The Catalytic Fries Rearrangement and o-Acylation Reactions Using Group 3 and 4 Metal Triflates as Catalysts
Group 3 and 4 metal triflates (Sc(OTf)3, TiCl(OTf)3, Zr(OTf)4, and Hf(OTf)4) were found to be efficient catalysts in the Fries rearrangement of phenyl or 1 -naphthyl acylates. It was also found that the o-acylation (direct acylation) reactions of phenols and 1-naphthols with acid chlorides proceeded smoothly in the presence of the triflates. Both reactions were successfully carried out using small amounts of the triflates (catalytically), and comparison of catalytic activities of these metal triflates in these reactions is discussed.
Kobayashi, Shue,Moriwaki, Mitsuhiro,Hachiya, Iwao
p. 267 - 273
(2007/10/03)
Approach to the Synthesis of Bridgehead Substituted Furo[3,2-b]furans and Side Products of McMurry Reactions
Substituted dihydroxystilbenes 2 are suitable starting materials for the synthesis of photochromic systems derived from 3/4. Attempts to couple the naphthones 8a-8e by the McMurry reaction with TiCl3/LiAlH4 yielded mainly reduction products such as 8f, g or 9. However, the furofuran 3b was isolated when using the zinc-copper couple for reduction. The helicene 11 was formed as an unexpected by-product in the McMurry reaction of the pivaloylnaphthalene 8d.