Influence of the heterocyclic side ring on orientation during nitrations of 1,2‐alkylenedioxy‐annelated benzenes and their mononitro derivatives

Nitration of 1,2‐alkylenedioxybenzenes 1 furnished the respective nitro derivatives 3 and 4 in the relative ratios: 4a:3a/100:trace, 4b:3b/98:2.4, 4c:3c/86:14, 4e:3e/91:9 and 4f:3f/99:1.3. Nitration of 4 gave 5a:6a:8a/0:0:100, 5b:6b:8b/7.7:3.2:89, 5c:6c:8c/23:12:65, 5d:6d:8d/14:74:12, 5e:6e:8e/27:18:55 and 5f:6f:8f/23:7.0:70. Nitration of the isomeric 3 afforded the dinitro products 5, 6 and 7 in the following relative ratios: 5a:6a:7a/92:8:0, 5b:6b:7b/80:20:0, 5c:6c:7c/69:20:1 1, 5d:6d:7d/45:19:36, 5e:6e:7e/37:57:5.9 and 5f:6f:7f/64:36:0. Nitration of 3‐nitro‐1,2‐dimethoxybenzene (9) furnished: 10:11/63:37. Orientation as a function of the heterocyclic ring‐size is discussed.