A facile and efficient synthesis of (o-hydroxyaryl)glycolic acid derivatives

The Lewis acid-catalyzed addn. reaction of RCOCCO2R1 (R = Me, H, cyclohexyl, Ph, PhCH2, CO2Et; R1 = H, Et) with phenols and 1-naphthols gave glycolic acid derivs. I (R2 = H, Me, Cl; R3 = H, alkyl, OH, OMe, OAc, Br, phthalimido; R4 = H, Me, cyclohexyl, PhCH2, OMe, OPh, SMe, Ph, 2,4-F2C6H3, Cl; and R2R3 = benzo). Thus, a soln. of m-cresol and Et pyruvate in Cl2CH2 was treated with TiCl4 at 0° for 10 min to give 75% I (R = R3 = Me, R1 = Et, R2 = R4 = H)