125874-95-5Relevant articles and documents
Regio-, diastereo-, and chemoselectivities in the dioxirane oxidation of acyclic and cyclic allylic alcohols by methyl(trifluoromethyl)dioxirane (TFD): A comparison with dimethyldioxirane
Adam, Waldemar,Paredes, Rodrigo,Smerz, Alexander K.,Veloza, L. Angela
, p. 349 - 354 (2007/10/03)
The solvent-dependent shift in the regioselectivity of the geraniol epoxidation by methyl(trifluoromethyl)dioxirane (TFD) reveals that as for the less reactive dimethyldioxirane (DMD). hydrogen bonding stabilizes the transition state of the epoxidation. In protic media, the hydrogen bonding is exerted intermolecularly by the solvent, whereas in unpolar, non-hydrogen-bonding solvents intramolecular assistance through the adjacent hydroxy functionality comes into the play and the attack on the allylic alcohol moiety is favored. For chiral allylic alcohols, additional steric interactions control the π-facial selectivity in the conformationally fixed transition state. Analogous to DMD, the preferred dihedral angle in the hydrogen-bonded transition state of the TFD epoxidation constitutes approximately 130°, but contrary to DMD and for synthetic purposes important, the allylic alcohols and derivatives 1 and 3-5 investigated here are chemoselectively epoxidized by TFD without formation of the corresponding enones.
Selective epoxidation of monoterpenes with methyltrioxorhenium and H2O2
Villa De P., Aida L.,De Vos, Dirk E.,Montes De C., Consuelo,Jacobs, Pierre A.
, p. 8521 - 8524 (2007/10/03)
In the presence of pyridine as a co-catalyst, CH3ReO3 catalyses the epoxidation of terpenes such as α-pinene with H2O2 with minimal rearrangement of the epoxide. Pyridine is also critical to suppress isomerisation of the olefin substrate (in case of nerol, geraniol). The reaction can be directed towards selective single or double epoxidation, or in one step towards the rearranged product (e.g. from linalool to the ring- closure product linalool oxide.
The selectivities and the mechanism on highly efficient epoxidation of olefins with 2,6-disubstituted pyridine N-oxides catalyzed by ruthenium porphyrin
Ohtake,Higuchi,Hirobe
, p. 2521 - 2524 (2007/10/02)
Several remarkable selectivities in competitive epoxidations using a ruthenium porphyrin/2,6-disubstituted pyridine N-oxide system were observed. The proposal that the active intermediate of this system differed from the trans-dioxo complex of ruthenium porphyrin was indicatesd.
