1
428
Helvetica Chimica Acta ± Vol. 88 (2005)
This work was supported by the Deutsche Forschungsgemeinschaft. In addition, we are grateful to the
Chemische Werke Hüls AG for a gift of hexamethyl-Dewar-benzene, provided in 1972, and to Prof. Helmut
1
Quast for a gift of 1-azido-2,6-dimethylbenzene ).
Experimental Part
General. The aromatic azides, except 1-azido-2,6-dimethylbenzene, were prepared according to [14]. Flash
chromatography (FC): SiO (0.063 ± 0.032 mm) and Al O (activities I or III). Solvents were of commercial
2 2 3
grade an neither dried nor distilled. M.p.: Kofler hot stage from C. Reichert, Optische Werke AG, Vienna,
À1
Austria. IR Spectra: JASCO FT/IR-410; selected absorption bands in cm . NMR Spectra: Bruker HX 90,
Avance 400, and DMX 600; chemical shifts d in ppm rel. to Me
reference (CDCl : d(H) 7.26, d(C) 77.0; C : d(H) 7.16), coupling constants J in Hz. EI-MS (70 eV): Finnigan
MAT 8200, in m/z (rel. %). Elemental analyses: LECO CHNS-932 elemental analyzer.
,4,5,6,7-Pentamethyl-4-{1-[(2,4,6-trimethylphenyl)imino]ethyl}-4H-1,2-diazepine (4). 1-Azido-2,4,6-trimeth-
ylbenzene (536 mg, 3.32 mmol) and HMDB (518 mg, 3.19mmol) were mixed in a small round-bottomed flask.
The air above the mixture was then replaced by N . The flask was closed, and kept at 50 ± 558 in an oven.
4
Si (0 ppm) by using solvent signals as internal
3
6 6
D
3
2
Although the mixture turned black within several days, an NMR spectrum of a sample indicated that, at best,
very little conversion had occurred. However, after several weeks, the formation of a single product was
discernible in a considerable concentration rel. to that of a number of minor components. After 4 months, the
concentration of the major product did no longer increase. Purification by FC (neutral Al
2 3
O , activity I;
pentane/Et O 1:2) afforded 4 (330 mg, 32%). Colorless solid. M.p. 140 ± 1428. IR (KBr): 2900s, 1650s, 1465s,
2
1
7
435s, 1370s, 1355s, 1295m, 1245m, 1240m, 1220m, 1205m, 1150w, 1085s, 1075m, 9 9 5m , 9 30m, 860m, 850m, 780m,
1
2
10w. H-NMR (600 MHz, CDCl
3
) ): 1.28 (br. s, 3 H) [1.22, 1.51; 108]; 1.77 (s, 3 H) [1.78, 1.73; À 108]; 1.89( s,
ArÀMe) [1.89, 1.82; À 108]; 1.91 (s, 3 H) [1.89, 1.91; À 308]; 1.96 (s, 3 H) [1.93, 1.89; À 108]; 2.00 (s, ArÀMe)
[
2
1
2.01, 2.06; À 108]; 2.178 (s, 3 H) [2.17, 2.14; À 108]; 2.183 (s, 3 H) [2.18, 2.16; À 308]; 2.187 (s, ArÀMe) [2.20,
1
3
2
.23; À 108]; 6.71 (s, 1 H) [6.72, 6.72]; 6.74 (s, 1 H) [6.74, 6.72; À 308]. C-NMR (151 MHz, CDCl
3
) ): 16.4 [16.4,
6.75; À 108]; 16.4 (very br.) [15.9, 19.5; 268]; 16.8 (br.) [16.82, 18.1; 108]; 18.57 (ArÀMe) [18.9, 18.5; 08]; 18.63
(
2
ArÀMe) [18.6, 19.2; 08]; 20.5 (ArÀMe) [20.6, 20.5; À 308]; 21.6 [22.0, 21.8; À 108]; 23.8 (br.) [23.7, 25.8; 158];
4.1 [23.7, 23.9; À 108]; 58.1 [57.4, 58.1; À 58]; 125.1 [125.4, 125.5; À 108]; 125.7 (br.) [125.6, 124.8; 108]; 126.4
[
1
126.3, 126.1; À 108]; 128.3 (CH) [127.9, 128.1; À 108]; 128.6 (CH) [128.2, 128.2]; 131.7 [131.7, 131.9; À 108];
40.3 (very br.) [139.7, 143.0; 208]; 145.4 [144.8, 144.7; À 108]; 153.3 (br.) [154.1, 153.3; À 58]; 155.2 (very br.)
[155.6, 160.2; 268]; 171.4 (very br.) [171.3, 175.0; 268]. EI-MS: 323 (1, M ), 241 (18), 161 (12), 160 (100,
ArNCMe ), 145 (20), 123 (15), 119(18), 91 (17), 41 (10). Anal. calc. for C 21
29 3
H N (323.48): C 77.97, H 9.04, N
1
2.99; found C 78.06, H 8.91, N 12.80.
,4,5,6,7-Pentamethyl-4-{1-[(2,6-dimethylphenyl)imino]ethyl}-4H-1,2-diazepine (5). Prepared from 1-azi-
do-2,6-dimethylbenzene according to the procedure described for 4. Pure 5 was obtained by FC (neutral Al
activity I; pentane/Et O 2 :3) in 33% yield. Colorless solid. M.p. 117 ± 1198. IR (KBr): 3010w, 2981w, 2946m,
3
2
3
O ,
2
2
7
3
914m, 1651vs, 1593m, 1464s, 1437s, 1380m, 1365m, 1357m, 1294w, 1250w, 1201s, 1090s, 1072m, 9 9 6w , 9 30w, 809w,
1
75w, 765m. H-NMR (400 MHz, CDCl
3
, 278): 1.30 (br. s, 3 H); 1.79( s, 3 H); 1.9 2 (s , 3 H); 1.9 4 (s , 3 H); 1.9 7 (s ,
H); 2.04 (s, 3 H); 2.19( s, 3 H); 2.20 (s, 3 H); 6.81 (t, J 7.5, 1 H); 6.90 (d, J 7.5, 1 H); 6.93 (d, J 7.5, 1 H).
1
3
3
C-NMR (101 MHz, CDCl
3
, 278) ): 16.5; 16.6 (very br.); 16.8 (br.); 18.7; 18.8; 21.7; 24.0 (br.); 24.2; 58.1; 122.8
(
CH); 125.5; 125.9; 126.7; 127.7 (CH); 128.0 (CH); 140.3 (very br.); 148.0; 153.3; 155.9 (very br.); 171.3 (very
br.). EI-MS: 309(2, M ), 227 (21), 212 (10), 147 (12), 146 (100, ArNCMe ), 131 (16), 123 (17), 105 (27), 103
11), 79(21), 77 (17). Anal. calc. for C 20 (309.45): C 77.63, H 8.79, N 13.58; found: C 77.35, H 8.85, N 13.53.
(
27 3
H N
1)
2)
See H. Quast, M. Ach, J. Balthasar, T. Hergenröther, D. Regnat, J. Lehmann, K. Banert, Helv. Chim. Acta
005, 88, 1589.
2
NMR Spectra were recorded at 26, À 10, À 30, and À 658. At À 658, two sets of signals were observed,
with an intensity ratio of 6:1, which coalesced at higher temp., and resulted in one set of signals at 268, at
which temp. several signals were still broadened. The date given here are the chemical shifts at 268 and, in
square brackets, the chemical shifts of the major and the minor component at À 658, as well as the
1
13
approximate coalescence temp. As far as specified, assignments are based on NOESY ( H) or HSQC ( C)
spectra.
3)
As far as specified, assignments are based on a DEPT spectrum.