- Synthesis of Cyclic Anhydrides via Ligand-Enabled C–H Carbonylation of Simple Aliphatic Acids
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The development of C(sp3)–H functionalizations of free carboxylic acids has provided a wide range of versatile C?C and C?Y (Y=heteroatom) bond-forming reactions. Additionally, C–H functionalizations have lent themselves to the one-step preparation of a number of valuable synthetic motifs that are often difficult to prepare through conventional methods. Herein, we report a β- or γ-C(sp3)–H carbonylation of free carboxylic acids using Mo(CO)6 as a convenient solid CO source and enabled by a bidentate ligand, leading to convenient syntheses of cyclic anhydrides. Among these, the succinic anhydride products are versatile stepping stones for the mono-selective introduction of various functional groups at the β position of the parent acids by decarboxylative functionalizations, thus providing a divergent strategy to synthesize a myriad of carboxylic acids inaccessible by previous β-C–H activation reactions. The enantioselective carbonylation of free cyclopropanecarboxylic acids has also been achieved using a chiral bidentate thioether ligand.
- Herron, Alastair N.,Yu, Jin-Quan,Zhuang, Zhe
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supporting information
p. 16382 - 16387
(2021/06/23)
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- kalong acid, carrondo anhydried novel method for the synthesis of
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The invention relates to new synthesis methods of caronaldehydic acid hemiacetal, caronic acid and caronic anhydride. Hydroxyl-protected isopentenyl alcohol is adopted as a starting material, then a three-membered ring key intermediate is generated throug
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Paragraph 0193-0197
(2016/10/17)
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- Highly enantioselective hydrogenative desymmetrization of bicyclic imides leading to multiply functionalized chiral cyclic compounds
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Highly enantioselective hydrogenative desymmetrization of bicyclic imides has been developed with chiral CpRu(PN) catalysts. The present hydrogenation directly provides stereochemically well-defined cyclic compounds with excellent enantiomeric exessses, which might otherwise require a detour to reach.
- Ito, Masato,Kobayashi, Chika,Himizu, Akio,Ikariya, Takao
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supporting information; experimental part
p. 11414 - 11415
(2010/10/03)
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- DEHYDROHALOGENATION PROCESS FOR THE PREPARATION OF INTERMEDIATES USEFUL IN PROVIDING 6,6-DIMETHYL-3-AZABICYCLO-[3.1.0]-HEXANE COMPOUNDS
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The present invention provides for a process for preparing the pyrrole compounds of Formula Va and Vb.
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Page/Page column 27
(2009/07/17)
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- PROCESS FOR THE PREPARATION OF 6, 6-DIMETHYL-3-AZABICYCLO-[3.1.0]-HEXANE COMPOUNDS AND ENANTIOMERIC SALTS THEREOF
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The present invention provides for a process for preparing racemic methyl 6,6-dimethyl-3-azabicyclo[3,1,0]hexane-2-carboxylate, its corresponding salt: (2S, 3R, 4S)-methyl 6,6-dimethyl-3-azabicyclo[3,1,0]hexane-2-carboxylate di-p-toluoyl-D-tartaric acid ("D-DTTA") salt or a (2R, 3S, 4R)-methyl 6,6-dimethyl-3-azabicyclo[3,1,0]hexane-2-carboxylate di-p-toluoyl-L-tartaric acid salt ("L-DTTA") in a high enantiomeric excess. This invention also provides for a process for preparing a (2S, 3R, 4S)-methyl 6,6-dimethyl-3-azabicyclo[3,1,0]hexane-2-carboxylate dibenzoyl-D-tartaric acid ("D-DBTA") salt or a (2R, 3S, 4R)-methyl 6,6-dimethyl-3-azabicyclo[3,1,0]hexane-2-carboxylate L-tartaric acid ("L-DBTA") salt in a high enantiomeric excess. Further, this invention provides a process for preparing intermediates II, IIB, III, IV, IV salt, V, VI, and VII.
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Page/Page column 27-28
(2008/06/13)
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- PROCESS AND INTERMEDIATES FOR THE PREPARATION OF (1R,2S,5S)-6,6-DIMETHYL-3-AZABICYCLO[3,1,0]HEXANE-2-CARBOXYLATES OR SALTS THEREOF
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In one embodiment, the present application relates to a process of making a compound of Formula (I); and to certain intermediate compounds that are made within the process of making the compound Formula (I).
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Page/Page column 23
(2008/06/13)
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- Ozonolysis of (1R,cis)-4,7,7-trimethyl-3-oxabicyclo[4.1.0]hept-4-en-2-one
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The structure of peroxides forming in ozonolysis of enololactone and their further transformations are determined by the structure of the initial substrate and by effect of solvent used for ozonolysis.
- Kukovinets,Kasradze,Galin,Spirikhin,Zainullin,Kislitsyn,Abdullin,Kunakova,Tolstikov
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p. 511 - 518
(2007/10/03)
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- Synthesis, stereochemistry, and chiroptical spectra of cyclopropyl lactones and thionolactones
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Several optically active substituted 3-oxabicyclo[3.1.0]hexan-2-ones and their thiocarbonyl analogues were synthesized, and their circular dichroism spectra are reported. It was found that the n-π* Cotton effect sign is determined by the helicity of an inherently chiral chromophore formed by the lactone or thiolactone group and the cyclopropyl moiety. The π-π* Cotton effect of thiocarbonyl compounds shows opposite sign to that observed for the lowest energy transition. The crystal structures of two compounds were solved to establish their molecular geometries. Copyright (C) Elsevier Science Ltd.
- Milewska, Maria J.,Gdaniec, Maria,Polonski, Tadeusz
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p. 3169 - 3180
(2007/10/03)
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- Cyclopropanediamines, 3. - Pure Diastereomers of 1,2-Cyclopropanedicarboxylic Acids and Derivatives
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Efficient preparations of pure diastereomers of dimethyl 1,2-cyclopropanedicarboxylates 2, dicarboxylic acids 3, dicarbonyl dichlorides 4, and dihydrazides 5 are reported.Mixtures of diastereomers of dimethyl dicarboxylates 2a, b, d, e are obtained from α,β-unsaturated methyl carboxylates 7 and methyl α-chlorocarboxylates 8 as well as from 7c, d and the sulfur ylide 10 (2c, d).The diastereomers are separated by fractionating distillations (2a, b, c, e) or crystallization (2d) on a 100-g to 1-kg scale (d.e. >99percent).Only low yields of 2c are obtained in the reaction of methyl crotonate (7c) with methyl α-chloroacetate (8a), since 7c predominantly dimerizes to afford 12.The diesters 2 are converted into the pure diastereomeric diacids 3, dicarbonyl dichlorides 4, and dihydrazides 5. 3,3-Dimethyl-cis-1,2-cyclopropanedicarboxylic acid (cis-3f) is obtained by trans-->cis isomerization of trans-3f with the help of acetic anhydride and sodium acetate as catalyst.The configurations of 2-6 and 12 are confirmed by 1H NMR spectroscopy.Derivatives of cis-1,2-dimethyl-1,2-cyclopropanedicarboxylic acid tend to form bicyclic products.Thus, the reaction of cis-3e with phosphorus pentachloride yields mainly the cyclic anhydride 6e and only small amounts of the dicarbonyl dichloride cis-4e.Furthermore, the dihydrazide cis-5e slowly cyclizes in the solid state to give the N-aminoimide 13 and hydrazine, a reaction which is fast in solution.Pure 13 is obtained by thermolysis of cis-5e at 60-65 deg C under high vacuum.
- Saal, Wolfgang von der,Reinhardt, Robert,Seidenspinner, Hubert-Matthias,Stawitz, Josef,Quast, Helmut
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p. 703 - 712
(2007/10/02)
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