The asymmetric synthesis of [7]helicene was accomplished in good ee (80%) by kinetic resolution by means of asymmetric olefin metathesis. Three key factors contributed to the success of the kinetic resolution: the use of new Ru-based olefin metathesis catalysts bearing C1-symmetric N-heterocyclic carbene ligands, simple olefins as additives to control the nature of the propagating alkylidene an...

SYNTHESIS 2004, No. 9, pp 1509–1521xx.xx.2004 Advanced online publication: 26.05.2004 DOI: 10.1055/s-2004-822392; Art ID: C0404SS © Georg Thieme Verlag Stuttgart · New York Abstract: The Michael additions of a number of ketones and aldehydes to alkylidene malonates and nitro olefins were studied. The reactions employ small organic molecules as catalyst under mild reaction conditions and do not ...

Differential scanning calorimetry (DSC) analysis of ring opening methatesis polymerization (ROMP) derived polydicyclopentadiene (PDCPD) revealed an unexpected thermal behavior. A recurring exothermic signal can be observed in the DSC analysis after an elapsed time period. This exothermic signal was found to be proportional to the resting period and was accompanied by a constant increase in the ...

The discovery of highly active catalysts and the success of ionic liquid immobilized systems have accelerated attention to a new class of cationic metathesis catalysts. We herein report the facile syntheses of cationic ruthenium catalysts bearing bulky phosphine ligands. Simple ligand exchange using silver(I) salts of non-coordinating or weakly coordinating anions provided either PPh3 or chelat...