An effective route to functionalized nicotinamide and isonicotinamide derivatives is described. This involves the reaction of nicotinic or isonicotinic acid with acetylenic compounds in the presence of alkyl isocyanides. The reactive 1:1 intermediates obtained from the addition of alkyl isocyanides to dialkyl acetylenedicarboxylates or dibenzoylacetylene was trapped by OH-acids such as nicotinic or isonicotinic acid to produce dialkyl 2-(alkylamino)-5-[alkyl(3-or 4-pyridylcarbonyl)amino]-3,4-furandicarboxylate, N 3 -(alkyl)-N 3 -[3,4-dibenzoyl-5-(alkylamino)-2-furyl]nicotinamide, and N 4 -(alkyl)-N 4 -[3,4-dibenzoyl-5-(alkylamino)-2-furyl]isonicotinamide derivatives.

Protonation of the reactive intermediate produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates by carboxylic acid leads to vinylphosphonium salts, which undergo nucleophilic reaction with carboxylate anion to produce dialkyl (E)-2-aroyl-2-butenedioate. This intermediate is trapped with isocyanide to produce dialkyl 2-(alkylamino)-5-(aryl)-3,4-furandicarboxylate.

A simple synthesis of dialkyl 2-(alkylamino)-5- [alkyl({2-[4-({alkyl[5-(alkylamino)-3,4-bis(alkoxycarbonyl)-2-furyl]amino}carbonyl)-2-quinolyl]-4-quinolyl}carbonyl)amino]-3,4-furandicarboxylate derivatives is described. This involves reaction of isocyanides, dialkyl acetylenedicarboxylates, and bicinchoninic acid (BCA) in MeCN-THF at 25 °C for 36 hours.

Nucleophilic addition of triphenylphosphine to diesters (II) and subsequent protonation with aromatic carboxylic acids generates vinylphosphonium salts which rearrange and react with isonitriles to give fully substituted furans. -(ALIZADEH*, A.; ROSTAMNIA, S.; ZOREH, N.; OSKUEYAN, Q.; Synlett 2007, 10, 1610-1612; Dep. Chem., Univ. Tarbiat Modarres, Tehran, Iran; Eng.) -Mais 43-107

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