Efficient synthesis of functionalized 2,5-dihydrofurans and 1,5-dihydro-2H-pyrrol-2-ones by reaction of isocyanides with activated acetylenes in the presence of hexachloroacetone (original) (raw)

Synthesis of 2-Substituted (±)-(2R,3R,5R)-Tetrahydrofuran-3,5-dicarboxylic Acid Derivatives

The Journal of Organic Chemistry, 2001

An efficient synthesis of 2-substituted (()-(2R,3R,5R)-tetrahydrofuran-3,5-dicarboxylic acid derivatives has been developed. Starting from 5-norborne-2-ol, the key intermediate (()-methyl 5,6-exo,exo-(isopropylidenedioxy)-2-oxabicyclo[2.2.1]heptane-3-exo-carboxylate (15) was synthesized in an efficient six-step sequence. The key transformation is the base-catalyzed methanolysis-rearrangement of (()-6,7-exo,exo-(isopropylidenedioxy)-4-exo-iodo-2-oxabicyclo[3.2.1]octan-3-one (14). Further manipulation of the 3-substituent of (()-methyl 5,6-exo,exo-(isopropylidenedioxy)-2-oxabicyclo[2.2.1]heptane-3-exo-carboxylate (15) followed by deprotection of the diol moiety and ring opening catalyzed by RuCl 3 /NaIO 4 gave the title compounds in good yield.

Efficient synthesis of 2,3,4-trisubstituted furans from the reaction of activated acetylenes with ethyl bromopyruvate in the presence of enaminones

Monatshefte für Chemie - Chemical Monthly, 2008

The reaction of dialkyl acetylenedicarboxylates or diaroylacetylenes with ethyl bromopyruvate in the presence of enaminones led to 2-ethyl 3,4-dialkyl 4-bromo-4,5-dihydro-2,3,4-furantricarboxylates or ethyl 3,4-diaroyl-4-bromo-4,5-dihydro-2-furancarboxylate in excellent yields. These compounds are quantitatively converted to the corresponding 2,3,4trisubstituted furans by 4-dimethylaminopyridine.

Synthesis of dihydrofuro[2,3- b ]pyridines by the reaction of 2-amino-4,5-dihydro-3-furancarbonitriles with α,β-unsaturated carbonyl compounds

Journal of Heterocyclic Chemistry, 2002

The reactions of 2-amino-4,5-dihydro-3-furancarbonitriles 1a-d with α,β-unsaturated carbonyl compounds in the presence of sodium ethoxide (0.1 equivalent) gave the corresponding Michael adducts 2a-d, 3a-d and 4a-d. Compounds 2a-d and 3a-c reacted with sodium alkoxide (1 equivalent) to yield the corresponding 7a-alkoxyhexahydrofuro[2,3-b]pyridines 5a-d, 6a-d, 7a-c and 8a-c. Treatment of 5a-d, 6a-d, 7a-c and 8a-c with potassium tert-butoxide produced the corresponding dihydrofuro[2,3-b]pyridines 9a-d and 10a-c. The reaction of 4a-c with sodium ethoxide (1 equivalent) afforded the corresponding dihydrofuro[2,3-b]pyridines 11a-c.

Synthesis of Some Novel 4-(Furan-2-yl)-5,6-dimethylpyridines

in Wiley Online Library (wileyonlinelibrary.com). N-2-amino-4-(furan-2-yl)-5,6-dimethylnicotinonitrile (4) was utilized as key intermediate for the synthesis of some new, pyridopyrimidine, benzo[1,5][g]oxazocine, naphthoquinone, and isoindole derivatives. The structures of the newly synthesized compounds were confirmed by elemental analysis, IR, 1 H-NMR, and mass spectral data.

Synthesis of functionalised furans and pyrroles through annulation reactions of 4-pentynones

Tetrahedron, 1998

A new approach to 4-pentynones through palladium-catalysed coupling reaction of the ready available 2-propynyl ketones with aryl iodides and/or vinyl triflates is proposed. Annulation reactions of both 2-propynyl ketones and 4-pentynones gave functionalised filrans using potassium tert-butoxide in DMF and functionalised pyrroles in the presence of benzylamine or ammonia, respectively in good to high yields. The methodology has been extended to the preparation of 1713-hydroxyandrost-4-en[3,2-b](5methyl)furan and to 1713-hydroxyandrost-4-en[3,2-b](l-benzyl-5-methyl)pyrrole. A different reaction pattem was observed when the 4-pentynones were treated with sodium methoxide in MeOH. The influence of the reaction medium on the outcome of the annulation reaction in the case of one 2-pentyn-1,6-dione (heteroannulation vs. carbocyclization) is also shown.