Intramolecular Nitrone Cycloaddition Reactions Research Articles

ChemInform Abstract: A Tactical Approach for the Synthesis of Novel β‐Lactam‐Substituted, Polycyclic‐Fused Isoxazolidine Derivatives via an Intramolecular [3 + 2] Cycloaddition Reaction.

Abstract The synthesis of functionalized β-lactam-substituted, tricyclic chromenoisoxazolidine and tetracyclic naphthopyranoisoxazolidine derivatives by intramolecular nitrone cycloaddition reaction is described. The O-allyl hydroxyaldehyde derivatives, obtained from Baylis–Hillman adducts (BHA) derived from β-lactam aldehyde underwent intramolecular cycloaddition reaction to give β-lactam-substituted, polycyclic isoxazolidine derivatives in good yield. All the products were confirmed by spectral analysis. The products with a β-lactam substituent may find good applications in biological chemistry.

A tactical approach for the synthesis of novel β-lactam-substituted, polycyclic-fused isoxazolidine derivatives via an intramolecular [3+2] cycloaddition reaction

The synthesis of functionalized β-lactam-substituted, tricyclic chromenoisoxazolidine and tetracyclic naphthopyranoisoxazolidine derivatives by intramolecular nitrone cycloaddition reaction is described. The O-allyl hydroxyaldehyde derivatives, obtained from Baylis–Hillman adducts (BHA) derived from β-lactam aldehyde underwent intramolecular cycloaddition reaction to give β-lactam-substituted, polycyclic isoxazolidine derivatives in good yield. All the products were confirmed by spectral analysis. The products with a β-lactam substituent may find good applications in biological chemistry.

Synthesis of Oxepane Ring Containing Monocyclic, Conformationally Restricted Bicyclic and Spirocyclic Nucleosides from d-Glucose: A Cycloaddition Approach

Carbohydrate-derived substrates having (i) C-5 nitrone and C-3-O-allyl, (ii) C-4 vinyl and a C-3-O-tethered nitrone, and (iii) C-5 nitrone and C-4-allyloxymethyl generated tetracyclic isoxazolidinooxepane/-pyran ring systems upon intramolecular nitrone cycloaddition reactions. Deprotection of the 1,2-acetonides of these derivatives followed by introduction of uracil base via Vorbrüggen reaction condition and cleavage of the isooxazolidine rings as well as of benzyl groups by transfer hydrogenolysis yielded an oxepane ring containing bicyclic and spirocyclic nucleosides. The corresponding oxepane based nucleoside analogues were prepared by cleavage of isoxazolidine and furanose rings, coupling of the generated amino functionalities with 5-amino-4,6-dichloropyrimidine, cyclization to purine rings, and finally aminolysis.

Intramolecular nitrone cycloaddition reaction on carbohydrate-based precursors: application in the synthesis of spironucleosides and spirobisnucleosides.

A simple synthesis of chiral spironucleosides and spirobisnucleosides is described. Intramolecular 1,3-dipolar nitrone cycloaddition reaction of d-glucose-derived precursors having olefin at C-3 and nitrone at C-5, C-1, or C-2 (in nor-series) furnished bisisoxazolidinospirocycles 4-7, 11, and 12 in good yields. Reductive ring opening of the isoxazolidine moieties in 4-6 followed by construction of a nucleoside base upon the generated amino groups smoothly yielded spirobisnucleosides 17 and 18 and spironucleosides 20 and 21.

Synthesis of a difluorinated carbasugar from d-ribose via intramolecular nitrone cycloaddition reaction

Difluorinated carbasugar 3 has been synthesised from d-ribose via an intramolecular nitrone cycloaddition reaction with an overall yield of 22%.

ChemInform Abstract: Application of Intramolecular Nitrone Cycloaddition Reaction: Synthesis of Chiral Aminocarbocycles and Carbocyclic Nucleosides from Carbohydrate Precursors.

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Application of Intramolecular Nitrone Cycloaddition Reaction: Synthesis of Chiral Aminocarbocycles and Carbocyclic Nucleosides from Carbohydrate Precursors

Application of Intramolecular Nitrone Cycloaddition Reaction: Synthesis of Chiral Aminocarbocycles and Carbocyclic Nucleosides from Carbohydrate Precursors