Use of a tandem ring-opening-ring-closing metathesis (RORCM) strategy for the synthesis of functional metathesis catalysts is reported. Ring opening of 7-substituted norbornenes and subsequent ring-closing metathesis forming a thermodynamically stable 6-membered ring lead to a very efficient synthesis of new catalysts from commercially available Grubbs' catalysts. Hydroxy functionalized Grubbs'...

An arene-terminated epoxy olefin cyclization was promoted by a water-tolerant Lewis acid to give tri- and tetracyclic 3beta-hydroxy terpenoids and steroid derivatives in 57 and 37% yields, respectively, per new formed ring up to 75%.

AIM The objective of this laboratory investigation was to determine the effect of different preparation designs (light chamfer, deep chamfer, and shoulder) and die-making materials (stone and epoxy) on the resulting margin misfit for fiber-reinforced composite crowns using a measuring microscope. METHODS AND MATERIALS Sixty standardized FibreKor crowns were made on stone and epoxy resin dies ...

Abstract Bicyclic alkenes, including oxa- and azabicyclic readily undergo activation with facial selectivity in the presence of transition-metal complexes. This is due to intrinsic angle strain on carbon–carbon double bonds such unsymmetrical bicyclic systems. During past decades considerable progress has been made area ring opening strained rings by employing concept C–H activation. short revi...

CVT + SCT calculations on the rate of tunnelling at 20 K in the ring opening of cyclopropylcarbinyl radical, substituted with geminal methyl groups at a ring carbon (1b), have been performed. The calculations predict that, contrary to expectations based on the effect of mass on the rate of tunnelling, the geminal methyl substituents in 1b should make the rate of ring opening to 1,1-dimethyl-3-b...

Nucleophilic ring opening of dl and meso 1,1¢- dicyclohexenyl diepoxides by sodium azide in dioxane and aqueous alcoholic medium give the corresponding azidoalcohols. The obtention of departure diepoxides from diazidoalcohols by the reaction with sodium hydride shows the anti position of OH and N3 groups.

For the first time B-podands have been studied as an efficient and powerful catalysts in the ring opening of epoxides with azide anion in water. The reaction afforded the corresponding 1,2-azidoalcohols with high regioselectivity under mild reaction conditions and in a highly atom economic fashion.

Quantum yields for photochemical ring opening of six alkylcyclobutenes have been measured in hexane solution using 228-nm excitation, which selectively populates the lowest pi,R(3s) excited singlet states of these molecules and has been shown previously to lead to ring opening with clean conrotatory stereochemistry. The compounds studied in this work-1,2-dimethylcyclobutene (1), cis- and trans-...

Linear hybrid block copolymers with well controlled molecular weights and narrow polydispersities were synthesized via ring-opening metathesis polymerization (ROMP) followed by ring-opening polymerization of amino acid N-carboxyanhydrides.

A new method for asymmetric ring opening of terminal aziridines using a chiral amine, (DHQD)(2)AQN, is described; the reaction is based on the asymmetric recognition of aziridines using (DHQD)(2)AQN and on sequential ring opening using TMSNu.