2-Methoxy-furan

Cycloaddition of 125 with buckminsterfullerene (Ceo) at 3 kbar allowed the adduct [48] to be obtained, preventing a retro Diels-Alder process (Scheme 5.19). Cycloadditions of tropone (125) with furans 134 gave mixtures of 1 1 endo-dcad exo-monocycloadducts 135 and 136, respectively [49a], together with some bisadducts. In this case furan reacts solely as the 27t component in spite of its diene system. Whereas 2-methoxy furan gave mainly the kinetically controlled product 135 (R= OMe Ri =R2 =H), under the same conditions 3,4-dimethoxy furan afforded the thermodynamically controlled cycloadduct 136 (R=H Ri =R2 =OMe) as the major product (Scheme 5.19). 

In 2004, Terada and coworkers reported the first asymmetric phosphoric acid-catalyzed Friedel-Crafts alkylation (Scheme 8). Aldimines 11 reacted with commercially available 2-methoxy furan (20) in the presence of BINOL phosphate (/ )-3q (2 mol%, R = S.S-MeSj-C Hj) to provide access to A-Boc-protected 2-furyl amines 21 in high yields (80-96%) and enantioselectivities (86-97% ee) [19]. 

Scheme 8 Friedel-Crafts alkylation of 2-methoxy furan...

The obtaining of the optically pure (Ss)-26 was achieved in 20% yield by crystallization from the 1 1 mixture of epimers at sulfur resulting from the oxidation of the corresponding thioether. The reaction of (Ss)-26 with 2-methoxy-furan (6 days, 0°C, toluene) afforded only compound 27 (in a complete regio, endo, and 7r-facial selective manner), which was transformed into glyoxalase I inhibitor 28 [42] in a seven-step sequence (Scheme 13). 

Methoxyfurans are not particularly efficient as diene components in cycloadditions to electron-deficient dienophiles, although furan-2,5-dione adds readily to 3-bromo-2-methoxyfuran.85 On the contrary, in 2-methoxy-furan the 2,3-double bond itself possesses an electron-density high enough to enable it to act as a dienophile with an electron-deficient component (e.g., a tetrazine diester).88... 

In 2004 Terada and his group revealed that 2 methoxy furan (45) that can be considered as a vinylketene 0,0 acetal was sufficiently nucleophilic to engage Boc imines 44 in Bronsted acid catalyzed Friedel Crafts type reaction to furnish y aminoalkyl substituted furans 46 in excellent yields and up to 97% ee (Table 5.9) [ 16]. As already explained, phosphoric add 47 protonates the imine, thus generating a chiral contact ion pair the anionic counterion of which controls the enantioselectivity of the C C bond forming event. Although typically 2 mol% ofthe Bronsted acid were... 

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 ... 

HudzikJM, BozzeUi JW. Stmcture and thermochemical properties of 2-methoxy-furan, 3-methoxyfuran, and their carbon-centered radicals using computational chemistry. J Phys Chem A. 2010 114 7984-7995. 

CIC The key components are 2,5-dimethyl-4-methoxy-furan-3(2H)-one with its sugary sweet fruity aroma combined with aromatic fruity p-cymen-8-ol. The floral note is supported by dihydroactinidiolide, 14-cyclotetradecanolide and 16-cyclo-hexadecanolide. 

CIC 2,5-Dimethyl-4-methoxy-furan-3(2H)-one and gamma-nonalactone form the sweet, creamy heart of the profile, surrounded with esters like ethyl caproate, ethyl butyrate, ethyl-2-methyl butyrate and floral, fruity notes like linalool and benzyl acetate. 

These terpene notes are supported by (Z)-3-hexenol, (E)-2-hexenal, (E)-2-hexenol with their fresh, green character. Gamma- and delta-lactones (4-decanolide, 5-decan-olide, 4-dodecanolide, 5-dodecanolide-(Z)-7-decen-5-olide) impart the sweet, creamy, buttery, peach and apricot character. 2,5-Dimethyl-4-hydroxy-furan-3(2H)-one and 2,5-dimethyl-4-methoxy-furan-3(2H)-one are responsible for the sweet creamy fruity body. A bouquet of esters imparts the overall fruity character (mainly esters of ethyl-, (Z)-3-hexenyl and butyl alcohol with acetic-, butanoic-, 2-butenoic, 3-hydroxybutanoic- and hexanoic acid). 

Analogous face-directing effects are also observed with 5-alkoxyfuran-2(5//)-ones. Even with phosphanes of increased steric demand and reduced donor capability, such as tris(2-phenyl-phenyl) phosphite, to modify the nickel catalyst, only low yields and product selectivities are obtained. Whereas complete face selectivity is observed in the reaction of MCP with 5-methoxy-furan-2(5//)-one, a mixture of products arising from proximal 25 and distal 26 ring cleavage of the MCP is formed. 

Dimethyl-A -cyclohexyl-A -methoxy-furan-3-carbonaiiiide — Furmecyclox... 

The oxidation of the cyclic enol ether 93 in MeOH affords the methyl ester 95 by hydrolysis of the ketene acetal 94 formed initially by regioselective attack of the methoxy group at the anomeric carbon, rather than the a-alkoxy ketone[35]. Similarly, the double bond of the furan part in khellin (96) is converted ino the ester 98 via the ketene acetal 97[l23],... 

Benzo[b]furan, trans-2,3-dihydro-2-methoxy-3,5-dimethyl-... 

Benzo[c]furan, 1,3-dihydro-1 -phenyl- H NMR, 4, 574 <75JA5160> Benzo[b]furan-2-carbaldehyde, 3,6-dimethoxy-UV, 4, 589 <71AJC1883> Benzo[b]furan-2-carbaldehyde, 3-methoxy-UV, 4, 589 <73AJC1079>... 

Benzo[b]furan-4,7-dione, 6-methoxy-2-methyl-(acamelin)... 

Furan-2-carbaldehyde, 5-hydroxymethyl- C NMR. 4, 565 <76AJC107) Furan-2-carbaldehyde, 3-methoxy-... 

H NMR, 5, 558 <71BSF990) Furan-2-carbaldehyde, 4-methoxy- H NMR, 4, 558 <7IBSF990) Furan-2-carbaldehyde, 5-methyl- C NMR, 4, 565 (76AJCI07) Furan-2-carbaldehyde, 5-nitro-UV, 4, 588 <50JA753)... 

Furan-2-carboxylic acid, 5-methoxy-, methyl ester UV, 4, 588 <57JOC323)... 

Fu ran-2(3 H)-one, 3-b romo-4-methoxy-dipole moment, 4, 555 B-63MI3I000) Furan-2(3f/)-one, 4,5-dihydro-dipole moment, 4, 555 (B-63MI3I000)... 

Benzo[b]furan, 3-acetoxy-6-methoxy-4-methyl-reactions, 4, 650 Benzo[b]furan, 2-acetyl-oxime... 

Benzo[b]furan, 3-(2-hydroxy-3,5-dichlorophenyl)-5,7-dichloro-properties, 4, 708 Benzo[b]furan, 2-lithio-synthesis, 4, 652 Benzo[i]furan, 3-lithio-ring opening, 4, 79 Benzo[b]furan, methoxy-mass spectrometry, 4, 583 Benzo[b]furan, 6-methoxy-2,3-diphenyl-synthesis, 4, 679... 

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