gem-Dimethyl Effect in a Grignard Reagent Cyclization-Cleavage Rearrengament

Article abstract of DOI:10.1021/jo00319a026

(2,2-Dimethyl-4-penten-1-yl)magnesium bromide (1) is in equilibrium with its cyclic isomer, <(3,3-dimethylcyclobutyl)methyl>magnesium bromide (2).The equilibrium constant for this cyclization has a value of 2E-3.The gem-dimethyl substitution leads to an increase of a factor of about 22 in the equilibrium constant and also retards the rate of cleavage of 2.The sources of the gem-dimethyl effect in this system are discussed.