The pseudo-enzymatic action of tri-o-thymotide clathrates applied to the determination of the absolute configuration of four halohydrins
作者:Raymond Gerdil、Giacomo Barchietto
DOI:10.1016/s0040-4039(00)70648-4
日期:——
The heterogeneous reactions of gaseous HCl and HBr, as external agents, with trans-2,3-dimethyloxirane and 2,2,3-trimethyloxirane as guestmolecules in tri-o-thymotideclathrates are shown to allow the ready determination of the absolute configuration of the end-products owing to highly specific host-reactant interactions.
Demonstration of a Phosphazirconocene as a Catalyst for the Ring Opening of Epoxides with TMSCl
作者:Li-Sheng Wang、T. Keith Hollis
DOI:10.1021/ol034816r
日期:2003.7.1
[GRAPHIC]In this study, it was demonstrated for the first time that a phosphazirconocene catalyzes the ring opening of epoxides with TMSCI. This reactivity leads to a facile preparation of chlorohydrins. The late transition metal Fe analogue was found to catalyze the reaction at rates and stereoselectivity comparable to those of the Zr complex.
Synthesis of Oxochromium(VI) Alkoxides via Epoxide Cleavage. Structure, Reactivity, and Mechanism
作者:Christian Limberg、Tobias Wistuba
DOI:10.1021/jo982357f
日期:1999.8.1
In an NMR spectroscopic study the cleavage of epoxides [ethylene, propylene, and cis/trans-butylene oxide] by chromyl chloride giving access to oxochromium(VI) alkoxides was shown to proceed via a bimolecular rate-determining step where two molecules of a complex CrO2Cl2... epoxide collide. Subsequently one Cl ligand at the first Cr center attacks the backside of an epoxide molecule complexed at the Cr center of a second CrO2Cl2... epoxide molecule and vice versa. The traits-opening of the epoxides was proved by determining the configuration of the chlorohydrins resulting from hydrolysis of the corresponding alkoxide products in the cases of cis- and trans-butylene oxide. The NMR data provide evidence that each oxochromium(VI) alkoxide adopts one preferred conformation in solution although DFT calculations did not indicate any special stabilizing effects. The product formation was rationalized by DFT calculations concerning the thermodynamics of the reactions.