7436-01-3Relevant articles and documents
Asymmetric Ring-Closing Metathesis Catalyzed by Chiral Molybdenum Alkylidene Complexes
Fujimura, Osamu,Grubbs, Robert H.
, p. 824 - 832 (2007/10/03)
Kinetic resolution was observed in ring-closing metathesis of racemic dienes catalyzed by the newly developed chiral molybdenum alkylidene complexes (R,R)-Mo(CHCMe2Ph)(NAr)(TBEC) 1 (Ar = 2,6-i-Pr2C6H3, TBEC = 2′,2′ ,2″,2″-tetrakis(trifluoromethyl)-1,2-bis(2′-hydroxyethyl) cyclopentane) and (R,R)-Mo(CHCMe2Ph)(NAr)(TBEH) 2 (Ar - 2,6-i-Pr2C6H3, TBEH = 2′,2′,2″,2″-tetrakis(trifluoro- methyl)-1,2-bis(2′-hydroxyethyl)cyclohexane). In the case of a prochiral symmetric triene substrate, optically active cyclized product was formed by catalytic ring-closing metathesis with 1, which opens the possibility of a new version of two-directional synthesis. Although the observed enantiomeric excesses were modest to low, this data demonstrates the feasibility of asymmetric induction by chiral alkylidene catalysts in ring-closing metathesis.
Deazetation of a Bicyclic Azo Compound: Resolution of a Stereochemical Ambiguity and Conformational Analysis of a Biradical
Samuel, Christopher J.
, p. 1259 - 1265 (2007/10/02)
Development of a new approach has permitted a fuller analysis of the stereochemistry of deazetation of the stereospecifically deuteriated azo compound (1d) than could be achieved previously, in that it has proved possible to analyse 2H2>octa-1,7-diene for E,E-, E,Z,-and Z,Z-content.This has given results for the thermal and photochemical reactions that can be rationalised in terms of partial conformational equilibration of the biradical.
Conformational Equilibrium in 8-Methyl-cis-2-thiahydrindane and 8-Methyl-cis-2-oxahydrindane by 13C NMR Spectroscopy
Willer, Rodney L.
, p. 261 - 265 (2007/10/02)
The preferred conformation of 8-methyl-cis-thiahydrindane has been both estimated by 13C NMR chemical shifts and determined by low temperature 13C NMR spectroscopy to be the conformer with the methyl group equatorial with respect to the cyclohexane ring.This result is in disagreement with the interpretation of the temperature dependence of the CD spectra of (+) and (-) 8-methyl-cis-2-thiahydrindane, whereby the conformation with the methyl group axial with respect to the cyclohexane ring was claimed to be the preferred conformation.The preferred conformation of the related oxygen heterocycle, 8-methyl-cis-2-oxahydrindane, has been estimated by 13C NMR chemical shifts to be the conformer with the methyl group axial with respect to the cyclohexane ring.Possible reasons for these observations are discussed.
Struktur eines O,N-Ketenacetals: (1RS,8SR,10SR)4(15)Z)-4-Aethyliden-5-oxa-3-azatricyclo3,8>tetradecan)
Kuemin, Albin,Maverick, Emily,Seiler, Paul,Vanier, Noel,Damm, Lorenz,et al.
, p. 1158 - 1175 (2007/10/02)
Methods for the preparation of a series of model compounds which were required for stereochemical studies are described: the tricyclic O,N-ketenacetal 1, the two diastereomeric bicyclic amino acids 7 and 10 (see Scheme 2), and the two diastereomeric conformationally fixed tetrahydro-1,3-oxazines (=1,3-oxazines) 9 and 11.An x-ray analysis of racemic 1 reveals a quasi-tetrahedral nitrogen pyramid of the O,N-ketene acetal grouping, and an almost perfect conformational analogy between the N- and C-centered allylic positions at the double bond.
