135225-27-3Relevant academic research and scientific papers
Lewis acidic catalysts for olefin epoxidation by iodosylbenzene
Yang, Yihui,Diederich, Fran?ois,Valentine, Joan Selverstone
, p. 7195 - 7205 (1991)
A ferric complex, (Et3HN) FeIII(bpb)Cl2, has been synthesized, and its structure has been determined by X-ray crystallography. This complex and its inflate derivative, (Et3HN)FeIII(bpb)(OTf)2, are found to catalyze the epoxidation of a variety of olefins by iodosylbenzene, OIPh. These reactions give little allylic oxidation of cyclohexene and stereochemical retention with cis-stilbene. Al(OTf)3, a nonredox metal salt, has also been found to catalyze the epoxidation of cyclohexene by iodosylbenzene, and the reactivity is quite similar to that of Fe(OTf)3, which, we studied previously. In addition to epoxides, other products were observed. For the reactions containing Fe(OTf)3, Al(OTf)3, or (Et3HN) FeIII(bpb)(OTf)2, cis-1,2-cyclohexanediol ditrifilate and 3-acetamidocyclohexene were found. The amide oxygen in 3-acetamidocyclohexene was derived from iodosylbenzene as verified by isotopic labeling using 18OIPh. For the reactions containing (Et3HN) FeIII(bpb)Cl2 FeCl3, or AlCl3, trans-1,2-dichlorocyclohexane and 3-chlorocyclohexene were observed. 1,4-Diiodobenzene was found in all of the reactions. The presence of these products suggests strongly that the mechanisms of these reactions are related to those occurring between soluble iodine(III)-containing compounds and olefins in the absence of any metal catalysts. A new mechanisms that accounts for all of the products is proposed which involves electrophilic attack on the olefin by the iodine(III) center in a metal-iodosylbenzene complex. The reactions of PhI(OAc)2 with norbornenecarboxylic acid or nortornene in different solvents were also investigated. The products isolated were shown to be 5-(acetyloxy)-3,3a,4,5,6,6a-hexahydro-[3β,3aα,5α,6β, 6aα]-3,6-methano-2H-cyclopenta [b] furan-2-one (1), 5-acetamido-3,3a,4,5,6,6a-hexahydro-[3β,3aα,5α,6β, 6aα]-3,6-methano-2H-cyclopenta [b] furan-2-one (2), and exo-2-acetoxy-syn-7-acetamidonorbornane (3). The structures of 1 and 3 were determined by X-ray crystallography. The formation of these products provides additional evidence for the electrophilic character of iodine(III) compounds.
