J. Okuda et al.
release of propene. High thermodynamic stability of the car-
bometalated products or high activation barriers for CÀH
drying under reduced pressure, the product was obtained as a dark red-
brown, glossy powder (232 mg, 0.78 mmol, 96%). H NMR (400 MHz,
1
[
4
9
8 2
D ]THF, 258C): d=1.77 (m, 4H; THF), 2.37 (s, 4H; CH -Ca), 3.62 (m,
bond activation are demonstrated by a long reaction time
for 5 and the persistence of intermediates 5a and 5b in the
reaction mixture. This also holds for 2–4, but to a much
lesser extent. The transformations of carbometalated prod-
ucts giving CÀH bond activated products may hint at rever-
3
3
H; THF), 5.08 (t,
.0 Hz, 2H; CH-3), 6.23 (t, J ACHTUNTGRNENUGN( H,H)=7.6 Hz, 2H; CH-4), 7.11 ppm (d, J-
J AHCTUNGTRENNUGN( H,H)=5.9 Hz, 2H; CH-5), 5.83 (d, J ACHTUNGTRENNUNG( H,H)=
3
3
1
3
1
8
AHCTUNGTNERNUG( H,H)=5.8 Hz, 2H; CH-6); C{ H} NMR (100 MHz, [D ]THF, 258C):
d=26.35 (THF), 55.32 (CH
CH-3), 132.73 (CH-4), 148.21 (C-2), 148.23 ppm (CH-6); metal analysis
calcd (%) for C20 (368.53): Ca 8.68; found: Ca 8.84.
(3b·(THF) ): solution of
2
-Ca), 68.22 (THF), 98.76 (CH-5), 116.36
(
H
2 2
28CaN O
sibility of the initial insertion step. An indication of reversi-
ble pyridine functionalization by organoruthenium catalysts
[
Ca(4-CH
2
-C
5
H
4
N)
2
A
T
N
T
N
U
G
2
]
A
H
U
G
R
N
U
G
2
A
3
(152 mg,
1
0
.63 mmol) in THF (2 mL) was added to a stirred solution of 1 (100 mg,
.82 mmol) in THF (8 mL). The reaction mixture was heated under
[12e,33]
has recently been reported.
Interestingly, allylic rear-
rangements at pyridine rings were described long ago for al-
lylmagnesium halides, and were suggested to proceed via
reflux conditions for 18 h at 708C. A color change to black and the for-
mation of a dark precipitate was observed. After removal of all volatiles,
the product was washed first with pentane and then with THF (ca.
(
s.
intramolecular) Cope- and Claisen-like rearrangement-
2
0 mL). Drying of the remaining solid under reduced pressure afforded
[
21a–d,34]
These reports are consistent with the reactivity pat-
the product as light-brown powder (178 mg, 0.48 mmol, 59%).
a
[25]
1
terns described in this contribution and our earlier work.
H NMR (400 MHz, [D ]THF, 258C): d=1.77 (m, 8H; THF), 2.84 (s,
8
3
4
3
2
1
H; CH
,5), 6.32 ppm (br, 4H; CH-2,6); C{ H} NMR (100 MHz, [D
58C): d=26.55 (THF), 68.39 (THF), 71.79 (CH -Ca), 110.21 (CH-3,5),
41.69 (CH-2,6), 150.69 ppm (C-4); metal analysis calcd (%) for
(368.53): Ca 10.88; found: Ca 10.98.
N-6-CH (THF) ] (4b·(THF) ; n=0–1): Method a: A
2
-Ca), 3.62 (m, 8H; THF), 5.26 (d, JACHTGNRUETNNUG
1
3
1
8
2
Conclusion
20 2 2
C H28CaN O
A general procedure for the regioselective production of al-
lylated and calciated pyridines and quinolines using bis-
ACHTUNGTRENNUNG( allyl)calcium (1) has been achieved. The simple protocol in-
[
Ca(2-CH
2
-C
5
H
3
3
)
2
A
H
U
G
R
N
U
n
A
H
U
G
E
N
N
n
solution of 4 (263 mg, 2.45 mmol) in THF (3 mL) was added to a stirred
solution of 1 (150 mg, 1.23 mmol) in THF (12 mL). The reaction mixture
was stirred for 24 h at 258C, whereupon a color change from orange to
red was observed. After removal of all volatiles, washing with pentane,
and drying under reduced pressure, the product was obtained as a dark
volves stirring a stoichiometric amount of 1 with the corre-
sponding N-heterocycle in THF, removal of all volatiles, and
washing of the air- and moisture-sensitive products. Due to
essentially quantitative yields, side product formation or
contamination of the products is minimal. Methyl groups at
ortho- or para-positions on the N-heterocycle are easily
metalated by 1 with concomitant release of propene, but
dearomatized carbometalation products are formed exclu-
sively in their absence.
1
orange powder (n=0.75, 356 mg, 1.16 mmol, 95%). H NMR (400 MHz,
[D
CH
8
]THF, 258C): d=1.78 (m, 3H; THF), 1.88 (s, 6H; CH
3
), 2.32 (s, 4H;
3
2
3
-Ca), 3.64 (m, 3H; THF), 5.11 (d, J ACHTGNURTEN(NUGN H,H)=6.3 Hz, 2H; CH-5), 5.76
3
(
d, J ACHTUNGTRENUN(GN H,H)=8.5 Hz, 2H; CH-3), 6.28 ppm (dd, J ACHTUTGNENRNUG
1
3
1
2
2
H; CH-4); C{ H} NMR (100 MHz, [D
6.22 (THF), 55.79 (CH
8
3
2
133.27 (CH-4), 156.19 (C-6), 165.18 (C-2); metal analysis calcd (%) for
0.75 (306.45): Ca 13.08; found: Ca 13.36.
17 2
C H22CaN O
Method b: A solution of 1 (50 mg, 0.41 mmol) in THF (4 mL) was added
to a solution of 4 (88 mg, 0.82 mmol) in THF (1 mL). The reaction mix-
ture was stirred at 258C for 24 h, which resulted in a darkening of the
orange color. Pentane (50 mL) was added, whereupon a slight clouding
was observed. Reducing the volume of this mixture to <5 mL resulted in
the precipitation of a yellow solid, which was isolated by filtration. After
washing with pentane and drying under reduced pressure, the base-free
product 4b was obtained as a yellow powder (n=0, 24 mg, 0.10 mmol,
Experimental Section
General considerations: All operations were performed under an inert
atmosphere of argon using standard Schlenk-line or glove-box tech-
niques. [D
ketyl prior to use. D
3), 2,6-lutidine (4), 4-tert-butylpyridine (5), quinoline (8), and isoquino-
line (9) were dried over CaH and distilled under argon prior to use. 2,2’-
8
]THF was distilled under argon from sodium/benzophenone
2
3%). Single crystals of 4b·
bined filtrate and washings to À308C. The yield (47 mg, 0.12 mmol,
9%) is given for the bis(THF) adduct, 4b·(THF) , as drying under
3
ACHTUNGTNERUNNG( THF) were obtained by cooling the com-
2
O was used as purchased. 2-Picoline (2), 4-picoline
(
2
A
H
U
T
E
N
N
A
H
U
G
R
N
N
2
2
argon at ambient pressure resulted in the rapid loss of one THF molecule
per formula unit to give a powder instead of orange crystals. Metal analy-
sis calcd (%) for C14H16CaN (252.37): Ca 15.88; found: Ca 15.44.
2
Bipyridine (6) and acridine (7) were purified by vacuum sublimation.
THF and pentane were purified using an MB SPS-800 solvent purifica-
tion system. NMR spectra were recorded on a Bruker DRX400 spec-
1
13
1
trometer ( H, 400.1 MHz; C{ H}, 100.6 MHz) at 258C unless otherwise
During the course of the reaction, the insertion product 4a and the
double-activation product 4c were observed in the NMR spectra. Spec-
1
13
1
stated. Chemical shifts in H and C{ H} NMR spectra were referenced
internally using the residual solvent resonances and are reported relative
to tetramethylsilane. Due to extreme sensitivity, no elemental analyses
could be performed. Instead, metal titration by the following procedure
was applied. A portion of the product (10–30 mg) was dissolved in THF
[
25]
troscopic data have been reported for 4a. Data for 4c are given for in
1
situ formed compound. [Ca(2,6-CH
[D ]THF, 258C): d=2.04 (br, 4H; CH
CH-3,5), 6.10 ppm (t,
(100 MHz, [D ]THF, 258C): d=47.59 (br; CH
135.32 (CH-4), 168.10 ppm (C-2,6).
Ca{2-C N-4-C(CH (THF) ] (5c·
pyridine (221 mg, 1.63 mmol) in THF (5 mL) was added to a solution of
(100 mg, 0.82 mmol) in THF (15 mL). The dark reaction mixture was
2
-C
), 4.89 (brd, J
(H,H)=7.8 Hz, 1H; CH-4); C{ H} NMR
), 93.92 (br; CH-3,5),
5 3
H N)] (4c): H NMR (400 MHz,
3
8
2
ACHTUNGTRENNU(GN H,H)=8.3 Hz, 2H;
3
13
1
JACHTUNGTRENNUNG
(
0.5–1 mL) and hydrolyzed by slow addition of water. After the addition
8
2
of 25% aqueous ammonia solution (1–2 mL), the total volume was in-
creased to 20–30 mL by the addition of water. An indicator buffer tablet
was dissolved and the solution was titrated with a 0.01m solution of
EDTA disodium salt until the transition point from red to green was ob-
served.
[
5
H
3
A
H
N
T
E
N
N
3
)
3
}
2
A
H
U
T
E
N
N
2
2
ACHTUNGTNRENUNG( THF) ): A solution of 4-tert-butyl-
1
stirred for 7 days at 258C. After removal of all volatiles, washing with
[
(
Ca(2-CH
152 mg, 1.63 mmol) in THF (5 mL) was added to a stirred solution of
(C ] (1) (100 mg, 0.82 mmol) in THF (10 mL). Heating under
2
-C
5
H
4
N)
2
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(THF)] (2b·
A
T
N
T
E
N
N
(THF)):
A
solution of 2-picoline
pentane, and drying under reduced pressure, the product was obtained as
1
a
dark powder (373 mg, 0.82 mmol, >99%). H NMR (400 MHz,
[
Ca
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
3
H
5
)
2
8 3
[D ]THF, 258C): d=0.90 (s, 18H; CH ), 1.77 (m, 8H; THF), 3.62 (m,
3
4
reflux conditions for 3 h at 708C resulted in a color change from orange
to dark red. After removal of all volatiles, washing with pentane, and
8H; THF), 4.09 (dd, J
A
H
U
G
R
N
U
G
ACHTUNGTNERNUNG( H,H)=1.8 Hz, 2H; CH-5), 5.29
4
3
(d, J
A
H
U
G
E
N
N
ACHTUNGTRENNUNG( H,H)=6.8 Hz, 2H; CH-
12120
ꢀ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2011, 17, 12115 – 12122