A study on selective transformation of norbornadiene into fluorinated cyclopentane-fused isoxazolines

This work presents an examination of the selective functionalization of norbornadiene through nitrile oxide 1,3-dipolar cycloaddition/ring-opening metathesis (ROM)/cross-metathesis (CM) protocols. Functionalization of commercially available norbornadiene provided novel bicyclic scaffolds with multiple stereogenic centers. The synthesis involved selective cycloadditions, with subsequent ROM of the formed cycloalkene-fused isoxazoline scaffolds and selective CM by chemodifferentiation of the olefin bonds of the resulting alkenylated derivatives. Various experimental conditions were applied for the CM transformations with the goal of exploring substrate and steric effects, catalyst influence and chemodifferentiation of the olefin bonds furnishing the corresponding functionalized, fluorine-containing isoxazoline derivatives

Ring-opening metathesis of some strained bicyclic systems; stereocontrolled access to diolefinated saturated heterocycles with multiple stereogenic centers

Ring-opening metathesis (ROM) of various unsaturated, constrained bicyclic ring systems has been investigated with the use of commercial ruthenium-based catalysts. Starting from various cyclodienes, the corresponding derived bicyclic lactone, lactam, and isoxazoline derivatives were submitted to ROM under ethenolysis. These functionalized, strained bicyclic systems afforded novel highly-functionalized diolefinated heterocyclic scaffolds in ROM reactions with stereocontrol, through the conservation of the configuration of the stereogenic centers of the starting compounds

Stereocontrolled synthesis of fluorine-containing functionalized β-lactam derivatives through cross-metathesis reactions

Functionalized β-lactams and their derivatives have generated increasing interest in medicinal chemistry over the last decades. Because of their pharmacological potential the chemistry of fluorinated β-lactams and β-amino acids is considered to be an expanding research field. The stereocontrolled synthesis of various fluorine-containing acylic β-lactams has been accomplished from some readily available unsaturated bicyclic β-lactam isomers. The synthetic strategy was based on ring-opening metathesis of unsaturated bicyclic azetidinones followed by cross-metathesis with fluorine-containing olefins. The cross-metathesis transformations, performed under various conditions with the aim of studying chemodiscrimination of the olefin bonds, resulted in the corresponding functionalized β-lactam derivatives

An Insight into Selective Olefin Bond Functionalization of Cyclodienes through Nitrile Oxide 1,3-Dipolar Cycloadditions

Selective functionalizations of the ring olefin bond of various commercial cyclodienes through nitrile oxide dipolar cycloaddition is described. Nitrile oxides were generated from primary nitroalkanes by Mukaiyama’s method. Besides regioselectivity, the dipolar cycloadditions have been performed in view of selectivity of the ring olefin bonds. The cycloalkenefused isoxazoline products were easily converted through ring opening and cross metathesis into valuable dialkenylated heterocycles

Diversity-Oriented Functionalization of Cyclodienes Through Selective Cycloaddition/Ring-Opening/Cross-Metathesis Protocols; Transformation of a Flatland into Three-Dimensional Scaffolds with Stereo-and Regiocontrol

This article presents selective transformations of some readily available cyclodienes through simple chemical procedures into novel functionalized small-molecular entities. The syntheses hereby described involved selective cycloadditions, followed by ring-opening metathesis of the resulting beta-lactam or isoxazoline derivatives and selective cross-metathesis by differentiation of the olefin bonds on the alkenylated heterocycles. The cross-metathesis transformations have been detailed, which were performed under various experimental conditions with the aim of exploring chemodiscrimination of the olefin bonds and delivering the corresponding functionalized beta-lactam or isoxazoline derivatives