- The Asymmetric Cyclisation of Substituted Pent-4-enals by a Chiral Rhodium Phosphine Catalyst
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Treatment of the racemic disubstituted pent-4-enals (1) and (2) at ca. 150 deg C with the chiral complex Cl results in a cyclisation reaction and catalytic asymmetric synthesis of the 2,2- and 3,3-disubstituted cyclopentanones (3) and (4), respectively.
- James, Brian R.,Young, Charles G.
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- Enantioselective Intramolecular Hydroacylation of Unactivated Alkenes: An NHC-Catalyzed Robust and Versatile Formation of Cyclic Chiral Ketones
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A highly enantioselective intramolecular N-heterocyclic carbene (NHC)-catalyzed hydroacylation reaction gives access to a range of cyclic ketones from unactivated olefin-substituted aldehydes (up to 99% ee). Remarkably, aliphatic aldehydes were also transformed efficiently in an NHC-catalyzed hydroacylation reaction for the first time. 100% Organic: A highly enantioselective N-heterocyclic carbene (NHC)-catalyzed intramolecular hydroacylation of aromatic and, more interestingly, aliphatic aldehydes with unactivated olefins offers access to a range of cyclic α-chiral ketones bearing quaternary centers. The reaction was found to be highly robust and proceeds with excellent yield in the presence of a diverse range of functional groups.
- Janssen-Müller, Daniel,Schedler, Michael,Fleige, Mirco,Daniliuc, Constantin G.,Glorius, Frank
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supporting information
p. 12492 - 12496
(2015/10/12)
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- COMPOUNDS FOR THE REDUCTION OF β-AMYLOID PRODUCTION
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The present disclosure provides a series of compounds of the formula (I), which modulate β-amyloid peptide (β-ΑΡ) production and are useful in the treatment of Alzheimer's Disease and other conditions affected by β-amyloid peptide (β-ΑΡ) production.
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- Highly efficient and enantioselective α-arylation of cycloalkanones by scandium-catalyzed diazoalkane-carbonyl homologation
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Functionalized α-tertiary and -quaternary 2-arylcycloalkanones are rapidly accessed by scandium(III) triflate-catalyzed diazo-alkane-carbonyl homologations. Recent developments have allowed for carbon insertion reactions to be performed with catalyst loadings as low as 0.5 mol% on scales up to 5 mmol. Pairing readily available bis- and tris(oxazoline) based ligands with scandium triflate allows access to arylated medium ring carbocycles with enantioselectivities up to 98:2 er and >98% yield. The formal C-C insertion of aryldiazo-methanes into unsubstituted cycloalkanones provides a single-step solution to the ongoing challenge of α-arylation. Georg Thieme Verlag Stuttgart · New York.
- Rendina, Victor L.,Kaplan, Hilan Z.,Kingsbury, Jason S.
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experimental part
p. 686 - 693
(2012/04/04)
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- COMPOUNDS FOR THE REDUCTION OF β-AMYLOID PRODUCTION
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The present disclosure provides a series of compounds of the formula (I) which modulate β-amyloid peptide (β-AP) production and are useful in the treatment of Alzheimer's Disease and other conditions affected by β-amyloid peptide (β-AP) production.
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- Catalytic and regioselective ring expansion of arylcyclobutanones with trimethylsilyldiazomethane. Ligand-dependent entry to β-ketosilane or enolsilane adducts
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Divergent reactivity is uncovered in the homologation of arylcyclobutanones with trimethylsilyldiazomethane. With Sc(OTf)3 as catalyst, enolsilanes are obtained with a high preference for methylene migration. By contrast, Sc(hfac)3 g
- Dabrowski, Jennifer A.,Moebius, David C.,Wommack, Andrew J.,Kornahrens, Anne F.,Kingsbury, Jason S.
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supporting information; experimental part
p. 3598 - 3601
(2010/11/04)
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- Tetrahydroquinazolines and dihydrocyclopentapyrimidines as CRF antagonists
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Compounds of the formula (I): and pharmaceutically acceptable salts or prodrugs thereof, wherein m, R1, R2, R3, R4, R5 and R6 are as defined herein. The invention also provides methods for
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Page/Page column 13
(2010/02/10)
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- Mg-promoted mixed pinacol coupling
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Mg-promoted reduction of a mixture of aromatic ketones (or imines) and aliphatic carbonyl compounds in N,N-dimethylformamide (DMF) brought about unique mixed pinacol type of cross coupling to give unsymmetrical vicinal diols (or amino alcohols) or α-hydroxyketones in good to moderate yields. The reaction may be initiated by electron transfer from magnesium metal to an aromatic carbonyl compound possessing a less negative reduction potential. The difference of reduction potential between aromatic ketones (or imines) and aliphatic carbonyl compounds was found to be one of the important key factors in this selective cross coupling.
- Maekawa, Hirofumi,Yamamoto, Yoshimasa,Shimada, Hisashi,Yonemura, Kazuaki,Nishiguchi, Ikuzo
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p. 3869 - 3872
(2007/10/03)
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- Total synthesis of the phenalenone diterpene salvilenone
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The application of a photochemical aromatic annulation strategy in a highly efficient total synthesis of the phenalenone diterpene salvilenone is reported. The pivotal step in the synthesis involves the assembly of the key dihydrophenalene 29 in one step
- Danheiser, Rick L.,Helgason, Anna L.
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p. 9471 - 9479
(2007/10/02)
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- PHOTOLYSIS OF α-DIAZOCYCLOPENTANONES. RING CONTRACTION TO FUNCTIONALISED CYCLOBUTANES AND SYNTHESIS OF JUNIONONE, GRANDISOL AND PLANOCOCCYL ACETATE
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Photolysis of diazoketone 19 in methanol furnished the cyclobutane carboxylate 20.Photolysis in aqueous sodium bicarbonate-THF afforded the acid 21 in better yield.Reduction of the ester followed by oxidation and a subsequent Wittig reaction furnished (+/-) junionone (3).Photolysis of the diazoketone 24 resulted in a 1:1 mixture of cyclobutane carboxylates 25.Treatment of the corresponding carboxylic acids with hydriodic acid furnished the bicyclic lactone 27, a known precursor of grandisol (1).The diazoketone 28, on photolysis yielded a mixture of cyclobutane carboxylates 29 and 30.Conversion of the trans acid 31 to a methyl ketone followed by oxidative functionalisation of the phenyl group gave the keto ester 36 which was isomerised under acid catalysis to 37, which in optically active form had been a precursor to (-) grandisol.Photolysis of diazoketone 38 afforded the cyclobutane carboxylates 39 and 40 in 2:1 proportion.The corresponding mixture of acids on treatment with methyl lithium and subsequent acetylation furnished the keto acetates 43 and 44, resulting in a formal synthesis of planococcyl acetate (4).
- Gosh, Arun,Banerjee, Ujjal K.,Venkateswaran, R.V.
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p. 3077 - 3088
(2007/10/02)
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- A MIMIC STUDY ON COENZYME-B12 USING ORGANOCOBALOXIMES. THE REARRANGEMENT OF 1-SUBSTITUTED-2-OXOCYCLOPENTYLMETHYL RADICAL
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The radical cleavage of the carbon-cobalt bond of 1-phenyl-2-oxocyclopentylmethyl cobaloxime (1) and 1-ethoxycarbonyl-2-oxocyclopentylmethyl cobaloxime (2) gave only 3-phenylcyclohex-2-enone (7) and 3-ethoxycarbonylcyclohex-2-enone (8), respectively, by acyl migration.This rearrangement may be a reasonable mimicry of the ester migration mediated by coenzyme-B12.
- Tada, Masaru,Miura, Kyo,Okabe, Masami,Seki, Shigetaka,Mizukami, Hideyuki
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