| abstract |
The present invention is directed to an improved process for the preparation of compounds of formula (I) or their salts useful for the treatment of HIV infection. In particular, the present invention provides (2S) -2-tert-butoxy-2- (4- (2,3-dihydropyrano [4,3,2-de] quinolin-7-yl)-useful for the treatment of HIV infection. The subject is an improved process for the preparation of 2-methylquinolin-3-yl) acetic acid or salts thereof. R 4 represents (a), (b), (c), (d), (e), (f), (g), (h), (i), (j), (k), (l) , (M), (n) and (o), wherein R 6 and R 7 are each independently selected from H, halo and (C 1-6 ) alkyl. |