- Mechanistic Insights into the Formation of δ-Lactones by Cerium-Catalyzed Aerobic Coupling of β-Oxoesters with Enol Acetates
-
δ-Valerolactone derivatives are formed by the cerium-catalyzed, aerobic coupling of β-oxoesters with enol acetates and dioxygen. The products possess a 1,4-diketone moiety, thus, the conversion can be regarded as an Umpolung since the β-oxoesters are oxidized to electrophilic α-radicals. The transformation has similarities to the Baeyer-Villiger oxidation (BVO) where the higher substituted residue migrates. An endoperoxidic oxycarbenium ion comparable to the Criegee intermediate in the BVO is proposed as a reaction intermediate in this case of the oxidative C?C coupling reaction, but in contrast to the BVO, the less substituted alkyl residue migrates. It was demonstrated by the conversion of β-oxoesters with two stereocenters that this 1,2-alkyl shift proceeds with retention of configuration. A radical chain mechanism of the coupling reaction was furthermore evidenced by the conversion of enol acetates and β-oxoesters with cyclopropyl substituents. Isolation and characterization of products with opened cyclopropane rings established the constitution of radical intermediates.
- Christoffers, Jens,Speldrich, Jean-Marico
-
p. 907 - 914
(2021/01/18)
-
- Photoenzymatic Generation of Unstabilized Alkyl Radicals: An Asymmetric Reductive Cyclization
-
Flavin-dependent "ene"-reductases can generate stabilized alkyl radicals when irradiated with visible light; however, they are not known to form unstabilized radicals. Here, we report an enantioselective radical cyclization using alkyl iodides as precursors to unstabilized nucleophilic radicals. Evidence suggests this species is accessed by photoexcitation of a charge-transfer complex that forms between flavin and substrate within the protein active site. Stereoselective delivery of a hydrogen atom from the flavin semiquinone to the prochiral radical formed after cyclization provides high levels of enantioselectivity across a variety of substrates. Overall, this transformation demonstrates that photoenzymatic catalysis can address long-standing selectivity challenges in the radical literature.
- Clayman, Phillip D.,Hyster, Todd K.
-
supporting information
p. 15673 - 15677
(2020/10/18)
-
- NAPHTHYRIDINONE AND PYRIDOPYRIMIDINONE COMPOUNDS USEFUL AS KINASES INHIBITORS
-
Provided are certain PDGFR inhibitors, pharmaceutical compositions thereof, and methods of use thereof.
- -
-
Paragraph 170-171
(2020/05/14)
-
- KINASE INHIBITORS AND USES THEREOF
-
The present disclosure relates generally to compounds and compositions, intermediates, processes for their preparation, and their use as kinase inhibitors.
- -
-
Paragraph 0256; 0304
(2018/12/13)
-
- Asymmetric NaBH4 1,4-reduction of C3-disubstituted 2-propenoates catalyzed by a diamidine cobalt complex
-
A new Co complex of a unique diamidine ligand catalyzes asymmetric NaBH4 reduction of C3-disubstituted (E)- and (Z)-2-propenoates, including C3-oxygen- and nitrogen-substituted substrates with high enantioselectivity. Analysis by X-ray diffract
- Shuto, Yoshihiro,Yamamura, Tomoya,Tanaka, Shinji,Yoshimura, Masahiro,Kitamura, Masato
-
p. 1547 - 1550
(2015/05/27)
-
- COMPOUNDS FOR THE TREATMENT OF CNS DISORDERS
-
The invention relates to novel cycloalkyl- or cycloalkenyl-substituted pyrazolopyrimidinones of formula (I), wherein ā is selected from the group A1 consisting of a C3-C8-cycloalkyl group or a C4-C8-cycloalkenyl group, whereby the members of C3-C8-cycloalkyl group being selected from the group of cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptanyl and cyclooctanyl; and the members of the C4-C8-cycloalkenyl group, being selected from cyclobutenyl, cyclopentenyl, cyclohexenyl, cycloheptenyl, cyclooctenyl, cyclopentadienyl, cyclohexadienyl, cycloheptadienyl, cyclooctadienyl, cycloheptatrienyl, cyclooctathenyl, cyclooctatetraenyl. The new compounds shall be used for the manufacture of medicaments, in particular medicaments for improving perception, concentration, learning and/or memory in patients in need thereof. Chemically, the compounds are characterised as pyrazolopyrimidinones with a cycloalkyl-moiety directly bound to the 1 position of the pyrazolopyrimidinone and a second substituent in the 6 position which is bound via an optionally substituted methylene-bridge. Further aspects of the present invention refer to a process for the manufacture of the compounds and their use for producing medicaments.
- -
-
Page/Page column 39
(2012/05/20)
-
- 1-HETEROCYCLYL-1,5-DIHYDRO-PYRAZOLO[3,4-D] PYRIMIDIN-4-ONE DERIVATIVES AND THEIR USE AS PDE9A MODULATORS
-
The invention relates to novel 1,6-disubstituted pyrazolopyrimidinones, Formula (I) with Hc is a mono-, bi- or tricyclic heterocyclyl group, the ring members of which are carbon atoms and at least 1, preferably 1, 2 or 3, heteroatom(s), which are selected from the group of nitrogen, oxygen and sulphur, which is in the form of -S(O)r - with r being 0, 1 or 2, and - said heterocyclyl group is or comprises 1 non-aromatic, saturated, or partly unsaturated monocyclic ring which comprises at least 1 heteroatom as ring member and - said heterocyclyl group is bound to the scaffold by said 1 non- aromatic, saturated, or partly unsaturated monocyclic ring which comprises at least 1 heteroatom as ring member. According to one aspect of the invention the new compounds are for the manufacture of medicaments, in particular medicaments for the treatment of conditions concerning deficits in perception, concentration, learning or memory. The new compounds are also for the manufacture of medicaments for the treatment of Alzheimer's disease.
- -
-
Page/Page column 163; 167
(2009/10/30)
-
- Novel synthesis of substituted cyclopropane acetic acid ethyl esters from cyclopropyl alkyl ketones
-
The cyclopropane acetic acid ethyl esters 2 have been conveniently prepared in one step from cyclopropyl alkyl ketones 1 by reacting with lead (IV) acetate in triethyl orthoformate in the presence of 70% perchloric acid. In all these reactions triethyl or
- Nongkhlaw, Rishan Lang,Nongrum, Ridaphun,Nongkynrih, Irona,Vattakunnel, Felix Mathew,Myrboh, Bekington
-
p. 1054 - 1057
(2007/10/03)
-
- Novel Preparation of α,β-Unsaturated Aldehydes. Benzeneselenolate Promotes Elimination of HBr from α-Bromoacetals
-
Acetalization, α-bromination, nucleophilic phenylselenenylation, oxidative elimination/hydrolysis was investigated as a novel protocol for the α,β-dehydrogenation of aldehydes. Treatment of acetals with bromine in methylene chloride afforded the corresponding α-bromoacetals in 80-90% yields. Nucleophilic phenylselenenylation was then conveniently effected by treatment with benzenese-lenolate generated in situ in dimethyl sulfoxide from diphenyl diselenide, hydrazine and potassium carbonate. Unbranched α-bromoacetals cleanly afforded substitution products whereas β- and γ-branched ones gave substantial amounts of α,β-unsaturated acetals via formal loss of hydrogen bromide. Oxidative elimination/hydrolysis of these mixtures afforded α,β-unsaturated aldehydes in 50-80% overall yields. In the case of tertiary α-bromoacetals, treatment with benzeneselenolate afforded only dehydrobromination products as mixtures of isomers. The presence of at least a catalytic amount of the organoselenium reagent was found to be crucial for olefin formation. A SET-mechanism, involving benzeneselenolate-induced electron transfer to the halide, loss of bromide ion, and hydrogen atom or proton/electron was proposed for the benzenselenolate-promoted elimination reaction. Experiments designed to trap carbon-centered radicals in intramolecular cyclization or ring-opening reactions failed to provide any evidence for free-radical intermediates.
- Vasil'ev, Andrei,Engman, Lars
-
p. 2151 - 2162
(2007/10/03)
-
- Synthesis and anti-HIV-1 activity of a series of 1-alkoxy-5-alkyl-6- (arylthio)uracils
-
A series of 1-alkoxy-5-alkyl-6-(arylthio)uracils was synthesized and tested for their ability to inhibit HIV-1 replication. Treatment of 2-alkyl- 3,3-bis(methylthio)acryloyl chlorides (5a-e) with AgOCN in benzene followed by reaction of the resulting isocyanates 6a-e with an appropriate alkoxyamine gave N-alkoxy-N'-((2-alkyl-3,3-bis(methylthio)acryloyl)ureas (10a-z) in good to excellent yields. Cyclization of 10a-z in AcOH containing a catalytic amount of p-TsOH produced 1-alkoxy-5-alkyl-6-(methylthio)uracils (11a-z). Oxidation of 11a-z with 3-chloroperoxybenzoic acid in CH2Cl2 resulted in high yields of 1-alkoxy-5-alkyl-6-(methylsulfonyl)uracils (12a-x and 12z) and 1-(benzyloxy)-6-(methylsulfinyl)thymine (12y), which were subsequently reacted with an appropriate arenethiol in ethanolic NaOH solution to afford 1-alkoxy-5-alkyl-6-(arylthio)uracils (14-49). Substitution at the 3- and 5- positions of the C-6-(phenylthio) ring by two methyl groups significantly increased its original anti-HIV-1 activity (EC50: 6-((3,5- dimethylphenyl)thio)-5-isopropyl-1-propoxyuracil (18), 0.064 μM; 6-((3,5- dimethylphenyl)thio)-1-(3-hydroxypropoxy)-5-isopropyluracil (23), 0.19 μM). Among the various alkoxy substituents at the N-1, the propoxy group was the most beneficial for improving the anti-HIV-1 activity. The 1-propoxy derivative 18 proved to be the most potent inhibitor of HIV-1 replication, followed by the 1-(3-hydroxypropoxy) derivative 23. Introduction of an isopropyl group at C-5 of the uracil base also remarkably enhanced the activity. When compound 18 was incubated with a rat liver homogenate preparation, no metabolite was observed, thus confirming the metabolic stability of the N-O bond in these 1-alkoxyuracils.
- Kim, Dae-Kee,Gam, Jongsik,Kim, Young-Woo,Lim, Jinsoo,Kim, Hun-Taek,Kim, Key H.
-
p. 2363 - 2373
(2007/10/03)
-