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Butenolides from furans

Extensive studies have been made of the reactions between aldehydes and oxygenated furans most often t-butoxyfurans or trimethylsilyloxyfurans. The products of these condensations lose the oxygen substituent and finish as butenolide (from 2-oxygenated furans) or 3(2//)-furanone (from 3-oxygenated furans) products Schemes 59 <20050L387> and 60 <2003JA1192> show typical examples. [Pg.414]

Butenolides and furanes.6 The [2 4- 2] cycloadducts (3) of alkynes with keten-iminium salts (2), readily formed from 1 (11,560-561), undergo Baeyer-Villiger oxidation to give A ,0-butenolides 4 exclusively. The products are readily reduced to furanes (5) by DIBAH. [Pg.125]

Electrophilic ring closure of alkylidenfuranones of type (76) (A -butenolides), which are available from furan-2-carbaldehyde and y-keto acids, with AICI3 yields 4-arylbenzofuran-6-carboxylic acids (Scheme 70) <77JPR689>. [Pg.376]

Several butenolide natural products of terpenoid origin have been synthesized from furan precursors. On the other hand furan natural products are synthesized from butenolide precursors, e.g. ancistrofuran (133) (Scheme 75). The synthesis of two members of the drimane class of sesquiterpenes containing a butenolide ring have been reported. The first synthesis provides a route to racemic cinnamodial, and the second describes the synthesis of optically active confertifolin (134) from the natural product manool. A rather doubtful mechanism is proposed for the most important reaction in this sequence (Scheme 76). ... [Pg.135]

Butenolides and Tetronic Acids.—An alternative method for the preparation of but-2-en-4-olide itself, in 62—71% yield, from furan employs a mixture of bromine, acetic acid, acetic anhydride, and sodium acetate. ... [Pg.89]

Many examples of natural furans are recorded as having been prepared from five-membered heterocycles such as 2(5H)-furanones (butenolides), which are reduced to furans with diisobutylaluminum hydride. The facile elimination of selenoxides derived from a-phenylseleneyl-y-lactones with formation of endocyclic a,/3-unsaturated butenolides is reported (75JOC542) as a useful route to 2,4- and 2,3,4-substituted furans via their corresponding butenolides. The mixture of dihydrofurans obtained from the tosylhydrazone of tetrahydro-2-furanone (Scheme 88) was oxidized to furans by 2,3-dichloro-5,6-dicyano-l,4-benzoquinone (66CJC1083). [Pg.692]

A concise synthesis of highly substituted furans, pyrroles, butenolides, and 2-butene-4-lactam esters starts from alkynyl adducts of a Fischer carbene complex 21 (Scheme 27) < 1998JOC3164>. Incorporation of an aldehyde yields a reactive vinyl tungstencarbonyl complex 22 that can be oxidatively transformed to an ester group, furnishing the furan carboxylic ester 23. [Pg.513]

Pukalide, a compound isolated from the soft octocoral Sinularia abrupta, is a remarkable natural product with structure 181 containing what amounts to a [4.3] furanophane ring system, one furan ring being in the form of a butenolide group. No synthetic compound is known that even approximates pukalide292 but zexbrevin is a similar 3-furanone obtained from a shrub.130... [Pg.315]

A - -Butenolides are valuable synthetic reagents which constitute the active functionality of many known natural products Recently, the preparation of spiro[cyclopropane-1,5 -furan-2 (5 //)-ones] 2 was reported from the thermal ring contraction of 2-(2-diazoacetyl)cy-clobutanones. [Pg.1049]

Takei utilized a furan as the synthetic equivalent of a 1,4 dicarbonyl compound in his synthesis of pyrenophorin as described in Scheme 4.6. ° Thus butenolide 28, obtained by Michael addition of butenolide 27 to methyl vinyl ketone, was silylated to provide the silyloxyfuran. Treatment with lead tetraacetate followed by aqueous hydrolysis gave 29 in 55% yield. Protection of the ketones as dimethyl ketals followed by selective removal of the C-7 ketal and reduction gave seco acid 30. Dimerization and hydrolysis gave a mixture of 9 and 18 (17% from 29). [Pg.105]

A series of anti-inflammatory hydroxy butenolides was synthesized starting from 55. Thus heating 55 with ethyl phenyl-prop-1-ynoate 141 for 16 h at 210°C afforded 3-phenyl-4-furancarboxylic acid ethyl ester 142 (Fig. 3.42). Functionalization of the ester followed by reaction of the furan ring with singlet oxygen gave the biologically active butenolides, 143. [Pg.440]


See other pages where Butenolides from furans is mentioned: [Pg.399]    [Pg.130]    [Pg.321]    [Pg.321]    [Pg.142]    [Pg.314]    [Pg.45]    [Pg.184]    [Pg.188]    [Pg.233]    [Pg.417]    [Pg.54]    [Pg.140]    [Pg.648]    [Pg.727]    [Pg.365]    [Pg.648]    [Pg.997]    [Pg.179]    [Pg.49]    [Pg.254]    [Pg.277]    [Pg.159]    [Pg.165]    [Pg.190]    [Pg.456]    [Pg.997]    [Pg.130]    [Pg.291]    [Pg.542]    [Pg.343]    [Pg.119]    [Pg.132]    [Pg.305]    [Pg.319]    [Pg.335]   
See also in sourсe #XX -- [ Pg.305 ]

See also in sourсe #XX -- [ Pg.287 ]




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3,4 -3 -butenolid

Butenolides

Butenolides formation from furans

Butenolides furan syntheses from

From furans

Furans butenolides

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