Intramolecular Nitrile Oxide Cycloaddition Reaction Research Articles

Regioselective Preparation of Functionalized Isoxazoline Derivatives as Key Intermediates for the Synthesis of Selective N-Methyl-d-aspartate Receptor Antagonists

Two highly versatile isoxazoline derivatives, as key intermediates for the synthesis of differently functionalized subtype-selective N-methyl-d-aspartate receptor antagonists, were designed and synthesized. The synthetic strategy is based on an intramolecular nitrile oxide cycloaddition reaction which is a powerful method capable of controlling both the regio- and stereochemistry of the pericyclic reaction.

ChemInform Abstract: Stereoselective Synthesis of Azepines Through the Conjugate Addition of Formamides to Nitroalkenes and Subsequent Intramolecular Nitrile Oxide Cycloaddition Reaction.

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Stereoselective synthesis of azepines through the conjugate addition of formamides to nitroalkenes and subsequent intramolecular nitrile oxide cycloaddition reaction

A concise and stereoselective formation of azepines is achieved through the conjugate addition of formamides to nitroalkenes and the subsequent intramolecular nitrile oxide cycloaddition (INOC) reaction. High cis-selectivity was observed. The one-pot modification of the two reactions provides direct preparation of azepines from nitroalkenes and formamides in moderate yields. The formyl group was readily removed by an acidic treatment without significant epimerization.

Stereocontrolled intramolecular nitrile oxide cycloaddition reaction using a gauche–gauche interaction

A gauche–gauche interaction is proposed as a powerful controlling factor for the stereochemistry in the intramolecular nitrile oxide cycloaddition reaction derived from N-protected 3-( N-allylamino)propionaldehyde and 2-( N-homoallylamino)acetaldehyde oximes. High levels of stereoselectivity (76% de to perfect) were obtained from the reaction involving nitrile oxides with substituents at the adjacent carbon atom to the tether nitrogen.

An enantiospecific entry to fluoro substituted aminocyclopentanols through intramolecular nitrile oxide, nitrone, and oxime cycloaddition reactions

Starting from (2 R,3 S)-2-benzyloxy-3-fluoro-5-hexenale 2 and its (2 R,3 R) epimer, cyclopentanoisoxazolidines 4 and 7 are obtained with complete diastereoselectivity through nitrone and oxime intiainolecular cycloaddition reactions. In contrast, cyclopentanoisoxazolines 6 are formed with only medium stereoselectivily through intramolecular nitrile oxide cycloaddition reactions. Further elaboration of these bicyclic compounds affords fluoro substituted aminocyclopetanols 8 and 10 in enantiomerically and diastereoisomerically pure form.

Cycloadditions. 41. Conversion of unsaturated alcohols into functionalized tetrahydrofurans and tetrahydropyrans via nitrile oxide dipolar cycloadditions

The intramolecular nitrile oxide cycloaddition (INOC) of a series of unsaturated oximino ethers has been investigated. The synthesis of the olefinic nitrile oxides involves treating an unsaturated alcohol with a {alpha}-bromoalkanal O-(trimethylsilyl)oxime in the presence of fluoride ion followed by subsequent sodium hypochlorite oxidation. The nitrile oxides were not isolated but spontaneously underwent intramolecular cycloaddition to give fused five- and six-membered ring ethers. The preferred stereoisomer in the formation of the five-membered ring ethers is trans, whereas in the six-membered ring ethers the cis isomer predominates. MM2 calculations help rationalize the observed stereoselectivity. The ratio of diastereomeric products from the INOC reaction appears to correlate with product stabilities. Simple heating of some of the oximino ethers led to intramolecular cycloaddition. The ring closure apparently proceeds subsequent to a tautomeric equilibration of the oxime with a transient nitrone which is trapped by the neighboring {pi}-bond.

ChemInform Abstract: Cycloadditions. Part 38. Formation of Functionalized Cyclic Ethers by Intramolecular Nitrile Oxide Cycloadditions.

AbstractDesilylation of the O‐silyl oximes (I) in the presence of allyl alcohol (II) yields the allyloxy oximes (III) which undergo oxidative cyclization via intramolecular nitrile oxide cycloaddition reaction, forming the fused isoxazolines (IV).

Synthetic studies towards forskolin

A model tricyclic system incorporating the complete array of oxygenated functions of the AB portion of forskolin has been synthetized. The highly substituted decalin unit of the natural target has been in turn assembled in a convenient way utilizing an intramolecular nitrile oxide cycloaddition reaction as key step.

ChemInform Abstract: Stereoselective Intramolecular Nitrile Oxide Cycloaddition to Chiral Allyl Ethers.

Intramolecular nitrile oxide cycloaddition reactions on (Z)- and (E)-chiral allyl ethers occur with poor to good stereoselectivity (diastereoisomeric ratios up to 86: 14), which depends on the double bond configuration as well as on steric and stereoelectronic effects.

Intramolecular nitrile oxide cycloaddition on chiral olefins: a stereocontrolled approach to β-ketol precursors

The intramolecular nitrile oxide cycloaddition reaction on chiral (E) and (Z) olefins featuring a sulphur atom along the carbon chain connecting dipole and dipolarophile occurs with poor to excellent anti stereoselectivity, which is mainly affected by the substitutents at the allylic stereocenter. The possibility of converting the cycloadducts into stereoisomerically pure β-ketols has been established in one case.

Stereoselective intramolecular nitrile oxide cycloaddition to chiral allyl ethers

Intramolecular nitrile oxide cycloaddition reactions on (Z)- and (E)-chiral allyl ethers occur with poor to good stereoselectivity (diastereoisomeric ratios up to 86: 14), which depends on the double bond configuration as well as on steric and stereoelectronic effects.

The intramolecular nitrile oxide cycloaddition route to spirocyclic alkaloids. A total synthesis of isonitramine and sibirine

The Intramolecular nitrile oxide cycloaddition reaction has been found to accommodate the construction of spirocycles in modest yield as revealed by a synthesis of the title alkaloids.

Synthesis of the cis-decahydroquinoline ring system via an INOC reaction of a 1-acyldihydropyridine

Abstract The intramolecular nitrile oxide cycloaddition (INOC) reaction has been utilized in the synthesis of the cis -decahydroquinoline ring system.

The INOC approach to the hydroazulenone ring system - a potential entry tot he guaianolides and pseudoguaianolides.

The intramolecular nitrile oxide cycloaddition reaction has been examined as a method for preparing the hydroazulene ring system.

Diastereoface selection in the inoc reaction

The effect of an “inside” allylic asymmetric center on the course of the intramolecular nitrile oxide cycloaddition reaction has been studied.