- Palladium-catalyzed allylic C-H oxidation under simple operation and mild conditions
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We discovered an effective and simple system (Pd/BQ/air/r.t.) for making allylic alcohols through Pd-catalyzed allylic C-H bond functionalization. This approach exhibits advantages due to its simple operation, mild conditions, and environmentally benign features. By modifying reaction conditions, it can be suitable for preparing unsaturated aldehydes, allylic esters, ethers, and amines.
- Guo, Yunlong,Shen, Zengming
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- Copper-Catalyzed Enantiotopic-Group-Selective Allylation of gem-Diborylalkanes
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We report a copper-catalyzed enatiotopic-group-selective allylation of gem-diborylalkanes with allyl bromides. The combination of copper(I) bromide and H8-BINOL derived phosphoramidite ligand proved to be the most effective catalytic system to provide various enantioenriched homoallylic boronate esters, containing a boron-substituted stereogenic center that is solely derived from gem-diborylalkanes, in good yields with high enantiomeric ratios under mild conditions. Experimental and theoretical studies have been conducted to elucidate the reaction mechanism, revealing how the enatiotopic-group-selective transmetalation of gem-diborylalkanes with chiral copper complex occurs to generate chiral α-borylalkyl-copper species for the first time. Additional synthetic applications to the synthesis of various chiral building blocks are also included.
- Kim, Minjae,Park, Bohyun,Shin, Minkyeong,Kim, Suyeon,Kim, Junghoon,Baik, Mu-Hyun,Cho, Seung Hwan
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supporting information
p. 1069 - 1077
(2021/01/25)
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- Synthesis of Six-Membered Spiro Azacyclic Oxindole Derivatives via a One-Pot Process of Umpolung Allylation/Aza-Prins Cyclization
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An unprecedented synthetic approach involving umpolung allylation/aza-Prins cyclization of N-2,2,2-trifluoroethylisatin ketimines is described. The reactions proceed smoothly with allyl bromide in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene, H2O, and trimethylsilyl bromide; this one-pot protocol allows access to six-membered spiro azacyclic oxindole derivatives in good to excellent yields. Notably, while the general aza-Prins cyclization involves amines and aldehydes, the present synthetic strategy represents the first aza-Prins cyclization that utilizes the umpolung property of N-2,2,2-trifluoroethylisatin ketimines.
- Jang, Woo Cheol,Jung, Myeongjin,Ko, Haye Min
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supporting information
p. 1510 - 1515
(2021/03/03)
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- Asymmetric Reductive and Alkynylative Heck Bicyclization of Enynes to Access Conformationally Restricted Aza[3.1.0]bicycles
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Conformationally restricted azabicycles are becoming increasingly important in medicinal research. Asymmetric Heck bicyclization of enynes proceeds to give medicinally useful aza[3.1.0] and aza[4.1.0] bicycles with excellent enantioselectivity. The key organopalladium species after bicyclization can be trapped by silanes and terminal alkynes.
- Chi, Yonggui Robin,Huang, Xiaolei,Nguyen, Minh Hieu,Pu, Maoping,Wu, Yun-Dong,Zhang, Luoqiang,Zhou, Jianrong Steve
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supporting information
p. 10814 - 10818
(2020/06/09)
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- Enantioselective Synthesis of 4-Allyl Tetrahydroquinolines via Copper(I) Hydride-Catalyzed Hydroallylation of 1,2-Dihydroquinolines
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CuCl/(R,R)-Ph-BPE-catalyzed asymmetric hydroallylation of 1,2-dihydroquinolines, prepared from readily available quinolines, was developed. The optically active tetrahydroquinolines (THQs) bearing an allylic functionality at position 4 were obtained in good yields and excellent enantioselectivity. The introduced allylic groups are amenable to diverse transformations, thus offering chances to rapidly expand the THQ libraries.
- Xu-Xu, Qing-Feng,You, Shu-Li,Zhang, Xiao
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supporting information
p. 1530 - 1534
(2020/03/13)
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- Palladium-Catalyzed Regioselective Aerobic Allylic C?H Oxygenation: Direct Synthesis of α,β-Unsaturated Aldehydes and Allylic Alcohols
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A protocol for the synthesis of α,β-unsaturated aldehydes and allylic alcohols from simple allylic hydrocarbons with water via palladium-catalyzed functionalization of allylic C?H bonds was described. Molecular oxygen is utilized as the sole oxidant in this oxygenation of terminal alkenes. This protocol features good functional group compatibility, broad substrate scope, and high atom- and step-economy. Moreover, the synthetic utility of this method can be highlighted by its application to the synthesis of ibuprofen, which is a highly potent analgesic. (Figure presented.).
- Li, Chunsheng,Chen, Huoji,Li, Jianxiao,Li, Meng,Liao, Jianhua,Wu, Wanqing,Jiang, Huanfeng
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supporting information
p. 1600 - 1604
(2018/03/05)
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- Traversing Steric Limitations by Cooperative Lewis Base/Palladium Catalysis: An Enantioselective Synthesis of α-Branched Esters Using 2-Substituted Allyl Electrophiles
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Cooperative catalysis enables the direct enantioselective α-allylation of linear prochiral esters with 2-substituted allyl electrophiles. Critical to the successful development of the method was the recognition that metal-centered reactivity and the sourc
- Schwarz, Kevin J.,Pearson, Colin M.,Cintron-Rosado, Gabriel A.,Liu, Peng,Snaddon, Thomas N.
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supporting information
p. 7800 - 7803
(2018/06/26)
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- Enantioselective bromocyclization of allylic amides catalyzed by BINAP derivatives
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A highly enantioselective bromocyclization of allylic amides with N-bromosuccinimide (NBS) was developed with DTBM-BINAP as a catalyst, affording chiral oxazolines with a tetrasubstituted carbon center in high yield with up to 99% ee. By utilizing the bro
- Kawato, Yuji,Kubota, Akino,Ono, Hiromi,Egami, Hiromichi,Hamashima, Yoshitaka
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supporting information
p. 1244 - 1247
(2015/03/14)
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- N-BuLi/LiCH2CN-mediated one-carbon homologation of aryl epoxides into conjugated allyl alcohols
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A series of styrene oxides in the presence of a 1:1 mixture of n-butyllithium (n-BuLi) and lithioacetonitrile (LiCH2CN) in THF are converted into one-carbon homologated allyl alcohols in an unusual regioselective manner.
- Tomioka, Takashi,Sankranti, Rambabu,Yamada, Tsuyoshi,Clark, Courtney
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supporting information
p. 5099 - 5101
(2013/10/22)
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- Solvent-dependent enantiodivergence in the chlorocyclization of unsaturated carbamates
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A remarkable solvent-controlled enantiodivergence is seen in the hydroquinidine 1,4-phthalazinediyl diether ((DHQD)2PHAL)-catalyzed chlorocyclization of unsaturated carbamates. Eyring plot analyses of this previously unreported reaction are used to probe and compare the R- and S-selective pathways. In the CHCl3/hexanes solvent system, the pro-R process shows a surprising increase in selectivity with increasing temperature. These studies point to a strongly solvent-dependent entropy-enthalpy balance between the pro-R and pro-S pathways. Two solvents, two enantiomers: Enantiodivergent hydroquinidine 1,4-phthalazinediyl diether ((DHQD) 2PHAL)-catalyzed chlorocyclization of unsaturated carbamates, controlled solely by the choice of solvent, yields oxazolidinones in high enantioselectivity (see scheme; DCDMH=1,3-dichloro-5,5-dimethyl hydantoin). The origin of the observed enantiodivergence is traced back to a solvent-selected entropy-enthalpy balance between pro-R and pro-S pathways that dictates the course of the reaction. Copyright
- Garzan, Atefeh,Jaganathan, Arvind,Salehi Marzijarani, Nastaran,Yousefi, Roozbeh,Whitehead, Daniel C.,Jackson, James E.,Borhan, Babak
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supporting information
p. 9015 - 9021
(2013/07/26)
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- Synthesis of quaternary carbon centers via hydroformylation
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The application of hydroformylation to the synthesis of quaternary carbon centers is reported. The synthesis of the highly substituted carbon is achieved by applying a catalytic amount of 1. Ligand 1 serves as a catalytic directing group by covalently and reversibly binding to both the substrate and catalyst. The intramolecular nature of the directing group strategy accelerates the hydroformylation reaction such that the reaction is performed at mild temperatures (35-55 °C) and with excellent regioselectivity (b:l > 94:6).
- Sun,Frimpong,Tan
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supporting information; experimental part
p. 11841 - 11843
(2010/11/04)
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- The Synthesis of (R)-(-) and (S)-(+)-Hydroxysaclofen
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2-(4-Chlorophenyl)-3-hydroxypropene has been separately converted to both enantiomers of its epoxide.The epoxides were converted to (R)-(-) and (S)-(+)-hydroxysaclofen.Only the latter showed activity as a specific GABAB antagonist.
- Prager, Rolf H.,Schafer, Karl,Hamon, David P. G.,Massy-Westropp, Ralph A.
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p. 11465 - 11472
(2007/10/02)
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- 2,4,4-tri- and 2,2,4,4-tetra substituted-1,3-dioxolane antifungal, antiallergy compounds
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Novel 1,3-dioxolane compounds useful as antifungal and antiallergy agents and represented by the formula STR1 wherein Ar is thienyl, pyridyl, biphenyl, phenyl or phenyl substituted by one or more of halo, nitro, cyano, lower alkyl, lower alkoxy or perhalo
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- Effect of the α-Trifluoromethyl Moiety on the Solvolysis of Allylic Sulfonates
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A series of allylic sulfonates bearing aryl substituents on the 2-position and/or trifluoromethyl groups on the 1- and/or 3-positions has been studied under solvolytic conditions in 2,2,2-trifluoroethanol.Nonarylated 1,3-di(trifluoromethyl)-substituted allylic sulfonates did not solvolyze in a conventional manner but instead gave products diagnostic of a complex isomerization-cleavage process.Mono(trifluoromethyl)-substituted allylic sulfonates solvolyzed by normal paths to give kH/kCF3 ratios of 2E6 and 4E4 for the substitution at the 1- and 3-positions, respectively.No evidence for 1,3-? interactions was discerned.
- Gassman, Paul G.,Harrington, Clinton K.
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p. 2258 - 2273
(2007/10/02)
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