Search

The type 2 intramolecular N-acylazo Diels-Alder reaction has provided a regio- and stereoselective synthesis of bicyclic 1,2-diazine systems. The sequence of transformations has presented a route for the regioselective synthesis of medium-ring nitrogen heterocycles and 1,4-diamines.

A novel and highly diastereoselective method is described for the preparation of polycyclic indole derivatives through the intramolecular imino Diels-Alder reaction of aminoanthraquinone with N-prenylated indole-2-carboxaldehydes in the presence of triphenylphosphonium perchlorate (TPPP). The technique is simple and easy as it initiates from readily available starting substances.

A study was conducted to investigate the double Diels-Alder cycloaddition of two tethered isobenzofurans to the fullerene [C.sub.60]. The method helps to easily perform the saturation of two of the three C=C double bonds within a six-membered ring of [C.sub.60] and provides the means of saturating the remaining double bond of a six-membered ring of [C.sub.60] via the side chains of the isobenzofurans with suitably reactive functional groups.

A study was conducted to examine the reactions of 1,3-disubstituted isobenzofurans with the fullerene [C.sub.60] in the context of an approach to open a large orifice on the fullerene framework. The thermal stability of the adducts toward retro-Diels-Alder fragmentation differs greatly in solution from that in the solid state which suggest that they could be stored at room temperature in the solid state for several weeks without significant decomposition but have to be handled within several hours in solution.

Four novel metal/amine catalysts have converted Boc-NOHO to its acylnitroso species at 5 mol % catalyst loading. These reactions have helped in the preparation of polyfunctional hetero Diels-Alder adducts in high yield and from the commercially available materials.

A new type of cross/coupling/cycloaddition cascade is developed and used in the total synthesis of some members of the hydroxylated phenanthridone subclass of the Amaryllidaceae alkaloid family. The alkaloids are assembled by a one-pot Stille/intramolecular Diels-Alder reactioncascade and the resulting cycloadducts are used for the stereocontrolled installation of other functionality present in the C-ring of the target molecules.

Four novel metal/amine catalysts have converted Boc-NOHO to its acylnitroso species at 5 mol % catalyst loading. These reactions have helped in the preparation of polyfunctional hetero Diels-Alder adducts in high yield and from the commercially available materials.

The hetero Diels-Alder reaction of vinyl allenes and aldehydes in the presence of a Lewis acid is studied both experimentally and theoretically. Theoretical calculations using the density functional theory indicate that the reaction proceeds through a highly asynchronous polar transition state.

A ring-closing metathesis (RCM) mediated, pathway to trifluoromethyl-containing piperidines is detailed, which involves the development of a synthetic route to a new (trifluoromethyl)allylating reagent through a Diels-Alder/retro-Diels-Alder strategy. The findings established that RCM represents a viable pathway to several classes of biologically relevant trifluoromethylated piperidine derivatives.

Total synthesis of two new kempane derivatives were achieved with transannular Diels-Alder reaction (TADA) serving as the key step for the stereoselective formation of tricyclic [6.6.5] system. The synthetic approach also reveals that the geometry of the C3 group of such a tricyclic system plays an important role for the formation of the seven membered kempane skeleton.

A detailed investigation was conducted on the mechanism of enantioselective, hydrazide-catalyzed Diels-Alder cycloaddition. Mechanistic studies using NMR showed the occurrence of a retro Diels-Alder reaction during the catalytic cycle, suggesting a thermodynamic component in the reaction.

A mild, thermal Alder-ene reaction of enalles is developed. The allenic double bond acts as the 'ene' and generates a carbon-carbon bond to an unactivated olefinic 'enophile' in DMF at 120 degree Celsius to give [n.3.0]bicyclic systems (n = 3 -5) in good yields.

The results on the experimental and computational studies of the hydrogen-bond-promoted enantioselective hetero-Diels-Alder reaction of Danishefsky's diene with benzaldehyde are reported. The results indicate that carbonyl group of benzaldehyde is activated by forming an intermolecular hydrogen bond with one of the hydroxyl groups of the alpha,alpha,alpha',alpha'-tetraaryl-1,3-dioxolane-4,5-dimethanol molecule.

The preparation of the symmetrical heptacyclic core of the spiro 6-6-5-5 ritterazines is reported. It is expected that the key Diels-Alder/Wittig/diene cyclozirconation approach illustrated, supported by ZINDO calculations, would be a general strategy for the stereocontrolled construction of polycarbacyclic target structures.

An efficient and rapid synthesis of fluoroalkylated enones, bearing various fluoroalkyl moieties is described. It is concluded that beta-fluoroalkylated enones constitute efficient dienophiles for Diels-Alder cycloadditions and that the presence of the fluorinated moiety both increased the reactivity of these compounds and implied modification of the stereoselectivity.

A highly efficient strategy is developed for the rapid asymmetric synthesis of gem-dimethyl and spirocyclopropyl norbornyl carboxylic acids. The key transformation involved the unprecedented asymmetric Diels-Alder reaction of highly reaction beta,beta-cyclopropyl-alpha,beta-unsaturated N-acyloxazolidinoones with cyclopentadiene affording the adducts in high yield and de.

A gas phase study of substituent effects on the stereochemistry of both intermolecular Diels-Alder (IMDA) reactions of 9-E- and 9-Z-substituted pentadienyl acrylates and intermolecular Diels-Alder (DA) reactions between butadiene and monosubstituted alkenes and 3-substituted acrylates is reported. Cis/trans selectivity for IMDA reactions involving 9-E-substituted pentadienyl acrylates generally follows the normal pattern found for corresponding intermolecular Diels-Alder reactions.

The two complementary procedures for the 'one-pot' synthesis of highly substituted pyridines, one using microwave irradiation as the key technological advance and the second approach based on tethered imine-enamine (TIE) methodology is described. Both routes do not need discrete aromatization step and offer significant advantages over the classical methods giving a wide variety of tri-, tetra-, and penta-substituted pyridines in high optimized yields.

The intramolecular inverse-electron-demand Diels-Alder reaction between imidazoles and 1,2,4-triazines linked by a trimethylene tether from the imidazole N1 position to the triazine C3 proceed in excellent yields to produce 1,2,3,4-tetrahydro-1,5-naphthyridines. The reaction to produce the tetrahydro-1,5-naphthyridines can also be promoted with microwave irradiation.

Research has been conducted on Diels-Alder reactions of phosphaethene with isoprene and 1,3-butadiene. Reaction results have revealed asynchronous transition structures and that the DFT activation energies of these reactions are low.

Research has been conducted on the Diels-Alder adducts between benzoquinones and cyclopentadienes. The reduction of these adducts to the corresponding diols has been carried out and the results demonstrate that the treatment of these diols with acid has produced a skeletal rearrangement reaction.

Research has been conducted on the phosphonoacrolein. The synthesis of the compound performed via the acidic treatment of beta-ethoxy-alpha-(methoxymethyl)vinylphosphonate is described.

Research has been conducted on the Diels-Alder reactions. The kinetics of cyclopentadiene, sorbyltrimethylammonium bromine and sorbyl alcohol reactions with N-substituted maleimides carried out in micellar media has been investigated and the details are reported.

Research has been conducted on anhydrolycorinone. The synthesis of this compound carried out via sequential intramolecular Doels-Alder reactions of the substituted 2-amino-1,3,4-oxadiazole is described.

Research has been conducted on the Diels-Alder reactions. The study of the di-2-azulenylacetylene with tetraphenylcyclopentadienone carried out via autoxidation of the azylenylbenzene derivative to produce 7,8,9,10-tetraphenyldiazuleno[2,1-a:1,2-c]naphthalene is presented.

Research has been conducted on the Diels-Alder reactions. The study of 1-methoxy-4-trimethylsiloxy-1,3-butadiene and o-xylylene regioselective Diels-Alder reactions with arylonitrile carried out via the use of density functional theory is described.

Research has been conducted on the terpenoid lactones isolated from a marine sponge. The results of the Diels-Alder cyclization reaction which has produced tricyclic lactones are reported.

Research has been conducted on the decahydro-as-indacene nucleus of (-)-spinosyn A. The results of the enantioselective and diastereoselective synthesis of this nucleus are presented.

Research has been conducted on Diels-Alder reactions. The catalysis of these reactions by noncovalent synthetic, nucleic acid and protein host binding has been investigated and the details are reported.

Research has been conducted on the Diels-Alder reaction. The route to the spiro[2.4]hepta-4,6-diene-4-carboxylic acid esters and spiro[2.4]hepta-4,6-diene-4-methanol has been developed via the use of the hetero-Diels-Alder reaction and the utilization of these dienes for the rac-10-hydroxycamphor synthesis via carbo-Diels-Alder reaction has been carried out.

Research has been conducted on the chiral cyclic vinyl sulfilimines. The reactivity of these compounds as dienophiles in [4+2] cycloaddition reactions with furan and cyclopentadiene as model dienes has been investigated and the results are reported.

Research has been conducted on the sulfilimine. The dienophilic behavior of this sulfilimine has been investigated in its Diels-Alder reactions with acyclic dienes and furans and the results are reported.

Research has been conducted on the cyclohexenone Diels-Alder intramolecular reaction. Results indicate that this reaction has afforded tricyclo[4.3.1.0 (super)3,7]decanon under TMSCl-NEt (sub)3 -ZnBr (sub)2 conditions.

Research has been conducted on the asymmetric carbon-carbon formation, Diels-Alder, Michael, and aldol reactions. The synthesis of the planar chiral 1,3-oxazol-2(3H)-one and its applications in asymmetric carbon-carbon bond formation are described.

Research has been conducted on the intramolecular Diels-Alder reaction. The thermolysis of dienals prepared in the presence of zinc metal with ethyl 2-bromo-methylacrylate has produced tricyclic cycloadducts in the intramolecular Diels-Alder reaction.

Research has been conducted on the carbohydrate-based tetrahydropyridazines. The preparation of these compounds via the hetero-Diels-Alder reaction of 1,2-diaza-1,3-butadienes with acrylonitrile is described.

Research has been conducted on the hetero-Diels-Alder reaction of aldehydes with Danishefsky's diene. The role of the chiral Lewis acids in this reaction has been investigated and the results indicate that the effective catalyst for the reaction is Ti(IV)-H (sub)8-BINOL complex.

Results suggest that in the hetero-Diels-Alder and cheletropic cycloaddition of (E)-1-methoxybutadiene and SO(sub)2, the Diels-Alder reaction does not form stable sultines but forms sulfolene as determined by proton-nuclear magnetic resonace spectroscopy. Data indicate that the cheletropic addition exhibits a pseudo-first-order kinetics and the solvation number for the transition structures is three or more.

Research has been conducted on the Diels-Alder reactions of quinocrown and quinobenzocrown ethers with cyclopentadiene. The catalysis of these reactions carried out via the addition of alkali, ammonium perchlorates, alkaline earth metal and scanium trifluoromethane-sulfonate is described.

Research has been conducted on 1-oxa-4-thia-6-vinylspiro[4.5]dec-6-ene, 3-methoxy-3-methyl-2-vinylcyclohexene, and 3-methoxy-2-vinylcyclohexene. The facial selectivities of Diels-Alder cycloadditions of dienophiles to these compounds have been investigated and the results indicate the reduced syn-to-oxygen dienophile addition.

Research has been conducted on the chiral perhydro-1,3-benzoxazines. Results indicate that the intramolecular Diels-Alder reactions on these benzoxazines derived from (-)-8-amino methanol occur with high stereoselection and in high yields.

Research has been conducted on the asymmetric synthesis of the (6R,7S)-7-tert-butoxycarbonylamino-2-ketocarbacepham. The use of the hetero Diels-Alder reaction of the benzylimine with Danishefsky's diene is described.

Research has been conducted on the Diels-Alder cycloadditions of 3,5-dibromo-2-pyrone. The investigation of these cycloadditions has been carried out via the use of the electronically and sterically distinct dienophiles and the results indicate that this compound is a highly potent ambident diene capable of generating bicycloadducts in high chemical yields.

Research has been conducted on the optically active 2-alkoxy-2H-pyran-3(6H)-ones. The synthesis of these compounds has been carried out via the tin(IV) chloride promoted glycosylation and prepared from D-xylose and rearranged 2-acetoxy-3,4-di-O-acetyl-D-xylal and the absolute configuration of the new stereocenter at C-2 has been determined via the chemical transformation of the dihydrophyranones into the alkyl pentopyranosides.

Research has been conducted on the 5-hydroxy-4-hydroxymethyl-2-cyclohexenylguanine. The facile synthesis of this compound has been carried out and the involvement of the Diels-Alder reaction of ethyl (2E)-3-acetyloxy-2-propenoate with Danishefsky's diene in building up the ring skeleton is reported.

Research has been conducted on the catalyzed Diels-Alder reaction of alkylidene- or aryldeneacetoacetates and Danishefsky's dienes with lanthanide salts. Results indicate that this reaction has produces corresponding carbocyclic adducts.

Research has been conducted on the Diels-Alder reactions. The experimental kinetic data for these reactions have been investigated and the results demonstrate why a 5 LiClO (sub)4 -diethyl ether solution offers reaction rate, endo/exo ratio and yield enhancement.

Research has been conducted on the (+)-hatomarubigin. The synthesis of this compound has been carried out and the results are described.

Research has been conducted on the alpha-aryl-beta-monohalo-alpha-nitrosoethylenes. The reactions of these compounds with the selected dienes have been investigated and the results are reported.

Research has been conducted on the 1,2-di(6-azulenyl)pentaphenylbenzenes and (6-azulenyl)tetraphenylbenzenes. The synthesis of these compounds has been carried out via the Diels-Alder reactions of di(6-azulenyl)acetylenes and 6-(phenylethynyl)azulenes with the tetraphenylcyclopentadienone and the results are reported.