Utility of a chiral 1,3-dioxane template in stereoselective intramolecular Diels-Alder reactions

The ethylidene acetal of d-erythrose was used as a template for stereoselective IMDA reactions: high endo selectivity and yields in favor of the cis product were observed with 1,3,9-trienes, resulting from a boat transition state. For natural product synthesis, the reaction was successfully applied to a diene with terminal Z-olefin.     

Expedient stereoselective synthesis of coronafacic acid through intramolecular Diels-Alder cyclization

A stereoselective synthesis of coronafacic acid, a natural component of the phytotoxin coronatin, was achieved using an intramolecular Diels-Alder reaction as the key step. The triene precursor bearing a substituted diene and a vinylketone as dienophile was synthesized and then tested in the thermal intramolecular cyclization. We have devised a new strategy to assemble the E,Z-diene through the stereoselective aldol reaction of an ester enolate followed by a stereoselective dehydration. Following the thermal cyclization, the corresponding hydrindanone thereby obtained with the desired relative stereochemistry could easily be converted into the natural product. The synthesis of the coronafacic acid was accomplished in six steps in 29% overall yield.     

Highly stereoselective synthesis of 1,3-aminoalcohols via Mannich reactions

Diastereoselective synthesis of β-amino ketones by a one-pot Mannich reaction and their subsequent reduction afforded sterically congested enantiomerically pure 1,3-aminoalcohols in high diastereoselectivity: dr up to >98:<2 over two steps. The absolute configurations of the newly created stereogenic centers were assigned by NMR spectroscopy and chemical correlation.     

Highly stereoselective synthesis of 2-deoxy-α- glycosides and α-disaccharides

Highly stereoselective synthesis of 2-deoxy-α-glycosides including disaccharides is described, using S-(2-deoxyglycosyl)phosphorodithioates as glycosyl donors, in the presence of silver perchlorate in acetonitrile     

An approach to the synthesis of furanoheliangolides through Diels-Alder reactions

The core structure of the natural sesquiterpene lactones furanoheliangolides, an 11-oxabicyclo[6.2.1]undecane system, was synthesized through a pathway involving two Diels-Alder reactions.     

Highly diastereoselective synthesis of new indolopyrroloquinolines through intramolecular imino Diels-Alder reactions

A new, efficient and highly diastereoselective one-pot synthesis of cis-fused indolopyrroloquinoline derivatives is described through imino Diels-Alder reaction of substituted anilines or naphthylamines with N-prenylated-2-formyl-3-chloroindoles catalyzed by La(OTf)₃.     

Diels-Alder cycloaddition reactions of 1,3-diazabutadienes with sulfene

Diels-Alder cycloaddition reactions of 1-aryl-4-dimethylamino-2-phenyl(thiomethyl)-1,3-diazabutadienes with sulfene resulting in good yields of 1,2,4-thiadiazine-1,1-dioxide derivatives are reported.     

Regioselective synthesis of novel spiroindane-1,3-diones through 1,3-dipolar cycloaddition reactions

A facile synthesis of novel spiroindane-1,3-diones has been achieved via 1,3-dipolar cycloaddition of an azomethine ylide, generated in situ from ninhydrin and 1,2,3,4-tetrahydroisoquinoline, with the conjugated double bond of chalcone derivatives. The regiochemistry and structures of the cycloadducts were determined with spectroscopic data and by X-ray crystal structure analysis.     

Intramolecular Diels-Alder reactions of 5-vinyl-1,3-cyclohexadienes

[reaction: see text] The intramolecular Diels-Alder reaction of 5-vinyl-1,3-cyclohexadienes affording substituted tricyclo[3.2.1.0(2,7)]oct-3-enes is studied.     

Stereoselective synthesis and Diels-Alder reactions of bis-Ether 1,3 Dienes. A further test for cooperativity during cycloaddition reactions.

A stereoselective synthesis of dienes $\text{1a}$ and $\text{1b}$, using butadiene-iron tricarbonyl complexes, is described. Higher diastereoselectivity is observed during Diels-Alder reaction of $\text{1a}$ as compared with $\text{1c}$, affording good evidence for cooperativity in these cycloadditions.     

Intramolecular Diels-Alder and tandem intramolecular Diels-Alder/1,3-dipolar cycloaddition reactions of 1,3,4-oxadiazoles

The scope of intramolecular Diels-Alder and a novel tandem Diels-Alder/1,3-dipolar cycloaddition cascade of 1,3,4-oxadiazoles is disclosed. In the cases examined, the tandem cycloadditions construct three new rings with formation of four new C-C bonds and set all six stereocenters about a central six-membered ring in a single step including three contiguous and four total quaternary centers without a trace of a second diastereomer.     

Preparation of siloxacyclopentene containing 1,3-dienes and their Diels-Alder reactions

A number of enynyloxy dimethyl and diisopropyl silanes have been prepared and converted into siloxacyclopentene containing 1,3-dienes via intramolecular hydrosilylation of the alkyne functional group. Diels-Alder reactions of these dienes are reported.     

Broadly effective enantioselective Diels-Alder reactions of 1-amino-substituted-1,3-butadienes

[reaction: see text] A broad range of substituted 1-amino-1,3-butadienes undergo enantioselective Diels-Alder reactions with methacrolein in the presence of 5 mol % of Cr(III)-salen complex 1. The reactions are carried out conveniently, at room temperature, and they afford the cycloadducts in high yields and excellent ee's.     

1,3-Dicarbonyl compounds in stereoselective domino and multicomponent reactions

Modern organic synthesis focuses on the discovery and the development of stereoselective multiple bond-forming transformations allowing the creation of several covalent bonds in a single operation. Hence, the number of steps required to obtain a target molecule is reduced, which nicely addresses the efficiency and economy criteria of ‘green chemistry’. In this context, 1,3-dicarbonyl compounds are exceptional synthetic platforms due to the presence of four contiguous reaction sites. This functional group density allows cascades of elemental steps from simple substrates leading to the selective formation of elaborated molecular architectures displaying a large functional diversity.     

Highly stereoselective addition reactions of metallated trans-1,3-dithiane-1,3-dioxide to aldehydes

The sodium anion of trans-1,3-dithiane-1,3-dioxide reacts with unhindered aromatic and heteroaromatic aldehydes to give adducts with 95:5 to 97:3 diastereoselectivity.     

Regio- and stereoselective synthesis of novel tetraspiro-bispyrrolidine and bisoxindolopyrrolidine derivatives through 1,3-dipolar cycloaddition reaction

An efficient approach to the synthesis of a new class of tetraspiro-bispyrrolidines and tetraspiro-bisoxindolopyrrolidines has been accomplished through 1.3-dipolar cycloaddition reaction. The reported method is a one-pot, three component reaction, that is, run under solvent-free microwave conditions.     

Novel synthesis of isoquinolines using isobenzofuran-nitrile Diels-Alder reactions

[reaction: see text] The synthesis of isoquinolines through coupling of 2-alkynylbenzaldehyde derivatives with beta-cyanocarbene complexes has been examined. The reaction involves formation of an isobenzofuran followed by intramolecular Diels-Alder reaction with the nitrile, a process with limited precedent. The unique success of this process in this system has been attributed to deoxygenation of the initial adduct to form the isoquinoline ring system.     

Imino Diels-Alder reactions: One-pot synthesis of tetrahydroquinolines

<正>An efficient synthesis of tetrahydroquinoline derivatives is reported via three component coupling reactions of aldehydes and anilines with various dienophiles in the presence of a catalytic amount of perchloric acid adsorbed on silica gel(HClO_4-SiO_2) under mild reaction conditions.     

Chemo-, regio- and stereoselective Diels-Alder reactions of EWG bearing thiophene-1,1-dioxides

EWG-containing thiophene-1,1-dioxides were found to be very active dienophiles in reactions with 1,3-dienes to afford corresponding cycloadducts in mild conditions. A chemo-, regio- and stereoselective cycloaddition was observed. Reaction resulted in formation of derivatives of tetrahydrobenzothiophene-1,1-dioxides in high yields.