Vanadyl butylate

The vanadium(IV) complex of salen in zeolite was found to be an effective catalyst for the room temperature epoxidation of cyclohexene using t-butyl hydroperoxide as oxidant.88 Well-characterized vanadyl bis-bipyridine complexes encapsulated in Y zeolite were used as oxidation catalysts.101 Ligation of manganese ions in zeolites with 1,4,7-triazacyclononanes gives rise to a binu-clear complex stabilized by the zeolites but allows oxidation with excellent selectivity (Scheme 7.4). 

Vinylallenes can also be cydized oxidatively. Vinylallene 61 when treated with vanadyl acetonacetonate and tert-butyl hydroperoxide in benzene produced cyclopen-tenone 63, the immediate precursor of methylenomytin B (cf. 5, Eq. 13.1), in 50%... 

I.POXIDATION, ASYMMETRIC (--)-Benzylquininium chloride. f-Butyl hydroperoxide-Vanadyl acetoacetate. Hydrogen peroxide-1,1,3,3-Tetrachloro-aceione. (SM2-Hydroxy-N,N-diinethyl-propanamidc-OtO )oxodiperoxymolyb-denum(VI). 

Bis(acctonitro)chloronitropalladium(II). /-Butyl hydroperoxide-Dialkyl taitratesr-Vanadium(IV) isoproxide. t-Butylhydroperoxide-Molybdenum carbonyl. t-Butylhydroperoxide-Vanadyl acetylacetonate. [(— )-Camphor-10-ylsulfonyl]-3-aryloxaziridines. m-Chloroperbenzoic acid-Potassium fluoride. Dimethylsulfonium methylidc. 3,5-Dinitroperbenzoic acid. Hydrogen peroxide-Vilsmeier reagent. p3-Oxohexakis(p-... 

Butyl hydroperoxide-Vanadyl acetylacetonate-Titanium (IV) isopropoxide. 

The readily available catalyst vanadyl bisacetylacetonate when used with r-butyl hydroperoxide in benzene will oxidize secondary alcohols (Scheme 20) much more rapidly than primary ones (rate ratio > 100 1), but the other oxidizing properties of this system, in particular the epoxidation of allylic alcohols and the cleavage of 1,2-diols might well limit its uses somewhat. ... 

Very interesting results were obtained during studies on the epoxidation of /f-hydroxy enones 8. Attempts at selective epoxidation under typical basic conditions failed and 2 3 mixtures of syn- and anf/-epoxides 9 were obtained. Surprisingly, epoxidation using Sharpless conditions, titanium tetraisopropoxide/tm-butyl hydroperoxide or vanadyl acetylacetonate/rm-butyl hydroperoxide, which are normally unreactive towards simple enones, proceeded smoothly, yielding exclusively syn-epoxy alcohols syn-9. No epoxidation took place for the corresponding nitrile or when the hydroxy function was blocked as a silyl ether32. 

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