52938-70-2Relevant academic research and scientific papers
Asymmetric isomerization of ω-hydroxy-α,β-unsaturated thioesters into β-mercaptolactones by a bifunctional aminothiourea catalyst
Fukata, Yukihiro,Okamura, Takaaki,Asano, Keisuke,Matsubara, Seijiro
supporting information, p. 2184 - 2187 (2014/05/06)
We present a novel methodology for the asymmetric synthesis of β-mercaptolactones via isomerization of ω-hydroxy-α,β- unsaturated thioesters by means of a bifunctional aminothiourea catalyst. The catalyst interacts with the substrate through the cooperati
Preparation and palladium-catalysed cross-coupling reactions of 3-and 4-tributylstannylfuran-2(5H)-ones
Hollingworth, Gregory J.,Perkins, Gemma,Sweeney, Joseph
, p. 1913 - 1919 (2007/10/03)
Stannylfuranones 1 and 2 were prepared by ipso radical desulfurative stannylation of phenylsulfanylfuranones 3 and 16. Compounds 1 and 2 underwent Stille coupling reactions with aryl iodides to give 3- and 4-arylfuran-2(5H)-ones.
Reaction of 4′-nitrobenzenesulfenanilide (NBSA) with Lewis acids. A study of its application in sulfenocyclization of alkenes and alkynes
Benati, Luisa,Capella, Laura,Montevecchi, Pier Carlo,Spagnolo, Piero
, p. 12395 - 12406 (2007/10/02)
Phenylsulfenocyclization of a number of alkenes and alkynes possessing internal hydroxyl, carboxyl or vinyl functionality has been investigated with NBSA. Thioetherification of 4-penten-1-ol 4 as well as thiolactonization of 4-penten-1-oic acid 7 and, to a modest extent, 4-pentyn-1-oic acid 8 can be successfully achieved with NBSA in the presence of boron trifluoride. On the other hand, under analogous conditions 3-buten-1-ol 3 and 3-buten-1-oic acid 6 fail to undergo thiocyclization and give instead oxa- and/or aza-sulfenylation 1,2-adducts. Similar failure is observed with 4-pentyn-1-ol 5, in which case diphenyl disulfide and 4-nitroaniline are the exclusive products. Hexa-1,5-diene 9, to some extent, affords a cyclized arylaminosulfide, i.e. 23, ascribable to formal loss of a methylene unit from the initial (phenylthiomethyl)- cyclopentyl cation 24. The reaction products are discussed in terms of intermediate thiiranium and thiirenium ions whose decomposition mode is strictly dependent upon their structural features. Novel evidence is also presented that aluminium chloride and bromide can promote reaction of NBSA with alkenes and alkynes to afford chloro- and bromo-sulfenylation adducts in varying yields.
Trifluoroacetoxysulphenylation of Unsaturated Nitriles and Transformation of the Adducts into Lactones
Samii, Zakaria K. M. Abd El,Ashmawy, Mohamed I. Al,Mellor, John M.
, p. 2523 - 2532 (2007/10/02)
Reactions of metal acetates with organic disulphides in dichloromethane-trifluoroacetic acid in the presence of unsaturated nitriles give trifluoroacetoxy sulphides, which on hydrolysis readily afford mixtures of the regioisomeric hydroxy sulphides.Optimum yields were obtained with manganese(III)acetate.The mixtures of regioisomeric trifluoroacetoxy sulphides react with acetonitrile under Ritter conditions to give further mixtures of regioisomeric vicinal acetamido sulphides.The regiochemistry of these reactions is discussed.Hydrolysis of the mixtures of trifluoroacetoxy sulphides in aqueous cobalt chloride gives substituted lactones.This high-yield transformation depends upon lactonisation proceeding via an episulphonium ion intermediate; hence conversion of unsaturated nitriles into sulphenyl lactones is characterised by good regiocontrol.
Synthesis of Averufin and its Role in Aflatoxin B1 Biosynthesis
Townsend, Craig A.,Christensen, Siegfried B.,Davis, Steven G.
, p. 839 - 862 (2007/10/02)
Described are two total syntheses of (+/-)-averufin (4) proceeding through a common intermediate and predicated on the efficient introduction of isotopic label(s) at side-chain and nuclear sites for the purpose of biosynthetic investigations of aflatoxin B1 (8).Using these methods, (+/-)--and --averufin, (65) and (68) respectively, and a 1:1 mixture of (+/-)-- and --averufin (71) were prepared and incorporated into aflatoxin B1 using mycelial suspensions of Aspergillus parasiticus (SU-1).In each instance efficient and specific utilization of label was observed in the product by (13)C-n.m.r.spectroscopy, demonstrating the intact incorporation of averufin.When compared with earlier observations of acetate incorporation, a complete correlation of the carbon skeleton from the intermediate anthraquinone stage of the four carbons lost in this overall process were unambiguously identified.In the formation of the dihydrobisfuran, the anthraquinone nucleus migrates to C-2' to branch the linear side-chain of averufin.Deuterium bound at C-1' in averufin is carried to C-13 of aflatoxin.Preparation from (+/-)-averufin (68) of (+/-)--averufin (73) and incorporation of the latter into versiconal acetate (5) demonstrated loss of the terminal two carbons of the averufin side-chain, presumably as acetate, by way of a Baeyer-Villiger-like oxidation.
TRIFLUOROACETOXYSULPHENYLATION OF UNSATURATED NITRILES AS A ROUTE TO LACTONES
Samii, Zakaria K M Abd El,Ashmawy, Mohamed I Al,Mellor, John M
, p. 5293 - 5296 (2007/10/02)
Use of manganic acetate as oxidant permits efficient trifluoroacetoxysulphenylation of unsaturated nitriles with organic disulphides.The adducts in a cobaltous chloride promoted hydrolysis afford alkyl- or aryl-thio substituted lactones.
EXTENDED ENOLATE IONS FROM γ-PHENYLTHIO-CROTONATE ESTERS
Brownbridge, Peter,Hunt, Paul G.,Warren, Stuart
, p. 3391 - 3394 (2007/10/02)
Substituted γ-phenylthio-crotonate esters (7) can be made by and PhS shifts: they form extended enolate anions which react with electrophiles at the carbon atom α to the carbonyl group and γ to sulphur.
The Regiochemistry of A-Ring-labelled Averufin Incorporation into Aflatoxin B1
Townsend, Craig A.,Davis, Steven G.
, p. 1420 - 1422 (2007/10/02)
A-Ring -labelled averufin has been synthesized and found to be incorporated intact into aflatoxin B1, where the labelling pattern in the fused cyclopentenone unequivocally establishes the origin of the carbon backbone as consistent with cur
REGIOSELECTIVE FUNCTIONALIZATION OF THE Δαβ-BUTENOLIDE RING VIA GROUP IV-B ORGANOMETALLICS
Fiorenza, Mariella,Ricci, Alfredo,Romanelli, M. Novella,Taddei, Maurizio,Dembech, Pasquale,Seconi, Giancarlo
, p. 2327 - 2329 (2007/10/02)
The Δα,β-butenolide ring reacts with amino- and thiosilanes to give 4-substituted γ-butyrolactone and siloxyfuran.The latter undergoes regiospecific functionalization at the 5 position with benzaldehyde under F- catalysis.
Synthesis of Butenolides from α-(Phenylthio)-ketones and -esters: Crystal Structure of an Intermediate β-Phenylthio-γ-lactone
Brownbridge, Peter,Egert, Ernst,Hunt, Paul G.,Kennard, Olga,Warren, Stuart
, p. 2751 - 2759 (2007/10/02)
Alkylation of α-(phenylthio)-ketones or -esters with iodoacetate anion gives 1,4-dicarbonyl compounds which are reduced stereoselectively to β-phenylthio-γ-butyrolactones.Oxidation to sulphoxides and thermolysis provides a general synthesis of β- and γ-substituted Δαβ-butenolides.Treatment of 5,5-dimethyl-4-oxo-3-(phenylthio)-hexanoic acid with NaBH4 gives a single γ-lactone whose PhS and But groups are shown to be cis by X-ray crystal structure determination.
