6838-54-6Relevant academic research and scientific papers
N-heterocyclic carbene-catalyzed asymmetric synthesis of cyclopentenones
Chen, Zhizhou,Kong, Xiangwen,Niu, Shengtong,Yang, Shuang,Liu, Jinggong,Chen, Bolai,Luo, Benlong,Zhou, Changyu,Ding, Chenglin,Fang, Xinqiang
, p. 3403 - 3408 (2021/05/10)
N-Heterocyclic carbene-catalyzed asymmetric construction of cyclopentenones using enals and α-diketones is achieved, furnishing a series of highly functionalized cyclopentenones in a highly diastereo- and enantioselective manner. The protocol tolerates su
Steric Influence on Reactions of Benzyl Potassium Species with CO
Wang, Tongtong,Xu, Maotong,Jupp, Andrew R.,Qu, Zheng-Wang,Grimme, Stefan,Stephan, Douglas W.
supporting information, p. 3640 - 3644 (2021/10/19)
Reactions of benzyl potassium species with CO are shown to proceed via transient carbene-like intermediates that can undergo either dimerization or further CO propagation. In a sterically unhindered case, formal dimerization of the carbene is the dominant reaction pathway, as evidenced by the isolation of ((Ph3SiO)(PhCH2)C)2 2 and PhCH2C(O)CH(OH)CH2Ph 3. Reactions with increasingly sterically encumbered reagents show competitive reaction pathways involving intermolecular dimerization leading to species analogous to 2 and 3 and those containing newly-formed five-membered rings tBu2C6H2(C(OSiR3)C(OSiR3)CH2) (R=Me 6, Ph 7). Even further encumbered reagents proceed to either dimerize or react with additional CO to give a ketene-like intermediates, thus affording a 7-membered tropolone derivative 14 or the dione (3,5-tBu2C6H3)3C6H2CH2C(O))2 15.
Synthesis of maculalactone A and derivatives for environmental fate tracking studies
Bader, Samuel L.,Luescher, Michael U.,Gademann, Karl
, p. 199 - 206 (2015/02/19)
Maculalactone A (1) constitutes a promising antifouling agent, inhibiting the formation of biofilms in marine and freshwater systems. In this study, we developed a new route, based on a late-stage formation of the butenolide core, leading to the total synthesis of maculalactone A (three steps, overall yield of 45%) and delivering material on a gram scale. In addition, analogues of the title compound were assayed concerning their biological activity, utilizing Artemia franciscana and Thamnocephalus platyurus. The most active analogue was functionalized with a rhodamine B fluorophore and was utilized in an in vivo staining experiment in Artemia salina. Two different tissues were found to accumulate this maculalactone A derivative. This journal is
Asymmetric skeletal rearrangement of symmetrically α,α-disubstituted α-amino aldehydes: A new entry to optically active α-hydroxy ketones
Ooi, Takashi,Saito, Akira,Maruoka, Keiji
, p. 3220 - 3221 (2007/10/03)
A unique asymmetric skeletal rearrangement of symmetrically α,α-disubstituted α-amino aldehydes has been accomplished for the first time using a chiral organoaluminum Lewis acid 1. For instance, treatment of (S)-2,2′-bis(trifluoromethanesulfonylamino)-1,1′-binaphthyl with Me3Al (1.0 equiv) in toluene at room temperature for 15 min and at 110 °C for an additional 15 min produced (S)-1, and a subsequent reaction with α -amino aldehyde 2a (R = CH2Ph) at -78 °C for 4 h and at -40 °C for 12 h resulted in the smooth rearrangement to the zwitterionic iminium intermediate A, which furnished the α-hydroxy ketone 3a (R = CH2Ph) in 93% isolated yield with 95% ee (S) after acidic hydrolysis. This result, together with other representative examples, clearly demonstrates the effectiveness of the present method for the hitherto difficult asymmetric synthesis of acyloins. Furthermore, we found that the treatment of the in situ generated A with DIBAH afforded the corresponding anti amino alcohol exclusively without loss of enantiomeric excess. Our approach casts light on the previously unexplored yet potential utility of α-amino aldehydes as synthetic building blocks and also provides a new entry to optically active α-hydroxy ketones and 1,2-amino alcohols. Copyright
Asymmetric acyloin condensation catalysed by phenylpyruvate decarboxylase. Part 2: Substrate specificity and purification of the enzyme
Guo, Zhiwei,Goswami, Animesh,Nanduri, Venkata B.,Patel, Ramesh N.
, p. 571 - 577 (2007/10/03)
Phenylpyruvate decarboxylase from Achromobacter eurydice was used to catalyse the asymmetric acyloin condensation of phenylpyruvate 1 with various aldehydes 2 to produce optically active acyloins PhCH2COCH(OH)R 3. The specific activity of the phenylpyruvate decarboxylase enzyme was increased by a factor of 332 after its purification. The molecular weight of the purified enzyme was shown to be 150 kDa by gel filtration chromatography, while SDS gel electrophoresis showed two sub-units with molecular weights of 90 and 40 kDa. The acyloin condensation yield decreased with increasing chain length for straight chain aliphatic aldehydes from 76% for acetaldehyde to 24% for valeraldehyde. The e.e.s of the acyloin products were 87-98%. Low yields of acyloin products were obtained with chloroacetaldehyde (13%) and glycoaldehyde (16%). Indole-3-pyruvate was a substrate of the enzyme and provided acyloin condensation product 3-hydroxy-1-(3-indolyl)-2-butanone 5 with acetaldehyde in 19% yield, while benzoylformate was not a substrate for the enzyme.
Synthesis of Grevillins, Novel Pyrandione Pigments of Fungi. Biogenetic Interrelationships between Grevillins, Pulvinic Acids, Terphenylquinones and Xylerythrins
Pattenden, Gerald,Pegg, Neil A.,Kenyon, Ronald W.
, p. 2363 - 2372 (2007/10/02)
A synthesis of the grevillin group of pyrandione pigments, e.g. 3, 23 and 24 present in fungi is described.The synthesis, which is based on a biogenetic model, uses bis-benzylacyloins 9 and their corresponding oxalate derivatives as key intermediates (Scheme 3).Treatment of the grevillins 25a-c with sodium ethoxide in ethanol effects their quantitative isomerisation into the corresponding terphenylquinone pigments 4a-c.Perkin-type condensations between the terphenylquinones 4 and arylacetic acids in the presence of sodium acetate-acetic anhydride then produces the xylerythrin pigments 29a-e, whereas rearrangements of 4 in the presence of dimethyl sulphoxide leads to pulvinic acid derivative, e.g. 31, 32 and 5.These synthetic studies interrelate the biosynthetic origins of the pigment types 3, 4, 5 and 8 together with the related pulvinones 6 and furanone 7 fungal pigments.
Pigments of Fungi. XV An Efficient, Unambiguous Route to Unsymmetrically Substituted Dibenzyl Acyloins and their Use in the Synthesis of Fungus Pigments of the Pulvinone and Grevillin Types
Gill, Melvyn,Kiefel, Milton J.,Lally, Deborah A.,Ten, Abilio
, p. 1497 - 1518 (2007/10/02)
Dibenzyl acyloins including those bearing unsymetrically disposed aryl residues are assembled in high yield by reaction between the O-trimethylsilyl ethers of arylacetaldehyde cyanohydrins and benzyl Grignard reagents.These acyloins are deprotonated with
ELECTRON TRANSFER REACTIONS OF ALIPHATIC ESTERS TO THE CORRESPONDING ALIPHATIC KETONES BY LITHIUM 4,4'-DI-T-BUTYLBIPHENYL RADICAL ANION
Karaman, Rafik,Fry, James L.
, p. 4935 - 4938 (2007/10/02)
Sonication of some representative aliphatic esters with lithium in the presence of catalytic amounts of 4,4'-di-t-butylbiphenyl (DBB) in dry THF under N2 afforded the corresponding aliphatic ketones in good yields.Monitoring studies by GC/MS and 1H-NMR spectroscopy after quenching indicate the intermediacy of the corresponding β-ketoesters.
Spectroscopic identification of the nickel acylate complex
Simunic, Joan L.,Pinhas, Allan R.
, p. 1358 - 1360 (2008/10/08)
NMR and IR spectral data of the pentanoyl nickelate complex are presented and are consistent with a mononuclear nickel complex. This nickel acylate complex is thermally stable in THF at ambient temperature (+20°C) for prolonged periods (24 h) but decomposes rapidly in air.
SYNTHESIS OF GREVILLINS AND THEIR BIOGENETIC INTERRELATIONSHIP WITH TERPHENYLQUINONES, XYLERYTHRINS AND PULVINIC ACIDS
Pattenden, Gerald,Pegg, Neil A.,Kenyon, Ronald W.
, p. 4749 - 4752 (2007/10/02)
A synthesis of the grevillin group , of pigments present in fungi, using benzylacyloins, viz (9), as key intermediates is described, and the biogenetic interrelationships between them and the terphenylquinone, xylerythrin and pulvinic acid families of natural colouring matter, are exemplified with the in vitro conversions (16)-(17), (17)-(20) and (17)-(22).
