- Asymmetric construction of novel bicyclo[4.4.0] and [4.3.0]ring systems via intramolecular Horner-Wadsworth-Emmons reactions
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Novel perhydro-indanones and -naphthalenones having a quaternary stereogenic carbon and tetrasubstituted olefinic linkage were prepared via asymmetric intramolecular Horner-Wadsworth-Emmons reactions. The optically active binaphthyl phosphonates were conn
- Yamazaki, Jiro,Bedekar, Ashutosh V.,Watanabe, Toshiyuki,Tanaka, Kiyoshi,Watanabe, Joshu,Fuji, Kaoru
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- Desymmetric enantioselective reduction of cyclic 1,3-diketones catalyzed by a recyclable p-chiral phosphinamide organocatalyst
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The P-stereogenic phosphinamides are a structurally novel skeletal class which has not been investigated as chiral organocatalysts. However, chiral cyclic 3-hydroxy ketones are widely used as building blocks in the synthesis of natural products and bioactive compounds. However, general and practical methods for the synthesis of such chiral compounds remain underdeveloped. Herein, we demonstrate that the P-stereogenic phosphinamides are powerful organocatalysts for the desymmetric enantioselective reduction of cyclic 1,3-diketones, providing a useful method for the synthesis of chiral cyclic 3-hydroxy ketones. The protocol displays a broad substrate scope that is amenable to a series of cyclic 2,2-disubstituted five- and six-membered 1,3-diketones. The chiral cyclic 3-hydroxy ketone products bearing an all-carbon chiral quaternary center could be obtained with high enantioselectivities (up to 98% ee) and diastereoselectivities (up to 99:1 dr). Most importantly, the reactions could be practically performed on the gram scale and the catalysts could be reused without compromising the catalytic efficiency. Mechanistic studies revealed that an intermediate formed from P-stereogenic phosphinamide and catecholborane is the real catalytically active species. The results disclosed herein bode well for designing and developing other reactions using P-stereogenic phosphinamides as new organocatalysts.
- Qin, Xu-Long,Li, Ang,Han, Fu-She
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supporting information
p. 2994 - 3002
(2021/03/01)
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- Convenient preparation of synthetically useful chiral quaternary carbon-containing bicyclic compounds with organocatalysts
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Chiral quaternary carbon-containing bicyclic compounds possessing carbonyl functionalities were efficiently synthesized through asymmetric intramolecular aldol reactions with organocatalysts. Bicyclo [3.3.0] and [3.4.0] systems were constructed with a dia
- Kawamoto, Yuichiro,Noguchi, Naoki,Ozone, Daiki,Kobayashi, Toyoharu,Ito, Hisanaka
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supporting information
(2021/11/01)
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- Asymmetric Synthesis of a Bicyclo[43.0]nonene Derivative Bearing a Quaternary Carbon Stereocenter: Desymmetrization of σ-Symmetrical Diketones through Intramolecular Addition of an Alkenyl Anion
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The enantioselective synthesis of a bicyclo[4.3.0]nonene derivative bearing a quaternary carbon stereocenter is achieved by employing a desymmetrization strategy involving an intramolecular addition. The intramolecular nucleophilic addition of a highly reactive carbanion generated from an alkenyl iodide in the presence of a chiral ligand occurs with discrimination of two keto carbonyl groups to give the corresponding bicyclic compound in 81% yield and 39% ee. Asymmetric synthesis via an intramolecular desymmetrization strategy using a chiral ligand-carbanion complex represents a complementary approach to using chiral organocatalysts or chiral ligand-transition-metal complexes.
- Yoshimura, Tomoyuki,Enami, Yuki,Matsuo, Jun-Ichi
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p. 3667 - 3674
(2020/09/07)
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- Stereoselective Reduction of Prochiral Cyclic 1,3-Diketones Using Different Biocatalysts
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We have developed biocatalytic methods for the stereoselective reduction of cyclic prochiral 1,3-diketones for the production of optically active β-hydroxyketones and/or 1,3-diols. The recombinant ketoreductase KRED1-Pglu (formulated as purified catalyst)
- Contente, Martina Letizia,Dall’Oglio, Federica,Annunziata, Francesca,Molinari, Francesco,Rabuffetti, Marco,Romano, Diego,Tamborini, Lucia,Rother, D?rte,Pinto, Andrea
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p. 1176 - 1185
(2019/11/16)
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- Enantio- and Diastereoselective Synthesis of Functionalized Carbocycles by Cu-Catalyzed Borylative Cyclization of Alkynes with Ketones
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A single-pot Cu-catalyzed enantio- and diastereoselective tandem hydroboration/borylative cyclization of alkynes with ketones for the synthesis of carbocycles is reported. The reaction proceeds via desymmetrization and generates four contiguous stereocent
- Zanghi, Joseph M.,Liu, Shuang,Meek, Simon J.
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supporting information
p. 5172 - 5177
(2019/07/03)
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- Silica Support-Enhanced Pd-Catalyzed Allylation Using Allylic Alcohols
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Although allylation using allylic alcohol is an environmentally-friendly method because of water being the sole byproduct in such reactions, allylic alcohol is one of the most difficult allylating agents in Pd-catalyzed allylation of nucleophiles. In this study, we successfully developed a mesoporous silica-supported Pd complex as an efficient catalyst for the allylation of nucleophiles using allylic alcohols as allylating agents. The allylic alcohol is activated by the silanol group on the support surface, which easily undergoes a π-allylpalladium intermediate formation. The catalytic activity of the supported Pd complex was ca. 9 times higher than that of its homogeneous precursor Pd complex. A highest turnover number of 4500 based on Pd was achieved. Various nucleophiles and allylic alcohol derivatives could be used as substrates. Not only the detailed catalyst structure but also the reaction mechanism including the concerted activation of allylic alcohol by the Pd complex and silanol were investigated by several spectroscopic techniques, such as Pd K-edge XAFS, solid-state NMR, and in-situ FT-IR measurements.
- Motokura, Ken,Ikeda, Marika,Kim, Minjune,Nakajima, Kiyotaka,Kawashima, Sae,Nambo, Masayuki,Chun, Wang-Jae,Tanaka, Shinji
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p. 4536 - 4544
(2018/09/21)
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- Method of manufacturing compds. Allylnaphthol
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PROBLEM TO BE SOLVED: To provide a production method of an allyl compound of carrying out the dehydration allylation of a substrate having S, C or N which is a nucleophilic atom, especially S under the presence of a catalyst system consisting of a catalyst precursor having a specific structure and a specific ligand. SOLUTION: The production method of allyl compounds comprises as follow. A catalyst precursor chosen from Formula (1) and Formula (2) and a ligand are mixed, or a catalyst precursor, an allyl alcohol, and a ligand are mixed, then allyl alcohols and a substrate are blended and made to react. The ligand is quinaldic acid or picolinic acid, and the substrate is thiols, thiocarboxylic acids or the like. [Ru(C5H5)(CH3CN)3]PF6(1). [Ru[C5(CH3)5](CH3CN)3]PF6(2). COPYRIGHT: (C)2012,JPOandINPIT
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Paragraph 0064
(2018/06/26)
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- An easy route toward enantio-enriched polycyclic derivatives via an asymmetric domino conjugate reduction-aldol cyclization catalyzed by a chiral Cu(I) complex
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A highly efficient reductive-aldol cyclization mediated by a chiral Cu(I) complex and an organosilane yielded to cyclic or polycyclic derivatives. An excellent control of the selectivities was reached in most cases (dr up to 100:0 and ee up to 95%). After
- Deschamp, Julia,Hermant, Thomas,Riant, Olivier
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experimental part
p. 3457 - 3467
(2012/06/16)
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- A synthetic approach to terpendoles: Decahydrobenzo[f]chromenes by an intermolecular Diels-Alder route
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Synthesis of decahydro-1H-benzo[f]chromene system using intermolecular Diels-Alder reaction has been carried out for the construction of skeleton of terpendole class of terpenoids. ARKAT-USA, Inc.
- Basu, Debjit,Chandrasekharam, Malapaka,Mainkar, Prathama S,Chandrasekhar, Srivari
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scheme or table
p. 355 - 362
(2011/06/09)
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- Enantioselective desymmetrizing palladium catalyzed carbonylation reactions: The catalytic asymmetric synthesis of quaternary carbon center containing 1,3-dienes
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A desymmetrization protocol has been used to develop a palladium catalyzed enantioselective carbonylation process. Achiral cyclic bis-alkenyltriflates are converted to their corresponding monoester derivatives with selectivities of up to 96% ee. The Royal
- Byrne, Simon J.,Fletcher, Anthony J.,Hebeisen, Paul,Willis, Michael C.
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supporting information; experimental part
p. 758 - 760
(2010/06/20)
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- Ruthenium catalyzed selective regio-and-mono-allylation of cyclic 1,3-diketones using allyl alcohols as substrates
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The new ruthenium-sulfonate catalyst Ru(Cp*) (η3-C3H5)(p-CH3C 6H4SO3)2, (Cp*= pentamethylcyclopentadienyl), rapidly and regioselectively mono-all
- Gruber, Stefan,Pregosin, Paul S.
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experimental part
p. 3235 - 3242
(2010/04/28)
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- Efficient construction of polycyclic derivatives via a highly selective cui-catalyzed domino reductive-aldol cyclization
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A versatile methodology for the diastereo-and enantioselective domino reductive-aldol cyclizations is reported. By using a copper (l)/diphosphane ligand, various five-and six-membered rings were generated with good to excellent diastereo-and enantioselect
- Deschamp, Julia,Riant, Olivier
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supporting information; experimental part
p. 1217 - 1220
(2009/10/02)
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- Dioxime oxalates; new iminyl radical precursors for syntheses of N-heterocycles
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Symmetrical and unsymmetrical dioxime oxalates were prepared by treatment of oximes with oxalyl chloride. UV photolysis of these precursors was found to be an atom-efficient way of generating iminyl radicals. The process was most efficient for dioxime oxalates having aryl substituents attached to their C{double bond, long}N bonds. The method was useful for EPR spectroscopic study of iminyl and iminoxyl radicals. Photolyses in toluene solution, of dioxime oxalates containing alkenyl acceptor groups, yielded unsaturated iminyl radicals that ring closed to afford 3,4-dihydro-2H-pyrroles in good yields. Dioxime oxalates with biphenyl substituents also released iminyl radicals that ring closed onto the aromatic acceptor groups and, in acetonitrile solution, this approach provided a useful and atom-efficient method of making substituted phenanthridines.
- Portela-Cubillo, Fernando,Lymer, James,Scanlan, Eoin M.,Scott, Jackie S.,Walton, John C.
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supporting information; experimental part
p. 11908 - 11916
(2009/04/06)
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- Reluctant cross-metathesis reactions: The highly beneficial effect of microwave irradiation
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The beneficial effect of microwave irradiation versus classical thermal conditions is demonstrated through a series of comparative cross-metathesis reactions. Georg Thieme Verlag Stuttgart.
- Michaut, Antoine,Boddaert, Thomas,Coquerel, Yoann,Rodriguez, Jean
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p. 2867 - 2871
(2008/03/14)
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- Asymmetric aza-Wittig reactions: Enantioselective synthesis of β-quaternary azacycles
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A hindrance no more: The direct asymmetric synthesis of nitrogen heterocycles containing β-quaternary stereocenters, widely found for example in alkaloids, is highly challenging. The novel approach shown exploits the desymmetrization of prochiral diketo azides to unmask the asymmetric quaternary center, and represents the first reported examples of the asymmetric aza-Wittig reaction. (Chemical Equation Presented).
- Lertpibulpanya, Duanpen,Marsden, Stephen P.,Rodriguez-Garda, Ignacio,Kilner, Colin A.
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p. 5000 - 5002
(2007/10/03)
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- Concise access to indolizidine and pyrroloazepine skeleta via intramolecular Schmidt reactions of azido 1,3-diketones
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Readily prepared 2-alkyl-2-azidopropylcycloalkyl-1,3-diones undergo intramolecular Schmidt rearrangement with a range of hard Lewis acids, leading to indolizidinediones and pyrroloazepinediones. Chiral aluminium-based Lewis acids could also be used to mediate this symmetry-breaking transformation, but no significant asymmetric induction was observed. The Royal Society of Chemistry 2006.
- Lertpibulpanya, Duanpen,Marsden, Stephen P.
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p. 3498 - 3504
(2008/09/16)
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- Water enables direct use of allyl alcohol for Tsuji-Trost reaction without activators
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(Chemical Equation Presented) An aqueous biphasic reaction system enables the direct use of allyl alcohol in the Tsuji-Trost reaction without the help of any activating reagents for allyl alcohol. The reaction conditions are neutral to basic, allowing the use of amines as the nucleophile. Theoretical calculations have elucidated the importance of hydration of the hydroxy group for the smooth generation of π-allylpalladium species.
- Kinoshita, Hidenori,Shinokubo, Hiroshi,Oshima, Koichiro
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p. 4085 - 4088
(2007/10/03)
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- Stereospecific Synthesis of (+)- and (-)-Cyclooctenone Derivatives Using a Ring Expansion Reaction with Me3SiSnBu3 and CsF
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Novel synthesis of an eight-membered compound by the ring expansion reaction of a two-carbon unit was developed using the stannyl anion generated from Me3SiSnBu3 and CsF in DMF. cis- and trans-cyclooctenone derivatives were synthesized from cyclohexanone derivatives having vinyl iodide in a tether by treatment with Me3SiSnBu3 and CsF in DMF in a stereospecific manner. The trans-cyclooctenone derivative was isomerized to the cis-isomer in the presence of Me3SiSnBu3 and CsF. It is known that the trans-eight-membered ring is an asymmetric compound. Using this procedure, (+)- and (-)-trans-cyclooctenone derivatives could be synthesized from the corresponding optically active cyclohexanone derivatives.
- Imai, Alice Emi,Sato, Yoshihiro,Nishida, Mayumi,Mori, Miwako
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p. 1217 - 1225
(2007/10/03)
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- Asymmetric hydrolysis of pro-chiral 3,3-disubstituted 2,4-diacetoxy-cyclohexa-1,4-dienes
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Asymmetric enzymatic hydrolysis of pro-chiral 3,3-disubstituted 2,4-diacetoxycyclohexa-1,4-dienes 2 affords in high yields optically pure 2,2-disubstituted 3-acetoxycyclohex-3-enones 1 (>98% ee). Under mild conditions Candida cylindracea lipase (enzyme/substrate ratio = 2%) hydrolyses specifically the pro-S enol ester function of the pro-chiral starting material 2.
- Renouf, Philippe,Poirier, Jean-Marie,Duhamel, Pierre
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p. 1739 - 1745
(2007/10/03)
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- A convenient method for selective C-alkylation of 2-methyl-1,3-diketones
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A simple and efficient C-alkylation of 2-methyl-1,3-diketones using a combination of lithium iodide and DBU has been developed.
- Bedekar,Watanabe,Tanaka,Fuji
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p. 1069 - 1070
(2007/10/02)
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- Tetraphenylstibonium Methoxide Promoting C-Alkylation of 2-Substituted Cyclic 1,3-Diketones
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Selective C-alkylation of 2-methyl-1,3-cyclopentanedione and 2-methyl-1,3-cyclohexanedione was performed by using tetraphenylstibonium methoxide (Ph4SbOMe).The presence of a substituent at the 2-position was essential for C-alkylation.
- Fujiwara, Masahiro,Hitomi, Kazuhisa,Baba, Akio,Matsuda, Haruo
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p. 875 - 876
(2007/10/02)
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- Alkylation of cyclic 1,3-diketones
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A simple procedure for the C-alkylation of cyclic 1,3-diketones have been reported using Triton B as base in aqueous conditions.
- Rajamannar,Palani,Balasubramanian
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p. 3095 - 3108
(2007/10/02)
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- Asymmetric Microbial Reduction of Prochiral 2,2-Disubstituted Cycloalkanediones
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Asymmetric microbial reduction of a series of 2,2-disubstituted 1,3-cycloalkanediones with bakers' yeast was examined as an example of an enzyme-catalyzed distinction of a substrate containing two trigonal carbonyl centers with stereoheterotropic faces an
- Brooks, Dee W.,Mazdiyasni, Hormoz,Grothaus, Paul G.
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p. 3223 - 3232
(2007/10/02)
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- CHIRAL CYCLOHEXANOID SYNTHETIC PRECURSORS VIA ASYMMETRIC MICROBIAL REDUCTION OF PROCHIRAL CYCLOHEXANEDIONES
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Microbial reduction of various 2,2-disubstituted-1,3-cyclohexanediones with bakers' yeast provides efficient access to chiral cyclohexanoid synthetic precursors.
- Brooks, Dee W.,Mazdiyasni, Hormoz,Chakrabarti, Sharmistha
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p. 1241 - 1244
(2007/10/02)
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