- Iridium-Catalyzed γ-Selective Hydroboration of γ-Substituted Allylic Amides
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Reported here for the first time is the Ir-catalyzed γ-selective hydroboration of γ-substituted allylic amides under mild reaction conditions. A variety of functional groups could be compatible with reaction conditions, affording γ-branched amides in good yields with ≤97% γ-selectivity. We have also demonstrated that the obtained borylated products could be used in a series of C-O, C-F, C-Br, and C-C bond-forming reactions.
- Zhao, Hongliang,Gao, Qian,Zhang, Yajuan,Zhang, Panke,Xu, Senmiao
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supporting information
p. 2861 - 2866
(2020/04/02)
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- Iridium-Catalyzed Distal Hydroboration of Aliphatic Internal Alkenes
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The regioselective hydroboration of aliphatic internal alkenes remains a great challenge. Reported herein is an iridium-catalyzed hydroboration of aliphatic internal alkenes, providing distal-borylated products in good to excellent yields with high regioselectivity (up to 99:1). We also demonstrate that the C?B bond of the distal-borylated product can be readily converted into other functional groups. DFT calculations indicate that the reaction proceeds through an unexpected IrIII/IrV cycle.
- Wang, Guangzhu,Liang, Xinyi,Chen, Lili,Gao, Qian,Wang, Jian-Guo,Zhang, Panke,Peng, Qian,Xu, Senmiao
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supporting information
p. 8187 - 8191
(2019/05/27)
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- A practical copper-catalyzed approach to β-lactams: via radical carboamination of alkenyl carbonyl compounds
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Functionalized β-lactams are highly important motifs in synthetic chemistry. We report an efficient and novel approach to the synthesis of β-lactams via a copper(i)-catalyzed cascade process involving C(benzyl)-H radical abstraction, intermolecular alkene addition, and intramolecular amination reaction. Variously substituted alkenes were synthesized from vinylacetic acid, leading to the corresponding β-lactams in moderate to good yields. Preliminary studies indicate that the reaction undergoes a free radical mechanism via a Cu(i)/Cu(ii)/Cu(iii) catalytic cycle.
- Shi, Peng,Wang, Jie,Gan, Zixu,Zhang, Jingyu,Zeng, Runsheng,Zhao, Yingsheng
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supporting information
p. 10523 - 10526
(2019/09/06)
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- Stereoselective Synthesis of Highly Substituted Tetrahydropyrans through an Evans Aldol-Prins Strategy
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A direct and general method for the synthesis of naturally occurring 2,3,4,5,6-pentasubstituted tetrahydropyrans has been developed, employing β,γ-unsaturated N-acyl oxazolidin-2-ones as key starting materials. The combination of the Evans aldol addition and the Prins cyclization allowed the diastereoselective and efficient generation of the desired oxacycles in two fashions: a one-pot Evans aldol-Prins protocol, in which five new σ bonds and five contiguous stereocenters were straightforwardly generated, and a two-step version, which additionally permitted the isolation of β,γ-unsaturated alcohol precursors bearing an N-acyl oxazolidin-2-one in the α position. From these alcohols were also obtained halogenated pentasubstituted tetrahydropyrans as well as 2,3,4,5-tetrasubstituted tetrahydrofurans, shedding light on the mechanism of the process. Computational studies were consistent with the experimental findings, and this innovative Evans aldol-Prins strategy was performed for the preparation of a battery of more than 30 densely substituted tetrahydropyrans, unprecedentedly fused to a 1,3-oxazinane-2,4-dione ring, both in a racemic fashion and in an enantiomeric fashion. These novel molecules were successfully submitted to several transformations to permit simple access to a variety of differently functionalized tetrahydropyrans. Most of these unique molecules were evaluated for their antimicrobial activity against Gram-positive and Gram-negative bacteria and the yeast Candida albicans, and some structure-activity relationships were established.
- álvarez-Méndez, Sergio J.,Fari?a-Ramos, Marta,Villalba, María Luisa,Perretti, Marcelle D.,García, Celina,Moujir, Laila M.,Ramírez, Miguel A.,Martín, Víctor S.
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p. 9039 - 9066
(2018/08/06)
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- Synthetic method for drug intermediate 3-alkenylhexanoic acid
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The invention discloses a synthetic method for the drug intermediate 3-alkenylhexanoic acid. The synthetic method comprises the following steps: adding 2-bromo-3-hexen-1-one and 1.6 L of a potassium nitrate solution into a reaction vessel, controlling a stirring speed to be 110-130 rpm, maintaining a temperature at 30-36 DEG C, carrying out a reaction for 50-70 min, adding an isopropyl butyrate solution, raising a solution temperature to 40-45 DEG C and continuing the reaction for 1-2 h; and then adding molybdenum dichloride powder, controlling the stirring speed to be 220-250 rpm, carrying out a reaction for 60-90 min, then carrying out washing with a diethylene glycol monoethyl ether solution a plurality of times, then carrying out washing with a potassium bromide solution a plurality oftimes, adding a trichloroacetic acid solution to adjust the pH value to 4-5, carrying out extraction with a sulfolane solution a plurality of times, combining extracts, then carrying out washing witha bromoethane solution and a phenetole solution successively, carrying out recrystallization in a solution of N,N-dibutylaniline, and then carrying out dehydrating with a dehydrating agent to obtainthe finished 3-alkenylhexanoic acid.
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Paragraph 0018-0019
(2018/07/30)
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- Catalytic Regio- and Enantioselective Oxytrifluoromethylthiolation of Aliphatic Internal Alkenes by Neighboring Group Assistance
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Chiral selenide-catalyzed oxytrifluoromethylthiolation of aliphatic internal alkenes by a formally intermolecular strategy is disclosed, affording CF3S 1,3-amino alcohol and 1,3-diol derivatives with high regio-, enantio-, and diastereoselectivities. The reactions are promoted by a neighboring imide or ester group on substrates via a six-membered ring transition state. This assistance strategy is also successfully applied to the regio- and diastereoselective oxyhalofunctionalization of internal alkenes and the conversion of alkynes.
- Xu, Jia,Zhang, Yuanyuan,Qin, Tian,Zhao, Xiaodan
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supporting information
p. 6384 - 6388
(2018/10/09)
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- Catalytic Enantioselective Synthesis of 2,5-Dihydrooxepines
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A Michael addition initiated cyclopropanation/retro-Claisen rearrangement tandem reaction was developed for the enantioselective synthesis of highly functionalized 2,5-dihydrooxepines. In the presence of a chiral oxazaborolidinium ion (COBI) catalyst, the reaction proceeds to give good yields and high enantioselectivity.
- Shim, Su Yong,Cho, Soo Min,Venkateswarlu, Anipireddy,Ryu, Do Hyun
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supporting information
p. 8663 - 8666
(2017/07/17)
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- Selective isomerization-hydroformylation sequence: A strategy to valuable α-methyl-branched aldehydes from terminal olefins
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For the first time, an original selective isomerization-hydroformylation sequence to convert terminal olefins bearing an anionic moiety to α-methyl-branched aldehydes with unprecedented selectivities is reported. This opens up new synthetic avenues to these valuable building blocks from inexpensive and bioavailable substrates. The catalytic system involves a suitable selective monoisomerization catalyst and a selective supramolecular catalyst that preorganizes a substrate molecule prior to the hydroformylation reaction via hydrogen bonding. In principle, the strategy can be extended to other classes of substrates, providing suitable catalysts for the hydroformylation of internal alkenes.
- Dydio, Pawel,Ploeger, Marten,Reek, Joost N. H.
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p. 2939 - 2942
(2014/01/06)
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- REDUCTION OF 2,4-ALKEDIENOIC ACIDS WITH SODIUM DITHIONITE
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The reduction of sodium salts of 2,4-alkadienoic acids bearing alkyl substituents in the different positions of the diene system, in aqueous solution with sodium dithionite, affords E:Z isomeric mixtures of 3-alkenoic acids after acidification.These results are compared with those reported with those reported for the related reaction under phase transfer catalysis of the corresponding alkyl alkadienoates.Formation of sulfinic adducts as intermediates in the reduction of sorbic acid points to a two stage mechanism for the overall reduction process.
- Camps, Francisco,Coll, Josep,Guitart, Josefa
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p. 185 - 194
(2007/10/02)
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- REDUCTION OF CONJUGATED DIENOIC CARBOXYLIC ACIDS AND ESTERS WITH SODIUM DITHIONITE
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Reduction of 2,4-alkadienoic acids and esters with sodium dithionite was carried out in aqueous solution or under PTC conditions to give, almost excusively, Z:E isomeric mixtures of the corresponding 3-alkenoic acids and esters, respectively, in good yields.
- Camps, Francisco,Coll, Jose,Guerrero, Angel,Guitart, Josefa,Riba, Magi
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p. 715 - 718
(2007/10/02)
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- 2,6-Disubstituted penem compounds
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This invention relates to 2-substituted and 2,6-disubstituted penem compounds of the formula STR1 wherein Y is hydrogen, halo or certain organic radicals and X represents certain hetero-interrupted substituted alkyl radicals. Also included in the invention are pharmaceutically acceptable salts of the above compounds and derivatives of the above compounds in which the carboxyl group at the 3-position is protected as by an easily removable ester protecting group. The compounds of the present invention are potent antibacterial agents or are of use as intermediates in the preparation of such agents.
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- Antibacterial agents, and 4-thio azetidinone intermediates
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This invention relates to 2-substituted and 2,6-disubstituted penem compounds of the formula STR1 wherein Y is hydrogen, halo or certain organic substituents and X represents certain organic substituents. Also included in the invention are pharmaceutically acceptable salts of the above compounds and derivatives of the above compounds in which the carboxyl group at the 3-position is protected as by an easily removable ester protecting group. The compounds of the present invention are potent antibacterial agents or are of use as intermediates in the preparation of such agents.
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- A CONVENIENT METHOD FOR THE SYNTHESIS OF (E)-3-ALKENOIC ACIDS BY A REGIO- AND STEREOSELECTIVE REACTION OF β-VINYL-β-PROPIOLACTONE WITH ORGANOCOPPER REAGENTS
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β-Vinyl-β-propiolactone reacts regio- and stereoselectively with Grignard reagents in the presence of copper(I) catalyst or with diorganocuprates to afford (E)-3-alkenoic acids in high yields.
- Sato, Toshio,Takeuchi, Masashi,Itoh, Toshiyuki,Kawashima, Masatoshi,Fujisawa, Tamotsu
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p. 1817 - 1820
(2007/10/02)
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