Abstract
The nitration of 11 gave 14-nitro (12) and 13-nitro ester (10), in ca. 1 : 1 ratio. Next, some methyl 7-oxo-derivatives having a substituent in 12 position (18, 19, 21, and 23) were smoothly nitrated to give selectively the corresponding 13-nitro-deisopropyl ester, and the nitration of the corresponding 14-substituted ester (26) gave a mixture consisting of three compounds. On the contrary, a nitration of 39 gave only 14-nitro product (40). Finally, a nitration of 41 gave an addition product (42) to the double bond.
