Diels-Alder cycloaddition of 10 followed by Wittig homologation and intramolecular diene cyclozirconation of the resulting triene under equilibrating conditions led to the tricyclic 6-6-5 ketone 5 with high diastereocontrol. The derived alpha-azido ketone 16 cyclized efficiently to the heptacyclic pyrazine core of ritterazine N.

A new synthesis of dibenzopyranones 14 is reported via the Diels-Alder cycloaddition of 4-cyanocoumarins 12 with 1-silyloxydienes 10 to give the adducts 13 which are then converted into 14 in one step via treatment with base and loss of the cyano and silyloxy groups.

C(2)-symmetric bisamidines 8 have been tested as chiral Brønsted bases in the Diels-Alder reaction of anthrones and N-substituted maleimides. High yields of cycloadducts and significant asymmetric inductions up to 76% ee are accessible. The proposed mechanism involves proton transfer between anthrone and bisamidine, association of the resulting ions and finally a cycloaddition step stereoselect...

The general approach of using a bicyclic template to produce inhibitors of the protease superfamily of enzymes has been investigated. The Diels Alder cycloaddition reaction on solid support has been found to be highly efficient for the synthesis of libraries of compounds that mimic the beta-strand secondary structure of proteins. Several potent and selective inhibitors of proteases have been di...

Cycloaddition of 3,4-dibromofuran with azo diesters proceeds by a Diels–Alder reaction followed by a novel rearrangement to give 3,5dibromotetrahydropyridazin-4-ones. Variable-temperature NMR spectroscopy shows four separate conformations at low temperature attributed to restricted rotation about the carbamate functions. The ethyl compound decomposes upon storage with loss of the carbamate grou...

N-Cinnamoyl-9-aminoanthracenes cyclise with PPA or triflic acid to form novel 2-azahexacyclo[10.6.6.0(1,5).0(6,11).0(13,18).0(19,24)]tetracosa-6(11),7,9,13,15,17,19(24),20,22-nonaen-3-ones. In contrast, both N-cinnamoyl-N-methyl-9-(2-aminomethyl)anthracene and N-cinnamoyl-9-(2-aminoethyl)anthracene undergo an intramolecular Diels-Alder cycloaddition.

3,3'-Dicarboxy-4,4'-diaminobiphenyl was synthesized from Onitrobenzoic acid following standard procedures. Diazotization of this compound with isoamylnitrite, under approtic condition gave diphenyl-4,4'-bis-diazonium-3,3'-dicarboxylate and subsequent thermal decomposition of this diazonium compound produced 3,4,3',4'-tetradehydrobiphenyl (bisbenzyne) as a reactive intermediate. Bisbenzyne w...

The Diels–Alder (DA) reaction (or “diene synthesis”) between a diene and a dienophile generates two s bonds stereoselectively and up to four chiral centers in a single step to afford six-membered cyclic compounds. This cycloaddition reaction named after Professor Otto Paul Hermann Diels (1876–1954) and his student Kurt Alder (1902–1958) was discovered in 1928 during studies on the reaction of b...

During the last two decades, organic reactions in aqueous media have been attracting increasing attention. Furthermore, It has been established that some DielsAlder reaction dramatically accelerated in aqueous media. These have been alternatively ascribed to hydrophobic association of the reacting partners, micellar catalysis, solvophobicity, high internal solvent pressure, cohesive energy dens...

Gas-phase reactions of acylium ions with alpha,beta-unsaturated carbonyl compounds were investigated using pentaquadrupole multiple-stage mass spectrometry. With acrolein and metacrolein, CH(3)-C(+)(double bond)O, CH(2)(double bond)CH-C(+)(double bond)O, C(6)H(5)-C(+)(double bond)O, and (CH(3))(2)N-C(+)(double bond)O react to variable extents by mono and double polar [4 + 2(+)] Diels-Alder cycl...