- A de Novo Synthetic Route to 1,2,3,4-Tetrahydroisoquinoline Derivatives
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A novel synthetic approach was developed for the construction of the 1,2,3,4-tetrahydroisoquinoline framework possessing varied functions. The synthetic strategy was based on oxidative ring opening of some indene derivatives through their C=C bond, followed by double reductive amination of the dicarbonyl intermediates with various primary alkyl- or fluoroalkylamines.
- ábrahámi, Renáta A.,Fustero, Santos,Fül?p, Ferenc,Kiss, Loránd
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supporting information
p. 2066 - 2070
(2018/03/29)
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- Bioinspired Total Synthesis of (±)-Chaetophenol C Enabled by a Pd-Catalyzed Cascade Cyclization
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A novel Pd(II)-catalyzed cascade reaction has been developed that consists of a highly regio- and stereoselective oxa [4 + 2] cycloaddition reaction of o-alkynylbenzaldehydes and an intramolecular carboxylic group quenching of the in situ generated oxonium ion. This new reaction provides a one-step construction of the tetracyclic core structure of chaetophenol C from two simple starting materials. The developed chemistry was successfully applied to the first total synthesis of chaetophenol C and dozens of its analogues.
- Li, Yun,Zhang, Qingyu,Wang, Hongyu,Cheng, Bin,Zhai, Hongbin
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p. 4387 - 4390
(2017/08/23)
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- Activated iodosylbenzene monomer as an ozone equivalent: Oxidative cleavage of carbon-carbon double bonds in the presence of water
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Reported here for the first time are the developments of an efficient method for oxidative cleavage of carbon-carbon double bonds yielding carbonyl compounds by using aryl-λ3-iodanes, which involve a combination of iodosylbenzene and HBF4 in the presence of water. The method serves as a safety alternative to ozonolysis. The oxidative cleavage of olefins probably involves the hitherto unknown direct vicinal dihydroxylations of double bonds with aryl-λ3-iodanes and the subsequent oxidative glycol fissions. Cyclic (cyclopentenes, cyclohexenes, etc.) and acyclic olefins are cleaved smoothly under our conditions. In the reaction of electron-deficient styrenes such as m-nitrostyrene, intermediate formation of the corresponding epoxide was detected. A variety of aryloxiranes also undergo an oxidative cleavage of the epoxide rings under our conditions, and aromatic aldehydes were obtained in good yields. Copyright
- Miyamoto, Kazunori,Tada, Norihiro,Ochiai, Masahito
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p. 2772 - 2773
(2007/10/03)
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- Enantioselective formation of quaternary stereocenters using the catalytic intramolecular Stetter reaction
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Asymmetric formation of quaternary stereocenters has been accomplished using the catalytic intramolecular Stetter reaction. A?variety of tethered aldehydes and Michael acceptors are cyclized in excellent yields and enantioselectivities.
- Moore, Jennifer L.,Kerr, Mark S.,Rovis, Tomislav
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p. 11477 - 11482
(2007/10/03)
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- Thiazol-2-ylidene catalysis in intramolecular crossed aldehyde-ketone benzoin reactions
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Intramolecular crossed aldehyde-ketone benzoin-type reactions catalyzed by nucleophilic carbenes, easily generated from commercially available thiazolium salts as precatalysts, are described. Five- and six-membered cyclic acyloins are obtained in moderate to good yields. Depending on the structure of the aldehyde-ketone substrate, an interchange of the alcohol and ketone function of the resulting acyloin is possible. Simple aldehyde-ketones are not good substrates due to the competing intermolecular reaction. Starting from biphenyl-2,2′-dicarbaldehyde, the intermediate acyloin is converted to 9,10-phenanthrenequinone by mild air oxidation.
- Enders, Dieter,Niemeier, Oliver
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p. 2111 - 2114
(2007/10/03)
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- Mechanistic imperatives for catalysis of aldol addition reactions: Partitioning of the enolate intermediate between reaction with bronsted acids and the carbonyl group
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The lyoxide ion catalyzed intramolecular aldol addition reaction of 2- (2-oxopropyl)benzaldehyde (1) to give the aldol adduct 3 proceeds via essentially irreversible formation of the acetone-like enolate intermediate 2, because reprotonation of 2 by a solvent of H2O or D2O (k(HOH) or k(DOD)) is much slower than intramolecular addition of the enolate to the carbonyl group (k(c)). The aldol addition reaction of 1 catalyzed by high concentrations of 3-substituted quinuclidine buffers proceeds via reversible deprotonation of 1 to give the enolate 2, and rate-determining addition of the enolate to the carbonyl group. A rate constant ratio of k(c)/k(HOH) = 35 was determined for partitioning of the enolate 2 between intramolecular addition to the carbonyl group and protonation by solvent water. The corresponding ratios k(BH)/k(c) (M-1) for the protonation of 2 by Bronsted buffer acids and intramolecular aldol addition increase from 7 to 450 as the acidity of the buffer acid is increased from pK(BH) = 11.5 to 7.5. The data show that the electrophilic reactivity of the benzaldehyde carbonyl group toward intramolecular addition of the enolate 2 is the same as that of a hypothetical tertiary ammonium cation of pK(BH) = 13.3. The Marcus intrinsic barrier for addition of the enolate 2 to the carbonyl group is unexpectedly small, which suggests that the transition state for this reaction is stabilized by interactions between the soft-soft acid-base pair. The relevance of this work to chemical and enzymatic catalysis of aldol condensation reactions is discussed.
- Richard, John P.,Nagorski
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p. 4763 - 4770
(2007/10/03)
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- THERMOLYTIC RING OPENING OF ACYLOXYBENZOCYCLOBUTENES: AN EFFICIENT ROUTE TO 3-SUBSTITUTED ISOQUINOLINES
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Upon flash vacuum pyrolysis acyloxybenzocyclobutenes 4 rearrange through an intramolecular 1,5-acyl shift to 2-formylbenzyl ketones 6 which can be converted to 3-substituted isoquinolines 7.
- Schiess, Peter,Huys-Francotte, Martine,Vogel, Caspar
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p. 3959 - 3962
(2007/10/02)
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