Furan, 2-methyl cycloaddition reactions

Furan, 2,3-dihydro-5-methyl-polymers, 1, 276 Furan, 2,3-dihydro-3-methylene- H NMR, 4, 577 Furan, 2,5-dihydro-2-methylene- H NMR, 4, 577 tautomerism aromaticity and, 4, 595 Furan, 2,5-dihydro-2-nitro-structure, 4, 550 Furan, 2,3-dihydroxy-tautomerism, 4, 37 Furan, 2,4-dihydroxy-tautomerism, 4, 37 Furan, 3,4-dihydroxy-tautomerism, 4, 37 Furan, 2,5-diiodo-nitration, 4, 602 synthesis, 4, 712 Furan, 3,4-diiodo-reactions, 4, 650 Furan, 2,3-dimethoxy-synthesis, 4, 625, 648 Furan, 2,5-dimethoxy-synthesis, 4, 648 Furan, 3,4-dimethoxy-cycloaddition reactions, 4, 64, 625 lithiation, 4, 651 reactions... 

Benzo[c]furans (isobenzofurans) are very reactive but generally unstable dienes which are prepared in situ and trapped. The in ihu-generated isobenzo-furan 33 was trapped by cycloaddition reaction with bis(methyl (S)-lactyl) ester 34 to afford [32] optically active naphthols (Equation 2.12). The cycloaddition was carried out in the presence of a catalytic amount of glacial acetic acid and represents a facile one-pot procedure to synthesize substituted naphthols. 

Both uncatalyzed and catalyzed [4+2]-cycloaddition reactions of furans with the allenic esters have been reported (Table 12.6) [93]. The allene adds from the less hindered C1-C2 Jt-face. The unfavorable steric interaction between the a-hydrogen atom of the furan and the methyl group at C4 of the allene is responsible for this selectivity. The more reactive 2-methylfuran adds to the allenic ester also in a regio-selective manner. The C2 carbon atom of 2-methylfuran was exclusively attached to the Cl carbon atom of the allenic ester, providing a mixture of endo- and exoadducts. 

Gowravaram and Gallop (169) adapted the rhodium-catalyzed generation of isomiinchnones from diazo imides to the solid-phase synthesis of furans, following a 1,3-dipolar cycloaddition reaction with alkynes. A variety of furans were prepared in this fashion. With unsymmetrical electron-deficient alkynes (e.g., methyl... 

Hydrolase-catalyzed domino reactions incorporating a resolution and a subsequent cycloaddition reaction have been described [95-97]. This constitutes an attractive approach to complex synthetic intermediates. For example, the l-(3-methyl-2-furyl)]propanol roc-93 reacts with ethoxyvinyl methyl fumarate (94) catalyzed by Lipase LIP (from Pseudomonas aeruginosa) to furnish a dienophilic fumarate ester, which spontaneously undergoes an intramolecular Diels-Alder reaction with the furan moiety furnishing exclusively the syn-adduct, the oxabicy-clohexene 95 in excellent along with the remaining alcohol S-96 (Scheme 4.31) [95]. A similar approach has been used for a procedure that includes a series of domino reactions that includes dynamic kinetic resolution of the 3-vinylcyclohex-... 

A review of intramolecular 4 + 3-cycloadditions of allyl cations has been presented.277 The 4 + 3-cycloaddition reaction of C(2)-substituted furans with 1,3-dimethyloxyallyl cations show high endo diastereoselectivity and a cis dia-stereospecificity.278 The tandem Peterson olefination/[4 + 3]-cycloaddition of tertiary alcohols (149) in the presence of filran and Lewis acids (TiCLt) furnishes cycloheptanes (150) in modest yields (Scheme 57).279 (Trimethylsilyl)methyl allylic sulfones (151) were used to investigate the scope and limitations of intramolecular 4 + 3-cycloadditions of allylic sulfones (Scheme 58).280 Lewis acid-catalysed 4 + 3-... 

Furan, 2-(p-hydroxyphenyI)-2,5-dihydro-synthesis, 4, 677 Furan, 3-hydroxytriphenyl-tautomerism, aromaticity and, 4, 595 Furan, iodo-synthesis, 4, 712 Furan, 2-iodo-Grignard reagents, 4, 79 Furan, 5-iodo-2-nitro-synthesis, 4, 711 Furan, 2-isopropyl-cycloaddition reactions with ff, ,a, ff -tetrabromoacetone, 1, 418 Furan, 2-lithio-5-methyl-synthesis, 1, 419 Furan, 2-mercapto-tautomerism, 4, 38 Furan, 3-mercapto-tautomerism, 4, 38 Furan, methoxy-planarity, 4, 544 synthesis, 4, 664 Furan, 2-methoxy-synthesis, 4, 648 Furan, 3-methoxy-Diels-Alder reaction, 1, 416 synthesis, 4, 649... 

---