The N-Lithiation of 2,4,6-Triphenylborazine
FULL PAPER
st, 999 m, 912 m, 900 m, 854 m, 845 m, 756 wt, 721 st, 716 st, 704
vst, 621 m, 617 m, 486 m cm . C31H B LiN O (509.05): calcd.
39 3 3
C 73.15, H 7.72, N 8.25; found C 71.88, H 7.73, N 8.16.
1
1
PhB(Cl)NHSiMee
for 1 was observed (δ B = 34.8 ppm). All volatiles (CH
SiCl) were then removed in vacuo and the residue crystallized from
3
(δ B = 37.6 ppm) vanished and only the signal
11
–1
2
Cl
2
, Me
3
-
1
3
diethyl ether. Yield: 45.4 g, 98%. M.p. 180–185 °C. C NMR
): δ = 128.4, 130.1, 132.4 ppm. 1 B NMR: δ = 34.8 ppm.
1
Bis(diethyl ether)lithium 2,4,6,6-Tetraphenylborazinate–lithium–
,4,6-triphenylborazine (7): To a stirred solution of 1 (0.858 g,
6 6
(C D
2
(Tetramethylethylenediamine)lithium–2,4,6-triphenylborazine–(tetra-
2.7 mmol) in diethyl ether (50 mL) was slowly added a 2 solution
methylethylenediamine)lithium Iodide (2): 1 (1.03 g, 3.34 mmol) was of LiPh (1.39 mL, 2.78 mmol) in diethyl ether/cyclohexane. The
dissolved in diethyl ether (60 mL) at 0 °C. With stirring, a solution
of commercial LiMe (containing LiI) in diethyl ether (2.20 mL,
brownish solution was then stirred for 5 d at ambient temperature
followed by reduction of its volume to 20 mL in vacuo. The solu-
tion was kept at –5 °C. Colorless crystals separated from the
slightly brown solution. Yield: 1.05 g of 7, 91%. M.p. 130–132 °C
3.52 mmol) and TMEDA (1.0 mL) was added drop wise to the bor-
azine solution. After warming to ambient temperature, the clear
solution was stirred for 2 d and then reduced in volume to about
1
3
(dec.). H NMR (C
6
D
6
): δ = 1.07 (t, 12 H, CH
2
CH
3
, JH,H = 7 Hz),
3
2
0 mL. At –5 °C colorless prisms separated from the slightly brown
3.20 (q, 8 H, OCH
(br. s, 2 H, N-3,5-H) 6.94–7.58 (m, 35 H, PhB) ppm. C NMR: δ
2
, JH,H = 7 Hz), 4.64 (br. s, 2 H, N-1Ј,5Ј-H), 5.57
1
13
solution. Yield: 2.10 g, 92%. M.p. 173–175 °C. H NMR (C
2.00 (s, 24 H, NCH ), 2.14 (s, 8 H, NCH
) ppm. 13C NMR: δ = = 15.2 (CH
6.0, 58.2 ppm. B NMR: δ = 34.1 (h1/2 = 350 Hz) ppm. 170 Hz), 33.5 (h1/2 = 360 Hz) ppm. Li NMR: δ = 0.9 (h1/2
IN Li (680.98): calcd. C 52.91, H 7.25, I 18.63, N 14.40;
found C 52.86, H 7.13, I 18.51, N 14.22.
6 6
D ): δ
11
=
4
C
3
2
2
CH
3
), 65.8 (OCH
2
) ppm. B NMR: δ = –4.6 (h1/2
=
=
11
7
30
H
49
B
3
7
2
80 Hz), 2.4 (h1/2 = 120 Hz) ppm. IR (Nujol, Hostaflon; only me-
dium to very strong bands quoted): ν˜ = 3446 m, 3430 m, 3074 m,
3
049 st, 3009 st, 2997 st, 2977 st, 2931 st, 2898 m, 2862 m, 1599
vst, 1571 m, 1501 vst, 1479 st, 1424 vst, 1399 vst, 1359 m, 1339 m,
312 st, 1300 m, 1264 m, 874 m, 752 st, 743 m, 705 vst, 663 m, 652
(
1,3,5-Trimethylhexahydrotriazine)lithium 2,4,4,6-Tetraphenylboraz-
inate (3): 1 (1.17 g, 3.79 mmol) was placed into a flask containing
diethyl ether (60 mL). The suspension was cooled to 0 °C. To a
solution of LiMe (prepared from Li grains and MeCl in diethyl
ether, 4.0 mmol, 2 5 mL, 1.6 ) diluted with diethyl ether (10 mL)
was added trimethylhexahydrotriazine (1.1 mL, 7.8 mmol). This
LiMe reagent was slowly added dropwise into the diethyl ether
solution of 1 at 0 °C. A clear solution resulted which was stirred
for 2 d and then reduced in volume in vacuo. On keeping the solu-
1
–1
60 6 2 6 2
m, 682 m, 515 m cm . C50H B Li N O (855.82): calcd. C 70.17,
H 7.07, N 9.82; found C 70.95, H 7.89, N 9.43.
Bis(diethyl ether)lithium N-Lithio-tetraphenylborazinate (6a): To a
stirred solution of 1 (0.640 g, 2.07 mmol) in diethyl ether (60 mL)
a solution of LiPh in diethyl ether/cyclohexane (2 , 2.15 mL,
4.3 mmol) was added dropwise at 0 °C. The mixture was stirred 4 d
at ambient temperature. Then its volume was reduced to about
20 mL in vacuo. The brown solution was stored at –5 °C. After a
few days, colorless crystals were isolated. Yield: 0.962 g of 6a, 85%.
The same compound was also obtained by treating 1 with 3 or 4
tion at –5 °C, colorless prisms of 3 separated (1.90 g, 3.63 mmol,
1
9
3
5%). M.p. 91–95 °C. H NMR (C
6
D
6
): δ = 1.95 (s, 9 H, NCH
3
),
.01 (s, 6 H, NCH
2
) ppm. 13C NMR: δ = 38.4, 76.6 ppm (azin).
B NMR: δ = –5.2 (h1/2 = 150 Hz), 33.1 (h1/2 = 400 Hz) ppm (ratio
1
1
7
11
1
:2). Li NMR: δ = 2.1 (h1/2 = 40 Hz) ppm. IR (Nujol/Hostaflon;
equiv. of LiPh (only tested by B NMR). When compound 6a was
only medium to strong signals): ν˜ = 3411 m, 3077 m, 3053 m, 3030
m, 3013 m, 2992 m, 2050 m, 2870 m, 2795 m, 2734 m, 2720 m,
kept in vacuo, 1.5 equiv. of diethyl ether was lost. M.p. 140–142 °C.
1
3
3
H NMR: δ = 1.07 (t, CH
2
CH
3
, JH,H = 7 Hz), 3.20 (q, JH,H =
2711 m, 1600 m, 1502 st, 1474 st, 1441 vst, 1422 vst, 1408 vst, 1347
7 Hz, 8 H, OCH
2
), 5.78 (br. s, 4 H, HN-1,1Ј,5,5Ј) ppm. 13C NMR:
1
1
m, 1314 m, 1272 st, 1502 st, 1474 st, 1441 vst, 1408 vst, 1347 m, δ = 15.3 (CH
2
CH
3
), 65.7 (OCH
2
) ppm. B NMR: δ = –5.9 (h1/2
=
=
7
1314 m, 1272 st, 1195 m, 1157 m, 1118 vst, 1029 m, 1016 st, 939 130 Hz), 36.8 (h1/2 = 800 Hz) ppm. Li NMR: δ = –0.39 (h1/2
st, 930 m, 866 m, 762 m, 756 m, 732 st, 704 vst, 671 st, 6521 m,
150 Hz), 3.0 (h1/2 = 150 Hz) ppm. IR (Nujol, Hostaflon; only me-
dium to very strong bands quoted): ν˜ = 3096 m, 3047 m, 2926 m,
1596 m, 1499 m. 1483 m, 1434 st, 1343 vst, br, 1278 st, 1245 m,
–1
581 m, 557 m cm . C30
38 3 6
H B LiN (522.06): calcd. C 69.02, H 7.34,
N 16.10; found C 68.08, H 7.42, N 15.71.
1
188 m, 1070 m, 1027 m, 851 st, 805 m, 755 m, 737 st, 703 vst, 683
(
(
(
(
Diethyl ether)lithium 1,3,5-Trimethyl-2,4,6,6-tetraphenylborazinate
–1
54 6 4 6
st, 585 m, 491 m cm . C52H B Li N O (891.67) [dimeric mono(di-
ethyl ether) adduct]: calcd. C 71.65, H 6.24, N 9.64; found C 71.39,
H 6.27, N 9.03.
5): To a stirred solution of (PhBNMe)
3
, 4,[ in diethyl ether
13]
0.304 g, 0.86 mmol, 40 mL) was added at 0 °C a solution of LiPh
0.45 mL, 0.9 mmol) in diethyl ether/cyclohexane (1:1). The re-
sulting clear yellow solution was stirred for 2 d at ambient tempera-
ture and then reduced to a volume of ca. 20 mL in vacuo. On stor-
ing the solution at –5 °C crystals separated within a few days. Yield:
Tris(tetrahydrofuran)lithium N-Lithio-2,2,4,6-tetraphenylborazinate
(6c): N,NЈ,NЈЈ-trimethylhexahydrotriazine (1.83 g, 14.2 mol) was
added to a hexane solution of nBuLi (5.0 mL. 1.6 , 8.0 mmol).
This slightly yellow solution was then added to a stirred solution
1
0
6
2
(
7
.42 g of 5, 95%. M.p. 165 °C (dec.). H NMR (C
6
D
6
): δ = 0.68 (t,
H, CH
.90 (q, 4 H, OCH
2
CH
3
), 2.49 (s, 6 H, 1,5-NCH
), 7.13 (t, 4 H, m-PhB-2,6, JH,H = 7.0 Hz), 7.17 noted after a few drops had been added. After addition, the mix-
t, 2 H, m-PhB-4, JH,H = 7.0 Hz), 7.19 (t, 2 H, m-PhB, JH,H
.0 Hz), 7.25 (t, 1 H, p-PhB-4, JH,H = 7.0 Hz), 7.26 (t, 1 H, p- was isolated by filtration and was then dissolved in THF (25 mL).
PhB-4Ј, JH,H = 7.0 Hz), 7.30 (t, 2 H, m-PhB-2,6, JH,H = 7.0 Hz),
3
), 2.71 (s, 3 H, 3-NCH ), of 1 (2.34 g, 7.76 mmol) in hexane (40 mL). Gas evolution was
3
3
2
3
3
=
ture was kept at reflux for 14 h. The solid (1.65 g, most likely 6b)
3
3
3
After removal of the solvent, a brown oil remained. Most of the
oil solidified on storing for several days. The resulting colorless
crystals were isolated and washed with a small amount of pentane.
Yield: 1.62 g of 6c, 56%. M.p. 148–151 °C. Several of the crystals
had single-crystal quality. By dissolving 6a in THF the same com-
4
7
4
.35 (dd, 4 H, o-PhB-2,6, 3
J
H,H = 7.0,
JH,H = 1.0 Hz), 7.59 (d,
): δ = 14.9
3
13
H, o-PhB-2,2Ј, JH,H 7.0 Hz) ppm. C NMR (C
6
D
6
1
1
(CH
2
CH
3
), 36.6 (NCH
3
), 37.2 (NCH
3
), 64.6 (OCH
2
) ppm.
B
7
NMR: δ = 1.9 (h1/2 = 130 Hz), 37.2 (h1/2 = 400 Hz) ppm. Li NMR:
δ = 2.1 (h1/2 = 40 Hz) ppm. IR (Nujol/Hostaflon; only medium to
very strong signals): ν˜ = 3067 st, 3044 st, 3006 st, 2997 st, 2982 st,
1
pound separated from a concentrated solution kept at –25 °C. H
3
3
NMR: δ = 1.37 (t, JH,H = 7 Hz, 24 H, OCH
), 5.78 (br. s, 4 H, N-1,1Ј,5,5Ј) ppm. C NMR:
), 68.3 (OCH
) ppm. 11B NMR: δ = –3.5, 34.2
258 st, 1194 m, 1160 m, 1146 st, 1111 m, 1064 st, 1044 m, 1019 ppm. Li NMR: δ = –0.39 (h1/2 = 40 Hz), 1.58 (h1/2 = 10 Hz) ppm.
2
CH), 3.54 (q, JH,H
1
3
2
945 st, 2894 st, 2852 m, 2819 m, 1595 st, 1567 m, 1497 st, 1481 = 7 Hz, 24 H, OCH
2
st, 1466 st, 1431 st, 1397 vst, 1368 st, 1355 vst, 1298 vst, 1265 st, δ = 26.2 (OCH CH
2
2
2
7
1
Eur. J. Inorg. Chem. 2005, 3524–3535
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3533