REACTIONS OF LITHIO DERIVATIVES OF CARBOXYLIC-ACIDS .2. ALKYLATIONS AND CYCLIZATIONS OF SUBSTITUTED ACRYLIC ACIDS

2-Substituted 3-phenylcinnamic acids are obtained in good yields by effecting bromine-lithium exchange with 2-bromo-3-phenylcinnamic acid and 2 molar equiv of n-butyllithium at -100 °C and subsequent reaction with elec-trophiles (e.g., CH3I, Ph2CO, PhS2Ph). Oxiranes afford γ-butyrolactones in modest yields. In contrast, 2-bromo-acrylic acid polymerizes under such conditions and (Z)-2-bromocinnamic acid dehydrobrominates at -140 °C. Friedel-Crafts cyclization of 2-alkyl-3-phenylcinnamic acids affords 2-alkyl-3-phenylinden-l(lH)-ones in good yields. © 1979, American Chemical Society. All rights reserved.