- Palladium-catalysed Reactions of Ketenes with Allyl Acetates or Allyl Carbonates: Novel Syntheses of 1,3-Dienes and Allylated Esters
-
The reaction of arylketenes with allyl acetates or allyl carbonates catalysed by tetrakis(triphenylphosphine)palladium selectively gives 1,3-dienes or allylated esters, respectively, in high yields.
- Mitsudo, Take-aki,Kadokura, Mamoru,Watanabe, Yoshihisa
-
-
Read Online
- Iodoarene-Catalyzed Oxyamination of Unactivated Alkenes to Synthesize 5-Imino-2-Tetrahydrofuranyl Methanamine Derivatives
-
Reported here is the room-temperature metal-free iodoarene-catalyzed oxyamination of unactivated alkenes. In this process, the alkenes are difunctionalized by the oxygen atom of the amide group and the nitrogen in an exogenous HNTs2 molecule. This mild and open-air reaction provided an efficient synthesis to N-bistosyl-substituted 5-imino-2-tetrahydrofuranyl methanamine derivatives, which are important motifs in drug development and biological studies. Mechanistic study based on experiments and density functional theory calculations showed that this transformation proceeds via activation of the substrate alkene by an in situ generated cationic iodonium(III) intermediate, which is subsequently attacked by an oxygen atom (instead of nitrogen) of amides to form a five-membered ring intermediate. Finally, this intermediate undergoes an SN2 reaction by NTs2 as the nucleophile to give the oxygen and nitrogen difunctionalized 5-imino-2-tetrahydrofuranyl methanamine product. An asymmetric variant of the present alkene oxyamination using chiral iodoarenes as catalysts also gave promising results for some of the substrates.
- Deng, Xiao-Jun,Liu, Hui-Xia,Zhang, Lu-Wen,Zhang, Guan-Yu,Yu, Zhi-Xiang,He, Wei
-
p. 235 - 253
(2021/01/09)
-
- Asymmetric Intramolecular Hydroalkoxylation of Unactivated Alkenes Catalyzed by Chiral N-Triflyl Phosphoramide and TiCl4?
-
By using a combination of a chiral N-triflyl phosphoramide and TiCl4 as the catalyst, a new process for asymmetric intramolecular hydroalkoxylation of unactivated alkenes was developed, producing various chiral tetrahydrofuran derivatives in 51%—99% yields with 30%—71% ee's.
- Cheng, Aolin,Li, Yingkun,Ma, Jiguo,Wang, Xinxu,Zhang, Yi,Zhao, Baoguo,Zhao, Guoqing,Zhao, Pengyuan
-
p. 565 - 569
(2020/04/23)
-
- mCPBA-mediated dioxygenation of unactivated alkenes for the synthesis of 5-imino-2-tetrahydrofuranyl methanol derivatives
-
A mCPBA-mediated, metal-free, intramolecular dioxygenation reaction of unactivated alkenes is reported. In the presence of m-chlorobenzoic peracid, different unsaturated amide substrates could be cyclized via epoxide intermediates, producing the corresponding 5-imino-2-tetrahydrofuranyl methanol products in up to 94% yield at room temperature.
- Deng, Xiaojun,Zhang, Luwen,Liu, Huixia,Bai, Yu,He, Wei
-
-
- Copper-Catalyzed Modular Amino Oxygenation of Alkenes: Access to Diverse 1,2-Amino Oxygen-Containing Skeletons
-
Copper-catalyzed alkene amino oxygenation reactions using O-acylhydroxylamines have been achieved for a rapid and modular access to diverse 1,2-amino oxygen-containing molecules. This transformation is applicable to the use of alcohols, carbonyls, oximes, and thio-carboxylic acids as nucleophiles on both terminal and internal alkenes. Mild reaction conditions tolerate a wide range of functional groups, including ether, ester, amide, carbamate, and halide. The reaction protocol allows for starting with free amines as the precursor of O-benzoylhydroxylamines to eliminate their isolation and purification, contributing to broader synthetic utilities. Mechanistic investigations reveal the amino oxygenation reactions may involve distinct pathways, depending on different oxygen nucleophiles.
- Hemric, Brett N.,Chen, Andy W.,Wang, Qiu
-
p. 1468 - 1488
(2019/01/25)
-
- Niobium-Catalyzed Intramolecular Addition of O-H and N-H Bonds to Alkenes: A Tool for Hydrofunctionalization
-
A convenient, versatile, and easy to handle intramolecular hydrofunctionalization of alkenes (C-O and C-N bonds formation) is reported using a novel niobium-based catalytic system. This atom economic and eco-friendly methodology provides an additional synthetic tool for the straightforward formation of valuable building blocks enabling molecular complexity. Various pyran, furan, pyrrolidine, piperidine, lactone, and lactam derivatives as well as spirocyclic compounds are produced in high yields and selectivities.
- Ferrand, Laura,Tang, Yue,Aubert, Corinne,Fensterbank, Louis,Mouriès-Mansuy, Virginie,Petit, Marc,Amatore, Muriel
-
supporting information
p. 2062 - 2065
(2017/04/28)
-
- Isomerization of olefins triggered by rhodium-catalyzed C-H bond activation: Control of endocyclic β-hydrogen elimination
-
Five-membered metallacycles are typically reluctant to undergo endocyclic β-hydrogen elimination. The rhodium-catalyzed isomerization of 4-pentenals into 3-pentenals occurs through this elementary step and cleavage of two C-H bonds, as supported by deuterium-labeling studies. The reaction proceeds without decarbonylation, leads to trans olefins exclusively, and tolerates other olefins normally prone to isomerization. Endocyclic β-hydrogen elimination can also be controlled in an enantiodivergent reaction on a racemic mixture.
- Yip, Stephanie Y. Y.,A?ssa, Christophe
-
supporting information
p. 6870 - 6873
(2015/06/02)
-
- Intramolecular Hydroalkoxylation of Unactivated Alkenes Using Silane-Iodine Catalytic System
-
A novel catalytic system using I2 and PhSiH3 for the intramolecular hydroalkoxylation of unactivated alkenes is described. NMR study indicated that in situ generated PhSiH2I is a possible active catalytic species. This catalytic system allows an efficient intramolecular hydroalkoxylation of phenyl-, trialkyl-, and 1,1-dialkyl-substituted alkenes as well as a variety of unactivated monoalkyl- and 1,2-dialkyl-substituted alkenes at room temperature. Mechanistic consideration based on significant experimental observations is also discussed.
- Fujita, Shoji,Abe, Masanori,Shibuya, Masatoshi,Yamamoto, Yoshihiko
-
supporting information
p. 3822 - 3825
(2015/08/18)
-
- Intramolecular hydroalkoxylation in Bronsted acidic ionic liquids and its application to the synthesis of (±)-centrolobine
-
The SO3H-tethered imidazolium and triazolium salts, nonvolatile and recyclable Bronsted acidic ionic liquids, efficiently mediate intramolecular hydroalkoxylations of alkenyl alcohols. They have been successfully employed in the synthesis of (±)-centrolobine.
- Jeong, Yunkyung,Kim, Do-Young,Choi, Yunsil,Ryu, Jae-Sang
-
supporting information; experimental part
p. 374 - 378
(2011/02/28)
-
- Multicatalytic synthesis of complex tetrahydrofurans involving bismuth(iii) triflate catalyzed intramolecular hydroalkoxylation of unactivated olefins
-
A multicatalytic synthesis of complex tetrahydrofurans has been developed involving a Bi(OTf)3-catalyzed nucleophilic addition/ hydroalkoxylation sequence. Complex tetrahydrofuranyl products may be formed rapidly in high yield and with good diastereoselectivity. The demonstrated scope of hydroalkoxylation has also been expanded to include substrates bearing useful functional handles including carboxylate ester, olefin, nitrile, and nitro groups.
- Kelly, Brendan D.,Allen, Julia M.,Tundel, Rachel E.,Lambert, Tristan H.
-
supporting information; experimental part
p. 1381 - 1383
(2009/10/02)
-
- Palladium-Complex-Catalyzed Reactions of Ketenes with Allylic Carbonates or Acetates. Novel Syntheses of α-Allylated Carboxylic Esters and 1,3-Dienes
-
Diphenylketene and ethylphenylketene react with allylic carbonates or acetates in the presence of a catalytic amount of tetrakis(triphenylphosphine)palladium to give α-allylated esters or 1,3-dienes, respectively.For example, the reaction of diphenylketene with allyl methyl carbonate in DMF at 0 deg C gave methyl 2,2-diphenyl-4-pentenoate in 67percent yield.The reaction of diphenylketene with allyl acetate in benzene at 25 deg C gave 1,1-diphenyl-1,3-butadiene in 72percent yield.Marked solvent effects were observed.
- Mitsudo, Take-aki,Kadokura, Mamoru,Watanabe, Yoshihisa
-
p. 1695 - 1699
(2007/10/02)
-