1-Methyl-1-azacyclohexa-2,3-diene(NϪB)borane
FULL PAPER
diethyl ether (3 ϫ 40 mL), the combined organic layers were dried
with MgSO and concentrated in vacuo. The residue was purified
by flash chromatography [SiO , light petroleum ether (b.p. 30Ϫ50 H, 8-H), 5.13 (br. s, 1 H, 5-H), 5.61 (br. q, average of J3n,4, J3x,4
C)/diethyl ether, 2:1] to give, in order of elution, 8b (16 mg, 3%) and J4,8a ϭ 2.8 Hz, 1 H, 4-H), 6.32 (dd, J6,7 ϭ 5.6, J ϭ 1.8 Hz, 1
as a yellowish oil and 8a (60 mg, 10%) as yellowish crystals with H) and 6.39 (dd, J6,7 ϭ 5.6, J ϭ 1.3 Hz, 1 H) (6-H, 7-H); the signals
H
x
), 2.78 (s, 3 H, CH
3
), 3.48 (br. quint, average of J3n,8a, J3x,8a,
4
J4,8a and J8,8a ϭ 2.8 Hz, 1 H, 8a-H), 5.08 (br. d, J8,8a ϭ 3.6 Hz, 1
2
°
m.p. 95Ϫ98 °C. In one experiment, 8a was contaminated with ca.
of 2-H
n
1
, 3-H
x
, and the BH
3
group are superimposed by signals of
): δ ϭ 24.0 (C-3), 55.0 (CH ),
3
3% of 8c.
8a. Ϫ C NMR (63 MHz, CDCl
3
3
6
1.3 (C-2), 68.3 (C-8a), 78.6 and 80.9 (C-5, C-8), 114.5 (C-4), 131.2
8
9
J
a: 1H NMR (600 MHz, CDCl
3
): δ ϭ 1.72 (very br. q, JB,H
), 2.08 (dddt, J3,3 ϭ 18.6,
2x,3n ϭ 12.0, J2n,3n ϭ 6.8, average of J3n,4 and J3n,8a ϭ 3.0 Hz, 1
), 2.21 (ddt, J3,3 ϭ 18.6, J2x,3x ϭ 6.1, average of J3x,4 and
3x,8a ϭ 2.9 Hz, 1 H, 3-H ), 2.95 (dd, J2,2 ϭ 13.8, J2n,3n ϭ 6.8 Hz,
H, 2-H ), 3.08 (ddd, J2,2 ϭ 13.8, J2x,3n ϭ 12.0, J2x,3x ϭ 6.1, 1 H,
-H ), 3.92 (dq, J8a,8 ϭ 4.0, average of J3n,8a, J3x,8a and J4,8a
ϭ
and 133.1 (C-6, C-7); being of too low intensity or superimposed
by a signal of 8a, the line of C-4a was not observed. Ϫ B NMR
3
6 Hz, 3 H, BH ), 2.03 (s, 3 H, CH
3
11
[128 MHz, CDCl
3 2 5 2 3
, (C H ) O·BF as external reference]: δ ϭ Ϫ15.7
H, 3-H
n
(
q, JB,H ഠ 96 Hz).
J
1
2
2
1
1
J
x
n
b) Treatment of 7 with NaN(SiMe
SiMe (2.00 g, 10.9 mmol) was added in several portions, under
nitrogen, to a stirred solution of 7 (500 mg, 2.63 mmol) in furan
30 mL) at room temperature, over a period of 3 d. Stirring was
3 2
) in the Presence of Furan: NaN-
x
ϭ
(
3 2
)
.5 Hz, 1 H, 8a-H), 5.14 (br. s, 1 H, 5-H), 5.33 (br. d, J8,8a ϭ 4.0 Hz,
H, 8-H), 5.65 (br. q, average of J3n,4 and J3x,4 and J4,8a ϭ 3.0 Hz,
H, 4-H), 6.18 (dd, J6,7 ϭ 5.7, J7,8 ϭ 1.6 Hz, 1 H, 7-H), 6.42 (dd,
6,7 ϭ 5.7, J5,6 ϭ 2.0, 1 H, 6-H); the assignment is supported by
(
continued for 4 d and the workup was then conducted as in proce-
dure a) to give 8b (34 mg, 7%) as a yellowish oil and a 3:1 mixture
of 8a and 8c (60 mg, 13%) as a highly viscous yellowish oil. Dis-
solved in CDCl
at room temperature, whereas 8a was unchanged.
an NOESY experiment [interactions inter alia between the follow-
ing signal pairs: 1.72 (BH )Ϫ3.92 (8a-H), 1.72 (BH )Ϫ5.33 (8-H),
.03 (CH )Ϫ6.18 (7-H), 2.03 (CH )Ϫ 6.42 (6-H), 3.08 (2-H )Ϫ3.92
8a-H), 5.14 (5-H)Ϫ6.42 (6-H), 5.33 (8-H)Ϫ6.18 (7-H)]. Ϫ
NMR (63 MHz, CDCl ): δ ϭ 21.6 (C-3), 39.7 (CH ), 59.2 (C-2),
6.1 (C-8a), 78.7 (C-8), 80.6 (C-5), 114.2 (C-4), 130.2 (C-7), 132.8
C-4a), 135.3 (C-6); the assignment is based on a C,H COSY spec-
3
3
3
(NMR sample), 8c decomposed over several weeks
2
(
3
3
x
1
3
C
3
3
1
α,6β,6aβ-,
,2,3,5,6,6a-hexahydrocyclobuta[b]pyridine(N؊B)borane (9a, 9b,
(5.78 g, 31.5 mmol) was added under nitro-
gen to a stirred solution of 7 (1.50 mg, 7.90 mmol) in styrene
25 mL) at room temperature. The mixture was stirred for 3 d and
1α,6α,6aβ-,
and
1α,6α,6aα-1-Methyl-6-phenyl-
6
(
1
3 2
and 9c): NaN(SiMe )
11
3 2 5 2 3
trum. Ϫ B NMR [128 MHz, CDCl , (C H ) O·BF as external
reference]: δ ϭ Ϫ9.3 (q, JB,H ഠ 96 Hz). Ϫ IR (KBr): ν˜ ϭ 2957
cm , 2928, 2364, 2313, 2269, 1468, 1460, 1452, 1424, 1378, 1305,
(
Ϫ1
then cautiously treated with water (5 mL). After separation of the
layers and extraction of the aqueous one with diethyl ether (3 ϫ
1
7
1
261, 1170, 1158, 1124, 1105, 1080, 1042, 1019, 1007, 883, 835, 816,
35. Ϫ MS (EI, 70 eV): m/z (%) ϭ 177 (5) [M ], 176 (31), 146 (21),
34 (100), 105 (31), 94 (25), 93 (22), 91 (50), 82 (23), 81 (23), 79
ϩ
4
0 mL), the combined organic fractions were dried with MgSO
and concentrated in vacuo. The residue was purified by flash chro-
matography [SiO , light petroleum ether (b.p. 30Ϫ50 °C)/diethyl
4
(
(
9
27), 77 (39), 72 (21), 65 (25), 56 (61), 55 (23), 51 (26), 44 (34), 42
66), 41 (29), 39 (45). Ϫ C10 16BNO (177.1): calcd. C 67.84, H
.11, N 7.91; found C 67.58, H 8.99, N 7.54.
b: 1H NMR (600 MHz, CDCl
2
H
ether, 5:1] to give, in order of elution, 9c (10 mg, 1%) as a colourless
solid with m.p. 73Ϫ75 °C, followed by a 4:1 mixture of 9c and 9b
(51 mg, 3%), a 1:3 mixture of 9c and 9b (101 mg, 6%), a 1:2 mixture
of 9b and 9a (103 mg, 6%), and 9a (230 mg, 14%), each as a yellow-
ish oil. On treatment with dichloromethane/cyclohexane, the last
fraction gave 9a as beige needles with m.p. 104 °C.
8
3
): δ ϭ 1.70 (very br. q, JB,H
ഠ
9
6 Hz, 3 H, BH ), 2.245 (‘‘ddtd’’, J3,3 ϭ 18.9, J2n,3n ϭ 6.6, J3n,4
3
and J3n,8a ϭ 3.2 and 2.1, J2x,3n ϭ 0.9 Hz, 1 H, 3-H
n
), 2.275
(‘‘ddddd’’, J3,3 ϭ 18.9, J2n,3x ϭ 11.0, J2x,3x ϭ 7.1, J3x,4 and J3x,8a
ϭ
ϭ
ϭ
3.8, 2.0 Hz, 1 H, 3-H
14.3, J2n,3x ϭ 11.0, J2n,3n ϭ 6.6 Hz, 1 H, 2-H
14.3, J2x,3x ϭ 7.1, J2x,3n ϭ 0.9 Hz, 1 H, 2-H
x
), 2.36 (s, 3 H, CH
3
), 3.068 (‘‘ddd’’, J2,2
1
9
a: H NMR (600 MHz, CDCl
3
3
): δ ϭ 1.65 (very broad, BH ), 2.18
n
), 3.093 (‘‘ddd’’, J2,2
(
dm, J3,3 ϭ 18.5 Hz, 1 H, 3-H
x
), 2.28 (dm, J3,3 ϭ 18.5 Hz, 1 H, 3-
x
), 3.24 (br. q, average
H
n
), 2.52 (s, 3 H, CH
3
), 2.71 (m, 1 H, 5-H
x
), 3.02 (dddq, J5,5
ϭ
ϭ
of J3n,8a, J3x,8a and J4,8a ϭ 2.0 Hz, 1 H, 8a-H), 5.08 (br. s, 1 H, 5-
H), 5.35 (dt, J7,8 ϭ 1.9, J5,8 ϭ J8,8a ϭ 0.9 Hz, 1 H, 8-H), 5.92 (br.
q, average of J3n,4, J3x,4 and J4,8a ϭ 2.9 Hz, 1 H, 4-H), 6.43 (dd,
1
1
2
2
4.0, J5n,6 ϭ 9.0, J4,5n ϭ 2.3, average of J3n,5n, J3x,5n, and J5n,6a
.6 Hz, 1 H, 5-H
-H
-H
n
), 3.06 (br. dd, J2,2 ϭ 13.8, J2n,3n ϭ 6.3 Hz, 1 H,
), 3.11 (ddd, J2,2 ϭ 13.8, J2x,3n ϭ 11.6, J2x,3x ϭ 5.3 Hz, 1 H,
), 3.57 (q, average of J5n,6, J5x,6, and J6,6a ϭ 8.7 Hz, 1 H, 6-
n
J6,7 ϭ 5.8, J5,6 ϭ 1.6 Hz, 1 H, 6-H), 6.57 (dd, J6,7 ϭ 5.8, J7,8
ϭ
x
1
.9 Hz, 1 H, 7-H); the assignment is supported by an NOESY ex-
H), 4.35 (m, 1 H, 6a-H), 5.54 (br. quint, Javerage ϭ 2.7 Hz, 1 H, 4-
H), 7.24 (tt, 1 H, p-H), 7.34 (m, 2 H, m-H), 7.45 (m, 2 H, o-H);
the assignment is supported by an NOESY experiment [interac-
periment [interactions inter alia between the following signal pairs:
.70 (BH )Ϫ3.24 (8a-H), 3.24 (8a-H)Ϫ5.35 (8-H), 3.24 (8a-
H)Ϫ6.57 (7-H), 5.08 (5-H)Ϫ6.43 (6-H), 5.35 (8-H)Ϫ6.57 (7-H)]; the
parameters of 2-H , 2-H , 3-H , and 3-H , which give a higher
order spectrum, were obtained by simulation. Ϫ C NMR
1
3
tions inter alia between the following signal pairs: 2.28 (3-H
(CH ), 2.52 (CH )Ϫ3.57 (6-H), 2.71 (5-H )Ϫ7.45 (o-H), 3.11 (2-
)Ϫ4.35 (6a-H), 4.35 (6a-H)Ϫ7.45 (o-H)].
151 MHz, CDCl ): δ ϭ 21.8 (C-3), 35.6 (C-5), 40.3 (CH
n
)Ϫ2.52
n
x
n
x
13
3
3
x
1
3
H
x
Ϫ
C
NMR
3
), 42.0
(100 MHz, CDCl
3 3
): δ ϭ 21.6 (C-3), 39.6 (CH ), 57.8 (C-2), 67.4
(
(
3
(C-8a), 78.5 (C-8), 80.5 (C-5), 117.3 (C-4), 130.1 (C-4a), 134.6 (C-
C-6), 57.8 (C-2), 72.3 (C-6a), 112.5 (C-4), 126.8 (p-C), 127.2 (o-
6), 136.5 (C-7); the assignment is based on a C,H COSY spectrum.
11
C), 128.4 (m-C), 132.1 (C-4a), 141.1 (i-C); the assignment is based
on a C,H COSY spectrum. Ϫ B NMR [128 MHz, CDCl
(C O·BF as external reference]: δ ϭ Ϫ9.9 (q, JB,H ϭ 95 Hz).
Ϫ MS (EI, 70 eV): m/z (%) ϭ 213 (7%) [M ], 212 (20), 199 (80),
Ϫ
2 5 2 3
B NMR [128 MHz, CDCl3, (C H ) O·BF as external refer-
1
1
3
,
ence]: δ ϭ Ϫ9.9 (q, JB,H ഠ 96 Hz). Ϫ MS (EI, 70 eV): m/z (%) ϭ
ϩ
2
H
)
5 2
3
177 (7) [M ], 176 (43), 146 (29), 134 (100), 105 (25), 104 (28), 91
ϩ
(36), 77 (27), 73 (21), 57 (30), 56 (51), 42 (34), 41 (21), 39 (22). Ϫ
ϩ
198 (50), 141 (22), 134 (21), 129 (38), 128 (33), 120 (28), 117 (27),
HRMS ([M Ϫ H] C10H15BNO): calcd. 176.1247; found 176.1246.
1
15 (28), 110 (29), 109 (32), 108 (39), 107 (36), 106 (29), 104 (21),
c: 1H NMR (600 MHz, CDCl
): δ ϭ 2.54 (dddt, J3,3 ϭ 18.0, 94 (49), 92 (20), 91 (54), 82 (35), 81 (29), 80 (21), 77 (21), 56 (100),
3
8
ϩ
J2x,3n ϭ 11.6, J2n,3n ϭ 6.0, average of J3n,4 and J3n,8a ϭ 3.0 Hz, 1
55 (23), 42 (22). Ϫ HRMS ([M Ϫ H] C14
H
19BN): calcd. 212.1611;
n
H, 3-H ), 2.67 (td, J2,2 ϭ J2x,3n ϭ 11.6, J2x,3x ϭ 4.8 Hz, 1 H, 2- found 212.1609.
Eur. J. Org. Chem. 2001, 2665Ϫ2670
2669