- Synthesis and olfactory evaluation of optically active β-alkyl substituted γ-lactones and whiskey lactone analogues
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Optically active β-alkyl substituted γ-lactones and whiskey lactone analogues were synthesized, and the odor properties were evaluated. During the preparation of the chiral intermediates, we found good reaction conditions for the highly enantioselective esterification of 3-arylmethyl-2-methyl-1-propanols to kinetically resolve them. The results of the olfactory evaluations of the synthesized lactones revealed that the alkyl groups on the γ-lactone rings played an important role for the odor profiles.
- Kato, Daiki,Kawasaki, Masashi,Morita, Yuko,Okada, Takuya,Tanaka, Yasuo,Toyooka, Naoki
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supporting information
(2020/02/22)
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- Carbonylative Transformation of Allylarenes with CO Surrogates: Tunable Synthesis of 4-Arylbutanoic Acids, 2-Arylbutanoic Acids, and 4-Arylbutanals
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In this Communication, procedures for the selective synthesis of 4-arylbutanoic acids, 2-arylbutanoic acids, and 4-arylbutanals from the same allylbenzenes have been developed. With formic acid or TFBen as the CO surrogate, reactions proceed selectively and effectively under carbon monoxide gas-free conditions.
- Wu, Fu-Peng,Li, Da,Peng, Jin-Bao,Wu, Xiao-Feng
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supporting information
p. 5699 - 5703
(2019/08/01)
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- Styrene-acrylic acid synthetic method of the compound
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The invention discloses a method for directly achieving direct arylation reaction of benzene and carbonyl beta-bite sp3C-H bonds employing palladium acetate as a catalyst under the action of bidentate guide base, so as to synthesize a phenylpropionic acid compound. The method comprises the following steps: sequentially adding a 2-propionamido-pyridine-1-oxide, palladium acetate, gibbsite dipotassium phosphate, an aryl iodide compound and dimethylsulfoxide to a shrek tube in an air atmosphere, and reacting for 20-30 hours; after the reaction is ended, cooling to a room temperature, extracting, drying, concentrating and carrying out chromatographic separation to obtain an arylated product; dissolving the obtained arylated product into an ethanol solution of NaOH and reacting for 20-30 hours; and after reaction is ended, neutralizing, extracting, drying, concentrating and carrying out column chromatography to obtain the phenylpropionic acid compound. The method is mild in reaction condition, and good in functional group tolerance; an external additive is not needed; and the carbonyl beta-bite sp3C-H bonds in the 2-propionyl aminopyridine-1-oxide can be directly arylated.
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Paragraph 0030; 0046; 0051; 0052
(2017/05/02)
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- Application of acyclic chiral auxiliaries on alkylation reactions
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The application in alkylation reactions of an acyclic chiral auxiliary is described. The synthesis is straightforward from a chiral primary amine and a double acylation. A characteristic of this auxiliary is its modular design formed by an achiral part (acyl) and a chiral component (primary amine) so it can be tuned for different reactions without difficulty. The alkylation proceeds with excellent diastereoselectivity because the conformational flexibility of the enolate is restricted by the formation of a chelate and the allylic 1,3-strain.
- Gardu?o-Castro, Monserrat H.,Hernández-Rodríguez, Marcos
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supporting information
p. 193 - 196
(2014/01/06)
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- Influence of the position of the substituent on the efficiency of lipase-mediated resolutions of 3-aryl alkanoic acids
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Hydrolase-catalysed kinetic resolutions to provide enantioenriched α-substituted 3-aryl alkanoic acids are described. (S)-2-Methyl-3- phenylpropanoic acid (S)-1a was prepared in 96% ee by Pseudomonas fluorescens catalysed ester hydrolysis, while, Candida antarctica lipase B (immob) resolved the α-ethyl substituted 3-arylalkanoic acid (R)-1b in 82% ee. The influence of the position of the substituent relative to the ester site on the efficiency and enantioselectivity of the biotransformation is also explored; the same lipases were found to resolve both the α- and β-substituted alkanoic acids. Furthermore, the steric effect of substituents at the C2 stereogenic centre relative to that for their C3 substituted counterparts on the efficiency and stereoselectivity is discussed.
- Deasy, Rebecca E.,Moody, Thomas S.,Maguire, Anita R.
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p. 1480 - 1487
(2013/12/04)
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- A method to prepare optically active acyclic α-benzyl ketones by thermodynamically controlled deracemization
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Thermodynamically controlled deracemization of some acyclic ketones bearing a chiral center at the position α to the carbonyl group was satisfactorily achieved. Acyclic ketones with high optical purities could be isolated after treatment of the racemic ketones with base in aqueous MeOH in the presence of (-)-(2R,3R)-trans-2,3-bis(hydroxydiphenylmethyl)-1,4-dioxaspiro[5. 4]decane (1a). The efficiency of the deracemization was appreciably influenced by the ratio of H2O/MeOH used as solvent. Racemic ketones bearing a chiral center at the position α to the carbonyl group were converted into optically active ketones in the presence of TADDOL-type host molecule 1a in H2O/MeOH in suspension in basic media. Copyright
- Kaku, Hiroto,Imai, Takahiro,Kondo, Risa,Mamba, Shiho,Watanabe, Yu,Inai, Makoto,Nishii, Takeshi,Horikawa, Mitsuyo,Tsunoda, Tetsuto
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supporting information
p. 8208 - 8213
(2014/01/06)
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- Structural requirements for substrate in highly enantioselective hydrogenation over the cinchonidine-modified Pd/C
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Relationship between substrate structure and enantioselectivity is studied for the asymmetric hydrogenation of 42 different (E)-α, β-disubstituted acrylic acids (propenoic acids) over cinchonidine-modified Pd/C. The β-phenyl group is indispensable for high enantioselectivity of α-phenylcinnamic acid (2,3-diphenylpropenoic acid, 81% ee), and substitution on this group affects markedly the selectivity. The high ee up to 92% was achieved by the β - p-alkoxyphenyl substitution, and the selectivity is ascribed mainly to stronger interaction of the substrate with the chiral modifier on the catalyst surface. In contrast, substitution on the α-phenyl group does not affect notably the enantioselectivity (80-82% ee) or even the α-phenyl group itself is not indispensable but replaceable with a properly bulky group for the high enantioselectivity.
- Sugimura, Takashi,Uchida, Takayuki,Watanabe, Junya,Kubota, Takeshi,Okamoto, Yasuaki,Misaki, Tomonori,Okuyama, Tadashi
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experimental part
p. 57 - 64
(2009/06/17)
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- Remarkable electronic and steric effects in the nitrile biotransformations for the preparation of enantiopure functionalized carboxylic acids and amides: Implication for an unsaturated carbon-carbon bond binding domain of the amidase
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(Chemical Equation Presented) Biotransformations of various functionalized racemic nitriles catalyzed by Rhodococcus erythropolis AJ270, a nitrile hydratase/amidase-containing microbial whole-cell catalyst, were studied. While the nitrile hydratase exhibi
- Gao, Ming,Wang, De-Xian,Zheng, Qi-Yu,Huang, Zhi-Tang,Wang, Mei-Xiang
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p. 6060 - 6066
(2008/02/10)
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- Asymmetric synthesis of novel α-amino acids with β-branched side chains
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An asymmetric synthesis of α-amino acids with novel β-branched side chains has been implemented. The syntheses feature a p-toluenesulfinylimine induced chiral Strecker approach and were found to be applicable to the introduction of both aliphatic and aromatic β-branched sidechains for preparation of previously unknown α-amino acids.
- Zhang, Minsheng,Porte, Alex,Diamantidis, George,Sogi, Kimberly,Kubrak, Dennis,Resnick, Lynn,Mayer, Scott C.,Wang, Zheng,Kreft, Anthony F.,Harrison, Boyd L.
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p. 2401 - 2403
(2008/02/03)
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- Design and synthesis of a new polymer-supported Evans-type oxazolidinone: An efficient chiral auxiliary in the solid-ph ase asymmetric alkylation reactions
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Wang resin-supported Evans' chiral auxiliary (23) was designed based on a novel polymer-anchoring strategy, which utilizes the 5-position of the oxazolidinone ring, and its new synthetic route applicable to multi-gram preparation in just a day was developed. Solid-phase Evans' asymmetric alkylation on 23-derived N-acylimide resin and following lithium hydroperoxide-mediated chemoselective hydrolysis afforded the corresponding α-branched carboxylic acids in desired high stereoselectivities (up to 97% ee) and moderate to good overall yield (up to 70%, for 3 steps), which were comparable to those of the conventional solution-phase methods. Furthermore, recovery and recycling of the polymer-supported chiral auxiliary were successfully achieved without decreasing the stereoselectivity of the product. Therefore, this is the first successful example that the solid-phase Evans' asymmetric enolate-alkylation was efficiently performed on the solid-support, and it is concluded that the connection to the solid-support via the 5-position of the oxazolidinone ring is an ideal strategy in the solid-phase Evans' chiral auxiliary.
- Kotake, Tomoya,Hayashi, Yoshio,Rajesh,Mukai, Yoshie,Takiguchi, Yuka,Kimura, Tooru,Kiso, Yoshiaki
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p. 3819 - 3833
(2007/10/03)
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- Pyran-2-ones and 5,6-dihydropyran-2-ones useful for treating hyperplasia and other diseases
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Certain 2H-pyran-2-ones are useful for treating benign prostatic hypertrophy or hyperplasia, prostatic cancer, alopecia, hirsutism, acne vulgaris and seborrhea.
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- Concerted and stepwise Grignard additions, probed with a chiral Grignard reagent
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The Grignard reagent 6, in which the magnesium-bearing carbon atom is the sole stereogenic centre has been added to CO2, PhNCO, PhNCS and certain aldehydes with full retention of configuration. Reaction with benzophenone, electron-deficient aldehydes and several allyl halides proceeded with partial or complete racemization. The findings are discussed with respect to a dichotomy between concerted polar and stepwise SET reaction pathways.
- Hoffmann,Hoelzer
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p. 491 - 492
(2007/10/03)
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- Chiral N-Acyl-tert-butanesulfinamides: The "Safety-Catch" Principle Applied to Diastereoselective Enolate Alkylations
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Diastereoselective enolate alkylation reactions of N-acylsulfmamides and conversion of the alkylation products to a variety of enantiopure products are reported. Several sulfinamides were prepared in solution followed by acylation to provide N-acylsulfmamides. The N-acylsulfinamides were then evaluated in diastereoselective enolate alkylation reactions. Of the sulfinamides evaluated, tert-butanesulfinamide provided the highest diastereoselectivity. To establish the potential utility of sulfinamides as versatile auxiliaries, methods were developed for (1) the racemization-free acylation of tert-butanesulfinamide to prepare optically pure N-acyl-tert-butanesulfinamides, (2) the diastereoselective C-alkylation of N-acyl-tert-butanesulfmamides, (3) the conversion of the N-acyl-tert-butanesulfmamides to the active ester equivalent by N-alkylation and S-oxidation, and (4) the cleavage of the N-alkyl-N-acyl-tert-butanesulfonamides to give chiral alcohol, ester, amide, and carboxylic acid target compounds. These studies provide the groundwork for the development of sulfinamides as dual chiral auxiliaries and linkers for the multistep solid-phase synthesis of enantioenriched compounds.
- Backes, Bradley J.,Dragoli, Dean R.,Ellman, Jonathan A.
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p. 5472 - 5478
(2007/10/03)
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- XANTHINE DERIVATIVES AS ADENOSINE A1 RECEPTOR ANTAGONISTS
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A method of attenuating a cognitive deficit in a patient in need thereof comprising administering to the patient a xanthine derivative.
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- A New Method for the Synthesis of α-Bromoacyl Silanes via Ring-opening of 2-Phenylsulphonyl-2-trimethylsilyloxiranes
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2-Phenylsulphonyl-2-trimethylsilyloxiranes 2 are efficiently prepared by treatment of 2-phenyl-sulphonyloxiranes 3 with butyllithium in the presence of chlorotrimethylsilane at low temperatures.Reaction of 3-alkyl-2-phenylsulphonyl-2-trimethylsilyloxiranes 2, in which the alkyl group is primary, with magnesium bromide at room temperature gives 2-bromoacyl silanes 1 in good yield.Reaction at higher temperatures leads to competing formation of bromovinyl sulphones 7.Reaction of 3,3-dialkyloxiranes with magnesium bromide occurs much more readily, leading to 2-bromoacyl silanes 1 in moderate yields.Other products derived from a common carbocationic intermediate are also isolated.
- Hewkin, Cheryl T.,Jackson, Richard F. W.
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p. 3103 - 3112
(2007/10/02)
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- CHEMOENZYMATIC SYNTHESIS OF THE ENANTIOMERS OF IOPANOIC ACID
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The two enantiomers of Iopanoic acid 1 were prepared in enantiomeric excess higher than 90percent by enzyme-catalyzed hydrolysis of precursors (+/-)-2a and (+/-)-3a, followed by standard chemical transformations.Among the tested enzymes, chymotrypsin and Lipase PS proved to be the most selective catalysts.The stereochemical outcome of the lipase-catalyzed hydrolyses of esters (+/-)-2a-d is strictly dependent upon both the size of the alkyl group attached to the chiral center and the substituent in the aromatic ring.The enantioselectivity of the reactions was evaluated by chiral HPLC and the configurations of the new products were assigned by chemical correlations.
- Colombo, M.,Amici, M. De,Micheli, C. De,Pitre, D.,Carrea, G.,Riva, S.
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p. 1021 - 1030
(2007/10/02)
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- Selective adenosine receptor agents
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Xanthine derivative which act selectively at adenosine receptors and which act in general as adenosine antagonists are disclosed. From in vitro studies it is known that specific physiological effects can be distinguished as a result of this selectively and that adenosine receptor activity in vitro correlates with adenosine receptor activity in vivo.Pharmaceutical preparations of the subject compounds can be prepared on the basis of the selective binding activity of the compounds disclosed herein which will enhance certain physiological effects while minimizing others, such as decreasing blood pressure without decreasing heart rate.
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- Conformations and Rotational Barriers of 1,3-Diphenylallyllithium Compounds
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The phenyl substituents of the 1,3-diphenylallyl anions 10 (gegenion lithium, solvent tetrahydrofuran) can exist in the exo,exo-, endo,exo- and/or endo,endo-conformations.We have investigated the influence of substituents R at C2 on the equilibria of these solvent separated ion pairs.While 10a (R = H) is the only one to exist predominantly in the exo,exo-conformation, and in 10b and c (R = CH3 and CN, respectively) the endo,exo-conformers predominate, in 10d, e and f (R = C2H5, C6H5 and iPr, respectively) there is increasing preference for the endo,endo-conformation, which in 10g (R = tBu) is the dominant (>/= 95percent) conformation.A vast congestion in the endo,endo-conformation is avoided by a rotation of the phenyl rings out of the plane of the allyl carbon atoms, and an expansion of the sp2 angles in the allyl moiety.The rotational barriers around the allyl anion bonds decrease from 19.1 kcal*mol-1 (10a) to 12.5 kcal*mol-1 (10f).Since this trend parallels to the above mentioned shift of the equilibria, it is due to ground state effects.The rotational barriers are only slightly (10a,b) if at all influenced by gegenion effects, which is in sharp contrast to the parent allyl "anion".Therefore, the rotational barriers of the allyl anions 10 are qualified for a comparison with the corresponding radicals and cations.Furthermore, with ΔG(excit)273 deg C = 19.1 kcal*mol-1 as a lower limit value for the rotational barrier of the parent allyl anion, one can estimate that the true value of this species must be close to barriers calculated with STO-3G and 4-3l-G programs (ca. 26 kcal*mol-1).
- Boche, Gernot,Buckl, Klaus,Martens, Diether,Schneider, Dieter R.
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p. 1135 - 1171
(2007/10/02)
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- Indaneacetic acid derivatives
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This invention provides new compounds of formula I, STR1 wherein R1 is lower alkyl, R2 is hydrogen or lower alkyl, R3 is hydrogen or lower alkyl, R4 is hydrogen or lower alkyl, R5 is hydrogen, chlorine or lower alkyl, and each of R6 and R7 is hydrogen, or, when R5 is hydrogen, R6 may also be chlorine or lower alkyl, and R7 chlorine or lower alkyl, Useful as anti-phlogistic and anti-arthritic agents.
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- Iodine containing organic carbonates for use as radiographic agents
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Iodo-aryl carbonates, such as for example, p-iodo-benzyl carbonates, p-iodo-sec-phenethyl carbonates, p-iodo-phenethyl carbonates, p-iodo-phenyl carbonates, 3-(p-iodophenyl)propyl carbonates, 3-(p-iodophenyl)butyl carbonates, 2-(p-iodobenzyl)butyl carbonates and 2-(p-iodobenzyl)-n-hexyl carbonates, for use as radiographic media in connection with such techniques as x-ray applications including myelography, salpingography, lymphography and bronchography. An effective quantity of iodinated organic carbonate provides x-ray contrast, and the compounds of the invention may be characterized generally as carbonates having the general formula STR1 wherein R represents an alkyl group having from 4 to 10 carbon atoms and R' represents an iodinated phenyl linked to the ester oxygen through an alkyl chain consisting of 1 to 3 carbon atoms.
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