Regio-, Diastereo-, and Chemoselectivities in the Dioxirane Oxidation of Acyclic and Cyclic Allylic Alcohols by Methyl(trifluoromethyl)dioxirane (TFD): A Comparison with Dimethyldioxirane

✍ Scribed by Waldemar Adam; Rodrigo Paredes; Alexander K. Smerz; L. Angela Valoza

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 353 KB
• Volume: 1998
• Category: Article
• ISSN: 1434-193X
• DOI: 10.1002/(sici)1099-0690(199802)1998:2<349::aid-ejoc349>3.0.co;2-r

✦ Synopsis

The solvent-dependent shift in the regioselectivity of the ge-allylic alcohols, additional steric interactions control the πfacial selectivity in the conformationally fixed transition raniol epoxidation by methyl(trifluoromethyl)dioxirane (TFD) reveals that as for the less reactive dimethyldioxirane (DMD), state. Analogous to DMD, the preferred dihedral angle in the hydrogen-bonded transition state of the TFD epoxidation hydrogen bonding stabilizes the transition state of the epoxidation. In protic media, the hydrogen bonding is exerted in-constitutes approximately 130°, but contrary to DMD and for synthetic purposes important, the allylic alcohols and deriva-termolecularly by the solvent, whereas in unpolar, non-hydrogen-bonding solvents intramolecular assistance through tives 1 and 3؊5 investigated here are chemoselectively epoxidized by TFD without formation of the corresponding eno-the adjacent hydroxy functionality comes into the play and the attack on the allylic alcohol moiety is favored. For chiral nes.