
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- 3,3′-diphosphoryl-1,1′-bi-2-naphthol-Zn(II) complexes as conjugate acid-base catalysts for enantioselective dialkylzinc addition to aldehydes
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A highly enantioselective dialkylzine (R22Zn) addition to a series of aromatic, aliphatic, and heteroaromatic aldehydes (5) was developed based on conjugate Lewis acid-Lewis base catalysis. Bifunctional BINOL ligands bearing phosphine oxides [P(=O)R2] (7), phosphonates [P(=O)(OR)2] (8 and 9), or phosphoramides [P(=O)(NR2) 2] (10) at the 3,3′-positions were prepared by using a phospho-Fries rearrangement as a key step. The coordination of a NaphO-Zn(II)-R2 center as a Lewis acid to a carbonyl group in a substrate and the activation of R22Zn(II) with a phosphoryl group (P=O) as a Lewis base in the 3,3′-diphosphoryl-BINOL- Zn(II) catalyst could promote carbon-carbon bond formation with high enantioselectivities (up to >99% ee). Mechanistic studies were performed by X-ray analyses of a free ligand (7) and a tetranuclear Zn(II) cluster (21), a 31P NMR experiment on Zn(II) complexes, an absence of nonlinear effect between the ligand (7) and Et-adduct of benzaldehyde, and stoichiometric reactions with some chiral or achiral Zn(II) complexes to propose a transition-state assembly including monomeric active intermediates.
- Hatano, Manabu,Miyamoto, Takashi,Ishihara, Kazuaki
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p. 6474 - 6484
(2007/10/03)
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- New chiral Schiff base as a tridentate ligand for catalytic enantioselective addition of diethylzinc to aldehydes
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We have developed new chiral Schiff base catalysts for the enantioselective addition of diethylzinc reagents to aldehydes. The reaction of benzaldehyde with diethylzinc in the presence of 1 mol % of the chiral Schiff base catalyst proceeded to afford 1-phenyl-1-propanol in 96% enantiomeric excess (ee).
- Tanaka, Takanori,Yasuda, Yorinobu,Hayashi, Masahiko
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p. 7091 - 7093
(2007/10/03)
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- Enantioselective dialkylzinc addition to aldehydes catalyzed by chiral Zn(II)-BINOLates bearing phosphonates and phosphoramides in the 3,3′-positions
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Highly enantioselective dialkylzinc addition to a series of aldehydes was developed based on chiral Zn(II)-BINOLate catalysts bearing phosphonates [P(=O)(OR)2] and phosphoramides [P(=O)(NMe2)2] at the 3,3′-positions. The reactions proceeded smoothly and showed reductions in the amounts of both catalysts and dialkylzinc reagents to be loaded. Georg Thieme Verlag Stuttgart.
- Hatano, Manabu,Miyamoto, Takashi,Ishihara, Kazuaki
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p. 1762 - 1764
(2008/02/03)
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- Cationic rhodium(I)/BINAP complex-catalyzed isomerization of secondary propargylic alcohols to α,β-enones
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(Chemical Equation Presented) We have developed a cationic rhodium(I)/BINAP complex-catalyzed isomerization of secondary propargylic alcohols to α,β-enones. The asymmetric variant of this reaction, a kinetic resolution of secondary propargylic alcohols, was also developed with good selectivity. The mechanistic study revealed that the isomerization proceeds through intramolecular 1,3- and 1,2-hydrogen migration pathways.
- Tanaka, Ken,Shoji, Takeaki
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p. 3561 - 3563
(2007/10/03)
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- Enantioselective addition of organozinc reagents to aldehydes catalyzed by 3,3′-bis(diphenylphosphinoyl)-BINOL
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The enantioselective addition of organozinc reagents to aromatic and aliphatic aldehydes 1 gives secondary alcohols 2 with excellent enantioselectivities in high yields through the catalytic use of (R)-3,3′-bis(diphenylphosphinoyl)-BINOL (3) or (R)-3,3′- bis(diphenylthiophosphinoyl)-BINOL (4) without Ti(IV) complexes. The coordination of the O or S atom of a (thio)phosphinoyl group bearing a BINOL backbone to organozinc reagents can efficiently increase the nucleophilicity of the organozinc reagents.
- Hatano, Manabu,Miyamoto, Takashi,Ishihara, Kazuaki
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p. 1561 - 1568
(2007/10/03)
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- Highly Enantioselective Additions of Diethylzinc to Aldehydes Using 2-Triflamido-methyl-2′-hydroxy-1 ,1′-binaphthyl
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(Equation presented) A new N-triflated amino alcohol-titanium catalyst was designed for the asymmetric ethylation of aldehydes. This binaphthyl-based sulfonamido alcohol ligand shows uniformly high yield and enantioselectivity in the diethylzinc additions
- Kang, Seung-Wan,Ko, Dong-Hyun,Kim, Kyoung Hoon,Ha, Deok-Chan
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p. 4517 - 4519
(2007/10/03)
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- Highly enantioselective phenylacetylene additions to both aliphatic and aromatic aldehydes.
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The readily available and inexpensive BINOL in combination with Ti(O(i)Pr)(4) is found to catalyze the reaction of an alkynylzinc reagent with various types of aldehydes including aliphatic aldehydes, aromatic aldehydes, and other alpha,beta-unsaturated a
- Gao,Moore, David,Xie, Ru-Gang,Pu, Lin
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p. 4143 - 4146
(2007/10/03)
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- Designing new chiral ketone catalysts. Asymmetric epoxidation of cis-olefins and terminal olefins
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This paper describes a new class of chiral oxazolidinone ketone catalyst for asymmetric epoxidation. High ee values have been obtained for a number of cyclic and acyclic cis-olefins. The epoxidation was stereospecific with no isomerization observed in the epoxidation of acyclic systems. Encouragingly high ee values have also been obtained for a number of terminal olefins. Mechanistic studies show that electronic interactions play an important role in stereodifferentiation.
- Tian, Hongqi,She, Xuegong,Yu, Hongwu,Shu, Lianhe,Shi, Yian
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p. 2435 - 2446
(2007/10/03)
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- Enantioselective additions of diethylzinc and diphenylzinc to aldehydes using 2-dialkyl-aminomethyl-2′-hydroxy-1,1′-binaphthyls
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(graph presented) A set of 2-dialkylaminomethyl-2′-hydroxy-1,1′-binaphthyls was prepared and used in the catalytic asymmetric additions of diethylzinc and diphenylzinc to various types of aldehydes. These binaphthyl-based axially chiral amino alcohols show high enantioselectivity in the addition of organozincs to aromatic and aliphatic aldehydes.
- Ko, Dong-Hyun,Kim, Kyoung Hoon,Ha, Deok-Chan
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p. 3759 - 3762
(2007/10/03)
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- Synthesis of C2-symmetrical bis(1,2-hydroxy sulfonamide) ligands and application in the enantioselective addition of dialkylzinc to aldehydes
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The preparation of several C2-symmetric disulfonamides derived from 1,2-amino alcohols and disulfonyl derivatives, as well as their use in the titanium tetraisopropoxide-promoted enantioselective additions of dialkylzinc to aldehydes are described. The enantiomeric ratio is up to 96:4, the best results being obtained for aromatic aldehydes with electron-donating groups in the para-position. There are some differences in the enantioselectivity depending on the relative positioning of the amino alcohol moieties in the chiral ligand, the 1,3-disulfonyl derivative being the best system. In the case of para-substituted benzaldehyde derivatives, a negative relationship between the electron-withdrawing character of the para-substituted group and the enantioselectivity of the addition was seen, whereas the more electronic-donating character the substituent has, the higher the observed enantioselectivity.
- Yus, Miguel,Ramon, Diego J.,Prieto, Oscar
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p. 1573 - 1579
(2007/10/03)
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