218 Synthetic Routes toN-Nitro
anhydride–nitric acid mixtures.^107 In these reactions, ring nitration to 2,4-dinitro-N, N-
dimethylaniline is followed by cleavage of one of the N–CH 3 bonds to form the nitramino
functionality; subsequent ring nitration yields tetryl (Section 5.14).
5.6.2.2 Tert-Butyl groups
The nitrolysis of tertiary amines containing atert-butyl group is synthetically useful and often
gives a high yield of the corresponding secondary nitramine. Thetert-butyl group can be
used as a blocking group for the Mannich condensation of polynitroalkanes with amines and
formaldehyde. The need for a blocking group is essential to avoid multiple condensations which
can lead to a complex mixture of products or even polymerization. Mannich condensations
employingtert-butylamine have provided many polynitro derivatives of aliphatic amines in
which atert-butyl group blocks the amine functionality.
NNNO 2 N NO 2
O 2 N NO 2t-BuO 2 N NO 2t-Bu t-BuNO 2 NNO 2t-But-BuNN NO
2O 2 Nt-But-BuN(CH 3 )2. HCl (99) (CH 3 ) 2 NNO 2 (100)H 2 SO 4 , HNO 3H 2 SO 4 , HNO 3100 % HNO 381961a1b87Ac 2 O, HNO 354432(95)(97)
NN NO
2NO 2O 2 NO 2 N(98)(93)
NNNO 2NO 2O 2 NO 2 N(94)100 % HNO 3 595 Ac 2 O, HNO 3 55Table 5.5
Synthesis of secondary nitramines from the nitrolysis of tert-butylamines
(ref. 108)Entry Substrate Nitrolysis agent Product Yield (%)(91)NO 2 N NO 2
NO 2NO 2O 2 N(92)O NO 2 NNO 2O 2 N(96)
OAdolph and Cichra^108 prepared a number of cyclic nitramines from the nitrolysis oftert-
butyl protected Mannich products (Table 5.5). Nitrolysis of thetert-butyl groups was achieved
with mixed acid, pure nitric acid or a mixture of nitric acid in acetic anhydride depending on the
substrate. Pure nitric acid was found to affect the nitrolysis of both thetert-butyl groups of (97),
(Table 5.5, Entry 4) whereas the use of mixed acid led to the isolation of the product where only
one of thetert-butyl groups had undergone nitrolysis. Some of the cyclic nitramine products