The intramolecular Diels–Alder reaction: recent advances and synthetic applications

Abstract

, 183 (1984).Recent advances and examples of the intramolecular Diels-Alder reaction are summarized and applications to the total synthesis of natural products, both completed and in progress, noted. A detailed discussion of trienes leading to bicyclo[4.3.0]nonene skeletons is followed by examples of bicyclo[4.4.0]decenes and adducts arising from orthoquinodimethane precursors. Cycloadditions affording bicyclo[n.4.0] systems and bridged-ring adducts from cyclic dienes conclude this survey which is followed by a discussion of unreactive trienes and a brief analysis of synthetic strategy to complete the review. ALEX G. FALLIS. Can. J. Chem. 62, 183 (1984).On rCsume les recents dCveloppements et des exemples de rtaction de Diels-Alder intramolCculaire et on note leur utilisation dans la synthese des produits naturels dCjh effectuCs de m&me que dans celles qui sont en cours. Une discussion dCtaillCe des triknes conduisant aux squelettes bicyclo [Traduit par le journal]

The synthesis of trisubstituted cyclopentadienes and their reactivity in the intramolecular Diels–Alder reaction

“…Thus it appears that the formation of a seven-membered ring in these systems is indeed disfavored. This result is in accord with the results of Bennett o n bis-cyclopentadiene systems (4,8 …”

“…First it was possible that the entropy involved in forming a sevenmembered ring might be too large to overcome, under the reaction conditions employed. There are no carbocyclic examples of substituted cyclopentadienes leading directly to cycloheptanes in the literature, although closely related heterocyclic cases have been reported (4). Secondly the keto-ester will likely be in equilibrium with its enol and, if it adopts the E geometry, then the dienophile is held in a position in which close approach to the cyclopentadiene is not feasible, thus inhibiting cyclization.…”

“…In other trienes the dominating influence of a carbony l function o n the course and stereochemistry of the adducts has been noted due to the desire of the carbonyl function to retain maximum overlap with the neighbouring -rr systems ("carbonyl coplanarity effect") (4,11). These results add to our understanding of this phenomenon and will facilitate the application of these concepts in total synthesis.…”

“…In recent years the intramolecular Diels-Alder reaction has gained widespread popularity in synthetic studies (4). Although a great deal is known about this reaction, there is still much that remains a mystery, particularly the subtle effects of sidechain substituents (5).…”

Intramolecular Diels–Alder reactions of cyclopentadiene systems: Model studies for the total synthesis of the capnellenes

“…Although several detailed studies of the intramolecular Diels-Alder reaction have been undertaken in recent years, many facets are still imperfectly understood and some cycloadditions fail to proceed as anticipated (38)(39)(40). Thus it was considered prudent to examine the initial steps on a model system commencing with 3-methyl-2-cyclopentonone (9).…”