Partial asymmetric synthesis in the diels-alder reaction

The Diels-Alder condensation of (−)-dimenthyl fumarate with butadiene followed by reduction of the adduct with LiAlH₄, produced (−)-(1R:2R)-4-cyclohexene-trans-1,2-dimethanol in 1–3% optical purity depending on the temperature used to carry out the reaction. However, when AlCl₃, SnCl₄ or TiCl₄ are used to catalyze the reaction then the condensation occurs at much lower temperatures and the product after reduction with LiA1H₄ has the opposite sign and configuration. Furthermore the optical purity of the product ranges from 27–78% depending on reaction conditions. Parameters such as solvent, temperature and catalyst, as they affect asymmetric syntheses, are discussed.     

Tandem hetero diels-alder reaction: synthesis of oxygenated macrocycles

[structure: see text]. C2-symmetric, oxygenated macrocycles have been synthesized from simple acyclic precursors in a single step by a tandem hetero Diels-Alder reaction. Thermolysis and Lewis acid catalysis can effect this novel transformation. The tandem reaction product is formed in preference to the intramolecular cycloaddition product, and an explanation for this result is proposed.     

Control elements in the intramolecular diels-alder reaction: synthesis of α-eudesmol

Triene $\text{1}$ undergoes cyclization with substantial 1,3 and 1,4 chiral induction to give largely trans, equatorial α-eudesmol $\text{3}$.     

Progress toward the total synthesis of cassaine via the transannular diels-alder strategy

The transannular Diels-Alder reaction of trans-trans-trans macrocyclic triene A, bearing two cis substiuents in C(12) and C(13) as well as a gem-dimethyl in C(4), was studied. Under thermal conditions, only the desired trans-anti-cis tricycle B was obtained. This tricycle represents an advanced intermediate toward the total synthesis of cassaine C.     

Type 2 intramolecular N-acylnitroso diels-alder reaction: stereoselective synthesis of bridged bicyclic oxazinolactams

[reaction: see text] The type 2 intramolecular N-acylnitroso Diels-Alder reaction has been employed for the synthesis of substituted bridged bicyclic oxazinolactams. Upon oxidation of hydroxamic acid 6, a 3-benzylated oxazinolactam (7) was synthesized with complete diastereoselectivity. Elaboration of cycloadduct 7 liberated a cis-3,7-disubstituted azocin-2-one (9).     

Asymmetric diels-alder reaction. Cooperative blocking effect in organic synthesis

Remarkably high diastereoselectivity is observed in the organoaluminum catalyzed asymmetric Diels-Alder reaction of (-)-dimenthyl fumarate.     

Medium ring synthesis via intramolecular diels-alder reaction. I. The synthesis of bicyclo[6.4.O]dodecane systems

The regio- and stereocontrolled synthesis of $\text{cis}$-fused bicyclo[6.4.Oldodecane ring systems by the application of the Lewis acid-catalyzed intramolecular Diels-Alder reaction is described.     

Poly-2-vinylfuran,synthesis, characterization,and diels-alder reaction with maleic anhydride

Poly-2-vinylfuran, synthesized by free-radical polymerization of 2-vinylfuran, was characterized by nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy. The pendant furan rings on the polymer backbone were then used as the diene component of a Diels-Alder reaction with maleic anhydride. The juxtaposition of the furan rings at first suggested an “avalanche” Diels-Alder reaction, in which the product of one cyclization would be the reactant of the next. A lack of polymer stereoregularity and the reversibility of the Diels-Alder reaction, however, prevented its formation. On the other hand, when the dienophile was used in a 1:1 molar ratio with respect to furan the smooth reaction produced a new polymer, the maleic anhydride adduct of poly-2-vinylfuran, which characterized by NMR and IR spectroscopy, was air stable and soluble in a number of solvents up to 70% transformation. When heated to 160°C the polymer reverted to maleic anhydride and somewhat decomposed poly-2-vinylfuran.     

A thermal dehydrogenative diels-alder reaction of styrenes for the concise synthesis of functionalized naphthalenes

Functionalized naphthalenes are valuable building blocks in many important areas. A microwave-assisted, intramolecular dehydrogenative Diels-Alder reaction of styrenyl derivatives to provide cyclopenta[b]naphthalene substructures not previously accessible using existing synthetic methods is described. The synthetic utility of these uniquely functionalized naphthalenes was demonstrated by a single-step conversion of one of these cycloadducts to a fluorophore bearing a structural resemblance to Prodan.     

An efficient route to aminoanthraquinones and derivatives via a diels-alder reaction.

Cycloadditions of (E)-1-N-carbobenzoxyamino-1,3-butadiene to naphtoquinones followed by aromatization of the adducts and deprotection of the amino group afford regioselective syntheses of −5 and −8 substituted aminoanthraquinones.     

Structural manifestations of the retro diels-alder reaction

Examination of selected cyclohexene derivatives which are fixed into the boat conformation reveals structural deviations from "normal" C-C bond distances consistent with the early stages of the retro Diels-Alder reaction.     

A convenient synthesis of pyridazine-3,4-dicarboxylic acid by a hetero diels-alder reaction

A convenient route to prepare unsubstituted pyridazine-3,4-dicarboxylic acid on a preparative scale is described. The synthesis involves a hetero Diels-Alder reaction between a new 1,2-diaza-1,3-diene and ethyl vinyl ether and oxidation of the intermediate 1,4,5,6-tetrahydropyridazine as the key step.     

Intramolecular diels-alder reaction of iminothiol esters

Diels-Alder reaction of dienyl α-methacrylthioimidates has been investigated under thermal or Lewis acid or protonic acid catalysed conditions. The utility of the reaction is shown by desulfurative ring contraction of bicyclo[4.4.0] to bicyclo[4.3.0]system.