157474-64-1Relevant articles and documents
Asymmetric total synthesis of a beer-aroma constituent based on enantioconvergent biocatalytic hydrolysis of trisubstituted epoxides
Steinreiber,Mayer,Faber
, p. 2035 - 2039 (2001)
A short asymmetric total synthesis of the plant constituent myrcenediol [(R)-1], and (S)-7,7-dimethyl-6,8-dioxabicyclo [3.2.1]octane (2), which is a volatile constituent of the aroma of beer was accomplished via a chemoenzymatic protocol. The key step consisted of a biocatalytic hydrolysis of trisubstituted epoxides bearing olefinic side chains which proceeded in an enantioconvergent fashion, i.e., a single enantiomeric vic-diol was obtained from the racemate in up to 91% ee and 92% isolated yield.
Oxidation of alkenes by oxodiperoxomolybdenum: Trialkyl(aryl)phosphine oxide complexes
Kiraz, Christine I. Altinis,Mora, Luis,Jimenez, Leslie S.
, p. 92 - 96 (2007/12/31)
Catalytic amounts of short-chain (2-4 carbons) trialkylphosphine oxide ligands and MoO5 have been shown to efficiently convert di- and higher substituted alkenes to the corresponding epoxides using a biphasic system with either 30% hydrogen peroxide or 70% TBHP acting as the stoichiometric oxidant. Georg Thieme Verlag Stuttgart.
Olefin epoxidation with hydrogen peroxide catalyzed by lacunary polyoxometalate [γ-SiW10O34(H2O) 2]4-
Kamata, Keigo,Kotani, Miyuki,Yamaguchi, Kazuya,Hikichi, Shiro,Mizuno, Noritaka
, p. 639 - 648 (2007/10/03)
The tetra-n-butylammonium (TBA) salt of the divacant Keggin-type polyoxometalate [TBA]4[γ-SiW10O34-(H 2O)2] (I) catalyzes the oxygen-transfer reactions of olefins, allylic alcohols, and sulfides with 30% aqueous hydrogen peroxide. The negative Hammett ρ+ (-0.99) for the competitive oxidation of p-substituted styrenes and the low value of (nucleophilic oxidation)/(total oxidation), Xso = 0.04, for I-catalyzed oxidation of thianthrene 5-oxide (SSO) reveals that a strongly electrophilic oxidant species is formed on I. The preferential formation of trans-spoxide during epoxidation of 3-methyl-1-cyclohexene demonstrates the steric constraints of the active site of I. The I-catalyzed epoxidation proceeds with an induction period that disappears upon treatment of I with hydrogen peroxide. 29Si and 183W NMR spectroscopy and CSI mass spectrometry show that reaction of I with excess hydrogen peroxide leads to fast formation of a diperoxo species, [TBA]4[γ-SiW10O32(O2) 2] (II), with retention of a γ-Keggin type structure. Whereas the isolated compound II is inactive for stoichiometric epoxidation of cyclooctene, epoxidation with II does proceed in the presence of hydrogen peroxide. The reaction of II with hydrogen peroxide would form a reactive species (III), and this step corresponds to the induction period observed in the catalytic epoxidation. The steric and electronic characters of III are the same as those for the catalytic epoxidation by I. Kinetic, spectroscopic, and mechanistic investigations show that the present epoxidation proceeds via III.
