Effects of Reagent Concentrations and Solvents on Reactions of Organomagnesium and Lithium Reagens with o-Quinol Acetates. Differing Reactions Paths from Polymeric Grignards and from Dialkylmagnesiums or Monomeric Grignards

Article abstract of DOI:10.1021/jo00191a015

Studies of the reaction of 6-acetoxy-2,4,6-trimethylcyclohexa-2,4-dien-1-on (2) with isopropylmagnesium bromide showed that decreases in Grignard concentrations resulted in marked reductions in yields of the conjugate addition product, 3-isopropylmesitol (5), and increases in yields of isopropyl mesityl ether (3) and mesitol (4).Similar, though less pronounced, effects were observed with isopropylmagnesium chloride.Reaction of 2 with diisopropylmagnesium or diethylmagnesium resulted in large reductions in yields of 5 or of 3-ethylmesitol.Reactions with dialkylmagnesium reagents or with isopropyllithium were not significantly affected by changes in concentration.It is concluded that electron transfer from diaklylmagnesium reagents are the principal initial steps leading to formation of ethers and reduction products from reactions of o-quinol acetates with Grignard reagents, while non-electron-transfer reactions with the Grignards yield normal and conjugate additions products.