- Enantioselective synthesis of sabina ketone
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Both enantiomers of sabina ketone were efficiently prepared via an easy synthesis of 1-diazo-5-methylene-6-methylheptan-2-one, starting from succinic anhydride, followed by its highly enantioselective cyclization catalyzed by chiral dirhodium(II) compound
- Barberis, Mario,Pérez-Prieto, Julia
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- Asymmetric Total Synthesis of (-)-Englerin A through Catalytic Diastereo- and Enantioselective Carbonyl Ylide Cycloaddition
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An asymmetric total synthesis of the guaiane sesquiterpene (-)-englerin A, a potent and selective inhibitor of the growth of renal cancer cell lines, was accomplished. The basis of the approach is a highly diastereo- and enantioselective carbonyl ylide cycloaddition with an ethyl vinyl ether dipolarophile under catalysis by dirhodium(II) tetrakis[N-tetrachlorophthaloyl-(S)-tert-leucinate], [Rh2(S-TCPTTL)4], to construct the oxabicyclo[3.2.1]octane framework with concomitant introduction of the oxygen substituent at C9 on the exo-face. Another notable feature of the synthesis is ruthenium tetraoxide-catalyzed chemoselective oxidative conversion of C9 ethyl ether to C9 acetate.
- Hanari, Taiki,Shimada, Naoyuki,Kurosaki, Yasunobu,Thrimurtulu, Neetipalli,Nambu, Hisanori,Anada, Masahiro,Hashimoto, Shunichi
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supporting information
p. 11671 - 11676
(2015/08/11)
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- Synthesis of γ-, δ-, and ε-lactams by asymmetric transfer hydrogenation of N-(tert-butylsulfinyl)iminoesters
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Highly enantiomerically enriched γ- and δ-lactams have been prepared by a simple and very efficient procedure that involves the asymmetric transfer hydrogenation of N-(tert-butylsulfinyl)iminoesters followed by desulfinylation of the nitrogen atom and spo
- Guijarro, David,Pablo, Oscar,Yus, Miguel
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p. 3647 - 3654
(2013/05/22)
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- A simple synthesis of α-methyl-γ-keto acids
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The reaction of the anion derived from α-marpholinonitriles with methyl acrylate in excess of NaH in DMF gives γ-keto acids in high yield. This process is highly convenient for the synthesis of various α-substituted-γ-keto acids, which can be easily converted to naturally occurring α-substituted -γ-lactones.
- Pawar,Waghmare,Lokhande
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p. 2549 - 2551
(2007/10/03)
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- C-nitroso compounds and use thereof
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A C-nitroso compound having a molecular weight ranging from about 225 to about 1,000 (from about 225 to about 600 for oral administration) on a monomeric basis wherein a nitroso group is attached to a tertiary carbon, which is obtained by nitrosylation of a carbon acid having a pKa less than about 25, is useful as an NO donor. When the compound is obtained from a carbon acid with a pKa less than about 10, it provides vascular relaxing effect when used at micromolar concentrations and this activity is potentiated by glutathione to be obtained at nanomolar concentrations. When the compound is obtained from a carbon acid with a pKa ranging from about 15 to about 20, vascular relaxing effect is obtained at nanomolar concentrations without glutathione. The compound is preferably water-soluble and preferably contains a carbon alpha to the nitrosylated carbon which is part of a ketone group. In one embodiment, the C-nitroso compound is obtained by nitrosylation of a conventional drug or such drug modified to modify the carbon acid pKa thereof When such drug is a nonsteroidal anti-inflammatory drug, the resulting C-nitroso compound functions as a COX-1 and COX-2 inhibitor without the deleterious effects associated with COX-1 inhibition but with the advantageous effects associated with COX-1 and COX-2 inhibition. One such C-nitroso compound is a nitrosoketoibuprofen. A specific example of this kind of compound is isolated as dimeric 2-[4′-(α-nitroso)isobutyrylphenyl] propionic acid. In another case, the C-nitroso compound contains the moiety where X is S, O or NR One embodiment is directed to COX-2 inhibitors where a tertiary carbon atom and/or an oxygen atom and/or a sulfur atom is nitrosylated.
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Page column 54
(2010/11/29)
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- An Efficient Approach to β-Oxoadipate Derivatives and γ-Oxo Acids by the Reformatsky Reaction of Ethyl α-Bromoalkanoates with Succinic Anhydride
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Ethyl 2-bromoalkanoates react with zinc and succinic anhydride in dimethylformamide forming 2-substituted 1-ethyl hydrogen 3-oxoadipates (hexanedioates) isolable in a yield of 56 - 78percent.When subjected to decarboxylative saponification, they afford 4-oxoalkanoic acids in overall yields of 50 - 72percent
- Schick, Hans,Ludwig, Ralf
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p. 369 - 370
(2007/10/02)
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- Isomerisation of 2-Alkoxycyclopropanecarboxylic Acids - An Effective Synthesis of 4-Oxo Carboxylic Acids
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(Z/E)-2-Alkoxycyclopropanecarboxylic esters 2/3 were prepared from enol ethers 1 and ethyl diazoacetate.The saponification of these esters gives the corresponding (Z/E)-2-alkoxycyclopropanecarboxylic acids 4/5, which show stereomutation in water/methanol.This isomerisation was studied in labelled solvents and interpreted for the example of (E)-2-methoxy-2-phenylcyclopropanecarboxylic acid (5a).On heating in water/methanol the compounds 4/5 are transformed quantitatively into the corresponding 4-oxo carboxylic acids 6.
- Kunz, Horst,Lindig, Markus
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p. 220 - 229
(2007/10/02)
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- CATALYTIC REDUCTION OF 3-(4,4-DIMETHYL-5-KETO-3-ISOXAZOLE)PROPIONIC ACID AND ITS DERIVATES
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Catalytic hydrogenation of 3-(4,4-dimethyl-5-keto-3-isoxazole)propionic acid (1) in glacial acetic acid in the presence of 5percent palladium on charcoal gives 4-amino-5-methylhexanoic acid (2).Reductions of the corresponding esters, methyl 3-(4,4-dimethyl-5-keto-3-isoxazole)propionate (3) and amide, 3-(4,4-dimethyl-5-keto-3-isoxazole)propionamide (4) afford, however, γ-isopropylbutyrolactam (5).Reductions of 1 and 3 in aqueous acetic acid give 4-keto-5-methylhexanoic acid (6) and methyl 4-keto-5-methylhexanoate (7), respectively.On the other hand amide 4 is converted to2-hydroxy-5-isopropylidene-Δ1-pyrroline (8).Compound 8 is also obtained if 4 is reduced in acetic acid containing a small amount of hydrogen chloride.
- Feuer, Henry,Scholl, Philip C.
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