- Methyl homologues of methyl jasmonate and methyl dihydrojasmonate (Hedione) from sorbyl alcohol
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Treatment of cycloalkanone dimethyl acetals 3-6 with sorbyl alcohol (=(2E,4E)-hexa-2,4-dien-1-ol; 1) in the presence of acids afforded the novel cycloalkenones 8, 9, 11, and 13 via a domino reaction (Claisen rearrangement with intramolecular ene reaction and retro-ene reaction). Cyclopentenone 8 was readily transformed into 14 and 15, methyl homologues of racemic methyl jasmonate (16) and methyl dihydrojasmonate (= Hedione; 17), respectively. The organoleptic properties of 14 and 15 are also discussed.
- Giersch, Wolfgang,Farris, Iris
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- Crystal and molecular structure of the symmetrical bidentate ligand 3,3-di(1-pyrazolyl)pentane, CH3CH2C(C3H3N2)2CH2CH3
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The title compound crystallizes in the centrosymmetric space group C2/c with a = 14.4005(23), b = 7.0494(12), c = 11.2462(20) A, β = 101.572(13)° and Z = 4; the molecule lies on a crystallographic C2 axis. Hydrogen atoms were both located and refined.
- Churchill, Melvyn Rowen,Churchill, David George,Huynh, My Hang Vo,Takeuchi, Kenneth J.,Distefano, Alison J.,Jameson, Donald L.
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- Ecofriendly fast batch synthesis of dioxolanes, dithiolanes, and oxathiolanes without solvent under microwave irradiation
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2,2-Dimethoxypropane and 3,3-dimethoxypentane react with 1,2-ethanediol, thio, and oxathio analogues to give the corresponding protected carbonyls in high yield under mild solvent-free conditions. These environmentally benign conditions under microwave irradiation are applied to a large-scale synthesis.
- Perio, Bertrand,Dozias, Marie-Joelle,Hamelin, Jack
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Read Online
- Photocatalytic Reductive Formation of α-Tertiary Ethers from Ketals
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A general photocatalytic reductive strategy for the construction of unsymmetrical α-tertiary dialkyl ethers is reported. By merging Lewis acid-mediated ketal activation and visible-light photocatalytic reduction, in situ-generated α-alkoxy radicals were found to engage in addition reactions with a variety of olefinic partners. Good reaction efficiency is demonstrated with a range of ketals of aromatic and aliphatic ketones. Extension to acetal substrates is also described, demonstrating the overall synthetic utility of this methodology for complex ether synthesis.
- Rossolini, Thomas,Ferko, Branislav,Dixon, Darren J.
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supporting information
p. 6668 - 6673
(2019/09/03)
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- Design of chemically stable, potent, and efficacious MDM2 inhibitors that exploit the retro-mannich ring-opening-cyclization reaction mechanism in spiro-oxindoles
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Inhibition of the MDM2-p53 protein-protein interaction is being actively pursued as a new anticancer therapeutic strategy, and spiro-oxindoles have been designed as a class of potent and efficacious small-molecule inhibitors of this interaction (MDM2 inhibitors). Our previous study showed that some of our first-generation spiro-oxindoles undergo a reversible ring-opening-cyclization reaction that, from a single compound in protic solution, results in an equilibrium mixture of four diastereoisomers. By exploiting the ring-opening-cyclization reaction mechanism, we have designed and synthesized a series of second-generation spiro-oxindoles with symmetrical pyrrolidine C2 substitution. These compounds undergo a rapid and irreversible conversion to a single, stable diastereoisomer. Our study has yielded compound 31 (MI-1061), which binds to MDM2 with Ki = 0.16 nM, shows excellent chemical stability, and achieves tumor regression in the SJSA-1 xenograft tumor model in mice.
- Aguilar, Angelo,Sun, Wei,Liu, Liu,Lu, Jianfeng,McEachern, Donna,Bernard, Denzil,Deschamps, Jeffrey R.,Wang, Shaomeng
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p. 10486 - 10496
(2015/02/19)
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- Catalytic asymmetric phase-transfer reactions using tartrate-derived asymmetric two-center organocatalysts
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A new highly versatile asymmetric two-center catalyst, tartrate-derived diammonium salt (TaDiAS), was designed and a catalyst library containing more than 70 new two-center catalysts was constructed. A variety of (S,S)- and (R,R)-TaDiAS were easily synthesized from diethyl L- and D-tartrate, respectively, using common and inexpensive reagents under operationally simple reaction conditions. TaDiAS was used in phase-transfer alkylations and Michael additions to afford various optically active α-amino acid equivalents in up to 93% yield. Moreover, dramatic counter anion effects were observed in phase-transfer catalysis (PTC) for the first time, making it possible to further improve reactivity and selectivity. These findings validate the usefulness of three-dimensional fine-tuning of the catalyst (acetal, Ar, and counter anion) for optimization. Recovery and reuse of the catalyst was also possible using simple procedures. The present asymmetric PTC was successfully applied to enantioselective syntheses of serine protease inhibitor aeruginosin 298-A and its analogues.
- Ohshima, Takashi,Shibuguchi, Tomoyuki,Fukuta, Yuhei,Shibasaki, Masakatsu
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p. 7743 - 7754
(2007/10/03)
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- 4-chloro-3,5-dimethyl-2-sulfonyl pyridines
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2-Sulfonylpyridine derivatives can be industrially produced efficiently by reacting a sulfonyl cyanide derivative with an α,β-unsaturated carbonyl compound and a 2-{[(2-pyridyl)methyl]thio}-1H-benzimidazole skeleton can be formed in one step in a good yield by reacting this type of the 2-sulfonylpyridine derivative with a 2-methylthio-1H-benzimidazole derivative in the presence of an organolithium compound.
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Referential example 2
(2010/11/29)
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- An inexpensive carbohydrate derivative used as a chiral auxiliary in the synthesis of α-hydroxy carboxylic acids
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Protected α-hydroxy carboxylic acids were synthesized in moderate yield and high diastereoselectivity by alkylation of glycolate (α-hydroxy acetate) enolates using a D-fructose-derived chiral auxiliary. The new chiral center was assigned the R configuration based on comparisons of optical rotations and on one crystal structure analysis. This alkylation methodology is compatible with several hydroxyl protecting groups. The free hydroxy acids were obtained upon removal of the protecting group from the hydroxyl functionality followed by saponification.
- Yu, Hongwu,Ballard, C.Eric,Boyle, Paul D,Wang, Binghe
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p. 7663 - 7679
(2007/10/03)
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- Catalytic asymmetric epoxidation
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A compound and method for producing an enantiomerically enriched epoxide from an olefin using a chiral ketone and an oxidizing agent is disclosed.
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Page column 52
(2010/01/30)
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- Method for producing 2-sulfonylpyridine derivatives and method for producing 2-{[(2-pyridyl)methyl]thio}-1H-benzimidazole derivatives
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2-Sulfonylpyridine derivatives can be industrially produced efficiently by reacting a sulfonyl cyanide derivative with an α, β-unsaturated carbonyl compound and a 2-{[(2-pyridyl)methyl]thio}-1H-benzimidazole skeleton can be formed in one step in a good yield by reacting this type of the 2-sulfonylpyridine derivative with a 2-methylthio-1H-benzimidazole derivative in the presence of an organolithium compound.
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- Investigation of the Effects of the Structure and Chelate Size of Bis-oxazoline Ligands in the Asymmetric Copper-Catalyzed Cyclopropanation of Olefins: Design of a New Class of Ligands
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A set of novel, C2-symmetric bis-oxazoline ligands has been synthesized by mounting two oxazoline rings onto an optically active 1,3-dioxolane backbone. This design allows for the control of both orientation as well as the proximity of the oxazolinyl R-groups around the reactive site. As a result of the twist imparted by the 1,3-dioxolane ring, the stereogenic oxazolinyl substituents can be brought either toward or away from the complexed metal in a controllable fashion. Starting from L-amino alcohols and either L- or D-tartaric acid, two sets of ligands (6b-e and 7a,b) were synthesized and evaluated in the copper-catalyzed cyclopropanation of olefins. The comparison of benzyl and isopropyl derivatives of these ligands with previously reported five- and six-membered bis-oxazolines clearly indicates the beneficiary effect of the larger chelate size and the chiral tether of the tartrate-derived ligand. The effect of the different oxazolinyl groups along with the different substituents on the dioxolane tethers was also investigated. The influence of the alkyl group of the diazoacetate was studied, and the diazoacetate derived from (-)-8-phenylmenthol was found to be superior to (-)-menthyl diazoacetate. The cyclopropanation of vinyl acetate, a relatively unexplored substrate for this reaction, furnished cyclopropanol derivatives in good optical purity.
- Bedekar, Ashutosh V.,Koroleva, Elise B.,Andersson, Pher G.
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p. 2518 - 2526
(2007/10/03)
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- 2,3-O-(3-pentylidene)-D-glyceraldehyde and 2,3-O-(3-pentylidene)-L-glyceraldehyde: Convenient glyceraldehyde surrogates obtained via a novel periodate-based oxidation system
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The synthesis of two novel glyceraldehyde surrogates, 2,3-O-(3-pentylidene)-D-glyceraldehyde (2) and 2,3-O-(3-pentylidene)-L-glyceraldehyde (3) is presented. Synthesis, handling and storage advantages of 2 and 3 over the conventionally employed 2,3-O-isopropylidene-D-glyceraldehyde (1) are discussed. The 3-pentanone-derived protecting group facilitates the extraction of product from aqueous oxidation solutions, while the 3-pentanone liberated on ketal deprotection can be efficiently removed at reduced pressures. The synthesis employs a buffered potassium periodate oxidation which offers significant advantages over sodium periodate in glycol cleavage reactions.
- Schmid,Bradley
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p. 587 - 590
(2007/10/02)
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- Halogenative Deoxygenation of Ketones; Vinyl Bromides and/or gem-Dibromides by Cleavage of 1,3-Benzodioxoles (Ketone Phenylene Acetals) with Boron Tribromide
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Representative ketones 1 have been converted in generally good yields to the respective 1,3-benzodioxoles 5 by trans-acetalization of ketone dimethyl acetals with 1,2-dihydroxybenzene, and cleaved with boron tribromide. 1,3-Benzodioxoles derived from α-unbranched aliphatic ketones gave in general a mixture of vinyl bromides and gem-dibromides; pure gem-dibromides could be selectively obtained in most of cases using a suitable reaction time. 1,3-Benzodioxoles derived from α-branched ketones gave complex mixtures and their cleavage appears to be of little synthetic signifance. 1,3-Benzodioxoles of aromatic ketones gave vinyl bromides only.Aliphatic cyclic gem-dibromides 3 were converted to the respective vinyl bromides 2 by phase-transfer-catalysed dehydrobromination.
- Napolitano, Elio,Fiaschi, Rita,Mastrorilli, Ettore
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p. 122 - 125
(2007/10/02)
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