DIELS-ADLER REACTION

Manzamine alkaloids can be isolated from marine sponges. They often contain /3-carboline. This group has a diverse range of bioactivities. It also has its own way of establishing its structures. An intramolecular Diels-Adler reaction for manzamines has been proposed. The a is bisdihydropyridine (derived probably from amonia), and the (3 is intramolecular cycloaddition in a pentacyclic... 

Other linear polymers suitable for high-temperature structural laminates are obtained by the reaction of bis(furfuryl) imide via Diels-Adler reactions (56,57). Stability in air up to 500 °C has been reported for these polymers. The prepolymers have pendent phenyl substituents and are soluble in organic solvents, an important processing improvement for hetero-aromatic polymers. 

The author indicated that in a 1989 Kodak Research Technical Report, with the exception of the diphenylisobenzofuran, dienes used in the Diels-Adler reaction with epoxybutene failed to generate the indicated cycloadducts of the current invention (1). 

Low-yielding Diels-Adler reaction yields have been improved using ionic solvents salts as butyl-3-methyl-l-imidazolium tetrafluoroborate (3). 

Sometimes facilitating reactions are called in by reaction product derivation routines. An example is the change of functionality required to obtain a six membered ring at hand from one which is the product of a plausible Diels-Adler reaction. 

Kamahori K,Tada S, Ito K, Itsuno S (1995) Tetrahedron Asymmetry 6 2547 Kamahori K, Ito K, Itsuno S (1996) J Org Chem 61 8321 Takasu M, Yamamoto H (1990) Synlett 194 Sartor D, Saffrich J, Helmchen G (1990) Synlett 197 Hawkins JM, Loren S (1991) J Am Chem Soc 113 7794 Hawkins JM, Loren S, Nambu M (1994) J Am Chem Soc 116 1657 A modified isopinocampheyldibromoborane catalyzes the reaction of cyclopentadiene with methyl acrylate in 48% ee Bir G, Kaufmann D (1990) J Organomet Chem 390 1 A Lewis acid derived from JY-tosyl tryptophan and l,8-naphthalenediylbis(dichlorobo-rane) is reported to catalyze the Diels-Adler reaction of methacrolein sind cyclopentadiene in 100% ee for the endo isomer (endo/exo = 37 63) ReiUy M, Oh T (1994) Tetrahedron Lett 35 7209... 

Probably, in the first step the double bonds of linoleic acid isomerise to a dienic structure which leads to dimeric acid by a formal Diels-Adler reaction (reaction 17.29). 

Diene A is similar m structure to 1,3-cydohexadiene. which reacts well in Diels-Alder cycloadditions O ablc 14- IX In diene B, however, the ends of the diene are locked in a zigzag conformation (called "s-traas") that puts the end carbons too far apart to bond to the two alkene carbons of a dienophile. Figure 14-9 illustrates how the Diels-Alder reaction involves a diene in a U-shaped conformation (called s-cis ), which puts its end carbons close together. Dienes (like B) that cannot achieve this conformation will not participate with dienophiles in Diels-Adler reactions. 

R. D. J. Proese, S. Humbel, M. Svensson and K. Morokuma IMOMO(G2MS) A new high-level G2-like method for large molecules and its applications to Diels-Adler reactions, J. Phys. Chem. A 101, 227-233 (1997). 

Oppolzer, W., and W. Frostl A stereoselective approach to cis- and transA, 2,3,4,4a, 5,6, 8a-octahydroquinolines by intramolecular Diels-Adler reactions. Helv. Chim. Acta 58, 590—593 (1975). 

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