The present application relates to a process for preparing 5- (a-haloacetyl) -8-substituted oxy- (1 H) -quinolin-2-ones. The process involves, (i) reacting, (a) 8-hydroxy- (1 H) -quinolin-2-one with an acylating agent and a Lewis acid to form 5-acetyl-8-hydroxy- (1 H) -quinolin -2-one； or (b) 8-hydroxy- (1H) -quinolin-2-one with an acylating agent to form 8-acetoxy- (1H) -quinolin-2-one, and treat, in situ, 8-acetoxy- ( 1H) -quinolin-2-one with a Lewis acid to form 5-acetyl-8-hydroxy- (1H) -quinolin-2-one； or (c) 8-acetoxy- (1 H) -quinolin-2-one with Lewis acid to form 5-acetyl-8-hydroxy- (1 H) -quinolin-2-one；(I) a compound in 5-acetyl-8-hydroxy - (1H) - quinoline-2-ona reaction (Pasa (I), the RL formula of which has a base and a solvent to form oz - (1H) - quinoline-2-ona 5-acetyl-8-substitute, R is a protection group and l is a discrete group；y (iii) hacer reaccionar la oxi- (1H) -quinolin-2-ona 5-acetil-8-substituida con un agente de halogenaci n en presencia de un solvente para formar oxi- (1H) -quinolin-2-ona 5 8-acetoxy- (1 H) -quinolin-2-one with a Lewis acid to form 5-acetyl-8-hydroxy- (1 H) -quinolin-2-one； (b) reacting the 5-acetyl-8-hydroxy- (1 H) -quinolin-2-one prepared in Step (a) with a compound having the formula RL in the presence of a base and a solvent to form -acetyl-8-substituted oxy- (1 H) -quinolin-2-one, wherein R is a protective group and L is a leaving group； and (c) reacting the 5-acetyl-8-substituted oxy- (1 H) -quinolin-2-one with a halogenating agent in the presence of a solvent to form a 5- (a-haloacetyl) -8-substituted oxy - (1H) -quinolin-2-one. Claim 14: A process for the preparation of s5 - [(R) - (5,6-2-di-di-ethyl) - 1-hydroxy-ethyl] - 8-hydroxy - (1H) - quinolone-2-ona, including: (a) the reaction of (I) 8-hydroxy - (1H) - quinoline-2-ona with an acidifier and a Lewis acid to form 5-ethyl-8-hydroxy - (1H) - quinoline-2-onaor (ii) 8-hydroxy- (1H) -quinolin-2-one with an acylating agent to form 8-acetoxy- (1H) -quinolin-2-one, an
