3-Buten-4-olides

The cyclofunctionalization of 4-alkynoic and 5-alkynoic acids generates y-alkylidene-y-lactones and 5-alkylidene-S-lactones, respectively (equation 76 and Table 22). The initial products from the reactions catalyzed by mercury or silver salts undergo protiodemetallation under the reaction conditions. The vi-nylpalladium intermediates undergo either protiodemetallation or coupling with an added allyl halide. The palladium(II)-catalyzed cyclization of 3-alkynoic acids proceeds by 5-endo closure to give 3-buten-4-olides (Table 22, entry 2).50 190... 

Die 4-Oxo-4-phenyl-butansaure liefert in Gegenwart von Schwefeltrioxid/Dimethyl-formamid unter Lactonisierung 2-Ethoxy methy kn-4-pheny 1-3-buten-4-olid zu 75°/o10 ... 

The reaction of 4-phenyl-3-buten-4-olide with benzylamine was investigated as a model for polyamide synthesis. Linear polyamides were prepared from ringopening polyaddition of 4,4 -disubstituted bis(3-buten-4-olide) in m-cresol u g aliphatic diamines. Further studies have investigated the production of hydroxy-substituted polyamides from 4,4 -disubstituted bis(4-butanoiide) and polyamide production from 2,2 -p-phenylene bis-oxazolones by similar ring opening reactions with diamines. ... 

Only two members of the series of P,y-unsaturated y-lactones are known today 3-buten-4-olide (59a), identified in cocoa 478) and fried onions (555), and 3-penten-4-olide (59b) (a-angelicalactone), identified in white bread (599), soybeans (557) and raisins 488). 

This reduction can be used to obtain either enantiomer of 4-substituted buten-olides from the corresponding chiral p-keto sulfones (equation I).2... 

The a-alkylidene-y-butyrolactone 3 is isomerized by this method to the buten-olide 4. 

Furan derivatives have been used to inhibit the formation of melanin when combined with other agents <2000JPP2000302642>. For the group consisting of 5-methyl-2(3//)-furanone 86, 2,5-dimethyM-hydroxy-3(2//)-thiophenone, 2-buten -olide, and 2-hydroxymethylfuran 21, the in vitro formation of tyrosinase was inhibited by... 

Related Reagents. a,(3-Butenolide 7-Butyrolactone R)-Pantolactone p-Propiolactone 2-Trimethylsilyloxyfuran p-Vinyl-a,p-buten olide. 

Kvicala, J. Plocar, J. Vlasakova, R. Paleta, O. Pelter, A. 2-Fluoro-2-buten-4-olide, a new fluorinated synthon. Preparation 1,2-, 1,4-and tandem additions. Synlett 1997, 986-988. 

Conjugate reduction of a, -unsaturated carbonyl compounds.1 The HCOOK/ Pd(OAc)2 system is convenient for transfer conjugate reduction of a,f)-unsaturated ketones and esters and of 2-buten-4-olides to the corresponding saturated compounds. The reaction is carried out in DMF at 60° using an excess of HCOOK. 

Conversion of the 2-buten-4-olides (197 R = Me) into the bromomethyl derivative (197 R = CH2Br), followed by oxidation with DMSO, leads to the dioxo compounds (198) (Equation (68)) <84KGS740>. 

Chiral -substituted 4-butanolides. (S)-( + )-2-(p-Tolylsulfinyl)-2-buten-4-olide (2), which can be prepared in several steps from propargyl alcohol (equation 1), is an effective Michael acceptor for stereocontrol led conjugate addition of Grignard reagents. 

Diethoxyphosphinyl-2-buten-4-olide reacts with lithiated dithianes followed by an intermolecular Wittig-Homer reaction to produce fused 7-lactones (equation 37). The reaction of 2-lithio-l,3-di-thianes with nitroarenes gives 2- or 4-[(l,3-dithian)-2 -yl]cyclohexa-3,S(or 2,S-)-diene-l-nitronate compounds (conjugate addition products), free nitroarene radical anions (redox products), 1,3-dithianes and 2,2 -bis( 1,3-dithianes). ... 

In 1986, Keller-Schierlein, ZShner and their respective coworkers isolated ( )-differolide (135, Figure 5.14) from cultures of an actinomycete, Streptomyces aurantiogriseus Tii 3149. This compound ( )-135, whose structure was determined by X-ray diffraction studies, was reported to enhance the formation of aerial mycelium and spores of Streptomyces glaucescens. Especially noteworthy was the fact that the natural product was racemic. There are some examples of the occurrence of racemic and bioactive natural products such as magnosalicin (10) and olean (116), but they are rare. Although there was a straightforward Diels-Alder synthesis of ( )-135 by dimerization of 2-vinyl-2-buten-4-olide, this method would not afford the enantiomers of 135. 

Cerpegin (78) was isolated from Ceropegia juncea and its structure was determined using IR, UV, lH and l C NMR [215] and X-ray crystallography [216]. In a recent synthesis, 78 was obtained in five steps, beginning with a Michael reaction of phenylthioacetonitrile and 2-methoxycarbonyl-4,4-dimethyl-2-buten-4-olide [217]. 

Matsuo and co-workers have described two syntheses of cerpegin (118) (231-233). In the first synthesis, reaction of the lithium salt of phenyl-thioacetonitrile (352) with treated with 2-methoxycarbonyl-5,5-dimethyl-2-buten-4-olide (353) at -78°C and then warmed to room temperature and treated with acid afforded a stereoisomeric mixture of 354 in 93% yield. Oxidation of 354 with mefa-chloroperbenzoic acid followed by reflux in benzene gave 355. Catalytic reduction (Pd-C-HCl) and treatment with base gave 356 in 44% yield. Various methylation procedures were unsuccessful, but reaction with methyl 4-toluene sulfonate in the presence of NaH gave 118 in 81% yield (Scheme 41) (231,232). 

In oiner radikalischen Dissoziationsreaktion wird 2-Methoxy-furan zu Fenten-(2)-l,4-olid und 2-Methyl-buten-(3)-l,4-olid (10-20% d.Th.) als Hauptprodukt umgewandclt8 ... 

Hydrocarboxylation can also be used in the synthesis of heterocycles if the heterofunction is introduced at an appropriate position within the substrate. Thus, preparation of 2,4-disub-stituted 2-buten-4-olides can be achieved via stoichiometric transformation of a protected optically active propargyl alcohol without loss of optical activity30. Sequential treatment with zirconocene chloride hydride (Schwartz s reagent), carbon monoxide, and iodine gives a 55% yield of (S)-2-ethyl-4-isobutyl-2-buten-4-olide30. This reaction resembles the intramolecular hydrocarboxylation of allylic alcohols. 

Cycloaddition. A new trapping partner for the trimethylene-palladium complex is carbon dioxide. 3-Methyl-2-buten-4-olide is formed. A,A -Di-r-butyl-l,2-diaziridinone behaves as a 1,3-dipolar species in the presence of (Ph3P)4Pd and such is trapped by alkenes. ... 

In the volatile fraction of heated glucose, Walter and Fagerson (1968) identified the unsaturated lactone, 2-buten-4-olide (G.7) for the first time in this reaction. In a study of model reactions (see Maillard reaction in Section 3.1), Baltes and Bochmann (1987a) identified G.l, G.7, G.8, G.9 and G.ll (MS data given), among more than 100 monocyclic furans (and ca 350 volatile compounds) in the reactions of serine and threonine with sucrose under conditions similar to coffee roasting. 

G.7) 2(5/f)-Furanone, but-2-eno-4-lactone, 2,5-dihydrofuran-2-one, 2-buten-4-olide, 2-butenoic acid, y-lactone, 4-hydroxy-2-butenoic acid, y-lactone, crotonolactone, isocrotonolactone [497-23-4]... 

G.9) 2(5//)-Furanone, 3,5-dimethyl-, 2-methylpent-2-eno-4-lactone, 2,5-dihydro-3,5-dmethyIfman-2-one, 2,4-dimethyl-2-buten-4-olide J5584-69-0] (S)- 1127418-12-6]... 

G.12) (G.12) 2(5/f)-Furanone, 3-hydroxy-4,5-dimethyl-, 2-hydroxy-3-methylpent-2-eno-4- lactone, 2,5-d hydro-3-hydroxy-4,5-dimethylfuran-2-one, 2-hydroxy-3,4-dimethyl-2-buten-4-olide, sotolon(e) (28664-35-9] FEMA 3634... 

G.13) 2(5/f)-Furanone, 5-ethyl-3-hydroxy-4-methyl-, 2-hydroxy-3-methylhex-2-eno-4-lactone, 5-ethyl-2,5-dihydro-3-hydroxy-4-methylfuran-2-one, 4-ethyl-2-hydroxy-3-methyl-2-buten-4-olide, 2,4-dihydroxy-3-methyl-2-hexenoic acid, 7-lactone, a-hydroxy-p-methyl-Aa,p-7-hexenolactone, abhexone 698-10-2] FEMA 3153 ( )- 1144810-13-9] (/ )- 144831-60-7J (5)- 14483l-61-8]... 

Carbonsaure-anhydride liefern mit Arylessigsauren bzw. Alkoxy-chinonen 2-Buten-4-olide z. B. ... 

Butanolide bzw. 2-Buten-4-olide werden auch aus 3-Brom-propansaure bzw. 3-Brom-acrylsaure liber die durch Halogen-Metallaustausch zuganglichen Anionen mit Carbonyl-Verbindungen erhalten44-48 z.B. ... 

Epoxy-carbonsauren bzw. deren Lactame lassen sich in schwach saurem Medium in Hydroxy-y -lactone bzw. 2-Aminomethyl-2-buten-4-olide umwandeln z.B. ... 

Die Photolyse von Sultonen in Ether ergibt ebenfalls fiber eine Keten-Zwischenstufe 2-Buten-4-olide ... 

Carbonylation of propargyl alcohol 70 in the presence of thiophenol unexpectedly gave rise to 3-(phenylthio)-2-buten-4-olide 71 in high yield [17]. Similarly, 3-(phenyseleno)-2-buten-4-olide 73 was obtained from propargyl alcohol (72) in the presence of diphenyl diselenide [18]. 

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