- Copper-Catalyzed Regio- And Enantioselective Hydroallylation of 1-Trifluoromethylalkenes: Effect of Crown Ether
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A Cu-catalyzed regio- and enantioselective hydroallylation of 1-trifluoromethylalkenes with hydrosilanes and allylic chlorides has been developed. Anin situgenerated CuH species undergoes the hydrocupration regio- and enantioselectively to form a chiral α-CF3alkylcopper intermediate, which then leads to the optically active hydroallylated product. The key to success is the use of not only an appropriate chiral bisphosphine ligand but also 18-crown-6 to suppress the otherwise predominant β-F elimination from the α-CF3alkylcopper intermediate. The asymmetric Cu catalysis successfully constructs the nonbenzylic and nonallylic CF3-substituted Csp3chiral center, which is difficult to operate by other means.
- Kojima, Yuki,Miura, Masahiro,Hirano, Koji
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p. 11663 - 11670
(2021/09/28)
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- A Copper(I)-Catalyzed Radical-Relay Reaction Enabling the Intermolecular 1,2-Alkylborylation of Unactivated Olefins
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The first catalytic intermolecular 1,2-alkylborylation reaction via a radical-relay mechanism between unactivated olefins, bis(pinacolato)diboron, and an alkyl electrophile is reported. Successful implementation of this method requires that the competing boryl substitution of the alkyl electrophile is retarded to facilitate the radical relay. This challenge was overcome using electronically or sterically demanding alkyl electrophiles, which results in the simultaneous and highly regioselective introduction of a gem-difluoro, monofluoro, tertiary, or secondary alkyl group and a boryl group across the C=C double bond.
- Akiyama, Sota,Oyama, Natsuki,Endo, Tsubura,Kubota, Koji,Ito, Hajime
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p. 5260 - 5268
(2021/05/04)
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- High-selectivity silane-based olefin and preparation method thereof
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The invention provides high-selectivity silane-based olefin and a preparation method thereof. The preparation method comprises the following steps that an iron catalyst, a ligand and sodium tert-butoxide are subjected to nitrogen extraction and gas exchange twice under the sealed condition, so that a mixed raw material is obtained; then, aliphatic gem-difluoroolefin, triethyl(4,4,5,5-tetramethyl-1,3,2-dioxaboridine-2-yl)silane and an organic solvent are added to form a reactant; and after quenching, extraction, drying, filtration, vacuum concentration and purification are successively carriedout to obtain the high-selectivity silyl olefin. The invention also provides the high-selectivity silane-based olefin prepared by the method. According to the invention, iron catalysis is used for selective silanization of non-activated aliphatic gem-difluoroolefin, gem-disilyl olefin with controllable regioselectivity and stereoselectivity and silylated fluoroolefin with controllable Z/E selectivity are efficiently synthesized, and the problems of low regioselectivity and stereoselectivity and difficult conversion are effectively solved.
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Paragraph 0032; 0037
(2020/06/02)
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- Design and Synthesis of TY-Phos and Application in Palladium-Catalyzed Enantioselective Fluoroarylation of gem-Difluoroalkenes
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The first example of highly enantioselective fluoroarylation of gem-difluoroalkenes with aryl halides is presented by using a new chiral sulfinamide phosphine (Sadphos) type ligand TY-Phos. N-Me-TY-Phos can be easily synthesized on a gram scale from readily available starting materials in three steps. Salient features of this work including readily available starting materials, good yields, high enantioselectivities as well as broad substrate scope make this approach very practical and attractive. Notably, the asymmetric synthesis of an analogue of a biologically active molecule is also reported.
- Li, Zhiming,Lin, Tao-Yan,Liu, Yu,Pan, Zhangjin,Tu, Youshao,Wu, Hai-Hong,Zhang, Junliang,Zhu, Shuai
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supporting information
p. 22957 - 22962
(2020/10/19)
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- Coupling of Trifluoroacetaldehyde N-Triftosylhydrazone with Organoboronic Acids for the Synthesis of gem-Difluoroalkenes
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The synthesis of alkyl gem-difluoroalkenes remains a difficult task in organic synthesis. Here, we report a general and efficient approach for tackling this problem by gem-difluoroolefination of trifluoroacetaldehyde N-triftosylhydrazone with organoboronic acids. This protocol is operationally simple, free of transition metals, and suitable for a broad range of organoboronic acids. Moreover, the utility of the products was demonstrated by further conversion of the gem-difluorovinyl group.
- Ma, Yu,Reddy, Bhoomireddy Rajendra Prasad,Bi, Xihe
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p. 9860 - 9863
(2019/12/24)
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- Synthesis of α-Trifluoromethylamines by Cu-Catalyzed Regio- and Enantioselective Hydroamination of 1-Trifluoromethylalkenes
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A copper-catalyzed regioselective net hydroamination of 1-trifluoromethylalkenes with hydrosilanes and hydroxylamines has been developed. The judicious choice of ligand and additive suppresses the conceivable but undesired β-F elimination of an α-CF3
- Takata, Tatsuaki,Hirano, Koji,Miura, Masahiro
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supporting information
(2019/06/13)
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- Nickel-Catalyzed Difluoroalkylation of (Hetero)Arylborons with Unactivated 1-Bromo-1,1-difluoroalkanes
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A nickel-catalyzed cross-coupling between (hetero)arylborons and unactivated 1-bromo-1,1-difluoroalkanes has been developed. The use of two ligands (a bidentate bipyridine-based ligand, 4,4′-ditBu-bpy, and a monodentate pyridine-based ligand, DMAP) offers a highly efficient nickel-based catalytic system to prepare difluoroalkylated arenes which have important applications in medicinal chemistry. Ligand combo: The title reaction requires the use of a combined (2+1) ligand system, that is, a combination of a bi- and monodentate ligand (4,4′-ditBu-bpy + DMAP). This system allows employment of a wide range of unactivated 1-bromo-1,1-difluoroalkanes as coupling partners, thus providing a highly efficient method for applications in drug discovery and development. bpy=bipyridine, DMAP=4-(N,N-dimethylamino)pyridine.
- Xiao, Yu-Lan,Min, Qiao-Qiao,Xu, Chang,Wang, Ruo-Wen,Zhang, Xingang
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supporting information
p. 5837 - 5841
(2016/05/09)
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- Visible light-induced selective hydrobromodifluoromethylation of alkenes with dibromodifluoromethane
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A visible light-induced selective hydrobromodifluoromethylation of alkenes using CF2Br2 was developed. This transformation proceeded smoothly in the presence of catalytic eosin Y at room temperature to give various hydrobromodifluoromethylated compounds with broad functional group tolerance.
- Lin, Qing-Yu,Xu, Xiu-Hua,Qing, Feng-Ling
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p. 8740 - 8749
(2015/08/24)
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- NUCLEOPHILIC SUBSTITUTION REACTIONS OF DIFLUOROMETHYL PHENYL SULFONE WITH ALKYL HALIDES LEADING TO THE FACILE SYNTHESIS OF TERMINAL 1,1-DIFLUORO-1-ALKENES AND DIFLUOROMETHYLALKANES
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(Benzenesulfonyl)difluoromethyl anion, in situ generated from difluoromethyl phenyl sulfone and a base, was found to easily undergo nucleophilic substitution reactions (SN2 with primary alkyl halides, elemental halogens, and perfluoroalkyl halides with good selectivity. The formed (Benzenesulfonyl) difluoromethylalkanes are useful intermediates for the facile preparation of 1,1-difluoro-1alkenes and difluoromethylalkanes. Thus, difluoromethyl phenyl sulfone acts as both “CF2=” and CF2H” synthons.
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Page/Page column 11; 18
(2008/06/13)
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- Friedel-crafts cyclization of 1,1-difluoroalk-1-enes: Synthesis of benzene-fused cyclic ketones via α-fluorocarbocations
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1,1-Difluoroalk-1-enes bearing a phenyl group at the C-3, -4, or -5 position, readily obtained from 2,2,2-trifluoroethyl p-toluenesulfonate, are treated with FSO3H·SbF5 to undergo Friedel-Crafts cyclization in (CF3)2CHOH. The cyclization takes place via α-fluorocarbocations, followed by spontaneous hydrolysis of the C-F bond to afford bicyclic ketones including a five, six, or seven-membered ring in good yield.
- Ichikawa, Junji,Jyono, Hideharu,Kudo, Takao,Fujiwara, Masaki,Yokota, Misaki
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- Difluoromethyl phenyl sulfone, a difluoromethylidene equivalent: Use in the synthesis of 1,1-difluoro-1-alkenes
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A nucleophilic substitution-elimination reaction strategy in which difluoromethyl phenyl sulfone is used as a selective difluoromethylidene equivalent allows the facile synthesis of 1,1-difluoro-1-alkenes from primary alkyl halides (see scheme).
- Prakash, G.K. Surya,Hu, Jinbo,Wang, Ying,Olah, George A.
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p. 5203 - 5206
(2007/10/03)
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- A new route to 1,1-difluoroolefins from carboxylic acids
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Methodology is described for the conversions of carboxylic acids to 1,1-difluoroolefins via α,α-difluorothioethers (3).
- Kim, Kyung-Il,McCarthy, James R.
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p. 3223 - 3226
(2007/10/03)
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