C.C. Roberts, J.M. Fritsch / Polyhedron 29 (2010) 1271–1278
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2.2.2.2. Synthesis of magnesium complexes. Under an inert atmo-
sphere, 10 mL of tetrahydrofuran (THF) was added to a Schlenk
flask and the Mg(OBn-4-Me)2 solids were dissolved with rapid stir-
ring. The ketoimine was dissolved in 5 mL of THF and added drop-
wise to flask. An immediate color change from colorless to yellow
color was observed. The reaction was stirred for 4 h. The reaction
volume was reduced in vacuo to approximately 2 mL. The product
was precipitated from solution with hexanes, isolated by filtration,
and dried in vacuo. Reported isolated yields are of analytically pure
samples.
solved in 5 mL of THF and added dropwise to the flask. An immedi-
ate color change from colorless to yellowish-orange was observed
and the reaction was stirred for 4 h. An orange solid was isolated
(0.078 g, 79%). 1H NMR (500 MHz; CDCl3) d 2.85 (s, 6H), 5.72 (s,
2H), 6.76 (dd, J = 1.8, 7.3 Hz, 2H), 6.83 (d, J = 6.5 Hz, 4H), 6.93 (td,
J = 3.0, 7.3 Hz, 4H), 7.07 (dd, J = 3.0, 8.0 Hz, 4H), 7.15 (td, J = 3.0,
8.0 Hz, 2H), 7.22 (dd, J = 2.5, 7.5 Hz, 2H), 7.27 (d, J = 3.5 Hz, 2H),
7.33 (br s, 8H), 7.88 (dd, J = 3.0, 8.0 Hz, 2H); 13C NMR (125 MHz;
CDCl3) d 24.17, 99.41, 119.46, 122.26, 123.14, 125.83, 126.84,
127.11, 127.33, 128.07, 128.85, 129.01, 137.72, 141.31, 141.41,
142.88, 145.46, 157.99, 169.26, 181.11 one signal could not be re-
solved; ESI-HRMS m/z = 751.2959 ([M+H]+), calculated exact mass
2.2.2.3. Synthesis of bis[2-(N-quinolyl)-4-pentanonato]magnesium,
C28H26N4O2Mg, (7). Following procedure B, 4-methylbenzyl alcohol
C50H38N4O2Mg = 751.2923, error: 4.7 ppm; UV (THF) kmax:
(0.077 g, 0.63 mmol) was combined with Mg(nBu)2 (250
lL,
266 nm
431 nm (e
(e
= 23,576 Mꢀ1 cmꢀ1), 341 nm
(e
= 6,962 Mꢀ1 cmꢀ1),
0.25 mmol), stirred overnight, dried in vacuo, and dissolved in
THF. Compound 1 (0.101 g, 0.45 mmol) was dissolved in 5 mL of
THF and added dropwise to the flask. An immediate color change
from colorless to yellow was observed and the reaction was stirred
for 4 h. A canary yellow solid was isolated (0.094 g, 90%). 1H NMR
(200 MHz; CDCl3) d 1.72 (s, 6H), 2.33 (s, 6H), 5.11 (s, 2H), 7.08 (dd,
J = 4.4, 8.0 Hz, 2H), 7.34 (m, 6H), 7.96 (dd, J = 1.7 Hz, 8.4, 2H), 8.25
(dd, J = 1.7, 4.4 Hz, 2H); 13C NMR (50 MHz; CDCl3) d 22.80, 28.14,
101.30, 119.71, 120.84, 121.00, 127.04, 128.84, 137.18, 142.85,
= 27,351 Mꢀ1 cmꢀ1). Crystals suitable for X-ray crystal-
lography were obtained by evaporation of chloroform and hexanes.
2.2.2.7. Synthesis of bis[1-phenyl-1-(N-quinolyl)-3-butanonato]mag-
nesium, C38H30N4O2Mg, (11). Following procedure B, 4-methylben-
zyl alcohol (0.051 g, 0.42 mmol) was combined with Mg(nBu)2
(180 lL, 0.18 mmol), stirred overnight, dried in vacuo, and dis-
solved in THF. Compound 5 (0.098 g, 0.34 mmol) was dissolved
in 5 mL of THF and added dropwise to the flask. An immediate col-
or change from colorless to orange was observed and the reaction
was stirred for 4 h. A light orange solid was isolated (0.082 g, 80%).
1H NMR (500 MHz; CDCl3) d 2.52 (s, 6H), 5.74 (s, 2H), 7.14 (m, 8H),
7.36 (m, 6H), 7.47 (dd, J = 1.0, 7.5 Hz, 2H), 7.55 (t, J = 8.0 Hz, 2H),
7.95 (dd, J = 1.5, 8.5 Hz, 2H), 8.38 (dd, J = 1.5, 4.5 Hz, 2H); 13C
NMR (125 MHz; CDCl3) d 23.19, 76.77, 99.38, 120.24, 120.90,
121.05, 126.91, 127.11, 127.37, 128.63, 128.73, 137.12, 142.86,
145.96, 147.14, 168.77, 186.72; UV (THF) kmax
:
272 nm
(e
e
= 12,915 Mꢀ1 cmꢀ1), 343 nm
= 20,471 Mꢀ1 cmꢀ1).
(e
= 13,072 Mꢀ1 cmꢀ1), 415 nm
(
2.2.2.4. Synthesis of bis[2-(N-2-methylquinolyl)-4-pentanonato]mag-
nesium, C30H30N4O2Mg, (8). Following procedure B, 4-methylbenzyl
alcohol (0.079 g, 0.65 mmol) was combined with Mg(nBu)2 (250
lL,
0.25 mmol), stirred overnight, dried in vacuo, and dissolved in THF.
Compound 2 (0.110 g, 0.46 mmol) was dissolved in 5 mL of THF
and added dropwise to the flask. An immediate color change from
colorless to yellow was observed and the reaction was stirred for
4 h. A canary yellow solid was isolated (0.089 g, 77%). 1H NMR
(200 MHz; CDCl3) d 1.59 (s, 6H), 2.19 (s, 6H), 2.47 (s, 6H), 5.03 (s,
2H), 6.97 (d, J = 8.4 Hz, 2H), 7.26 (m, 6H), 7.84 (d, J = 8.4 Hz, 2H);
13C NMR (50 MHz; CDCl3) d 22.23, 23.47, 27.72, 100.58, 119.73,
121.37, 122.58, 125.91, 126.97, 137.31, 142.98, 144.97, 158.79,
145.63, 147.20, 169.85, 180.68; UV (THF) kmax
:
272 nm
(e
= 13,733 Mꢀ1 cmꢀ1), 428 nm = 25,387 Mꢀ1 cmꢀ1). Crystals
(e
suitable for X-ray crystallography were obtained by evaporation
of chloroform and hexanes.
2.2.2.8. Synthesis of bis[1-phenyl-1-(N-2-methylquinolyl)-3-butano-
nato]magnesium, C40H34N4O2Mg, (12). Following procedure B, 4-
methylbenzyl alcohol (0.045 g, 0.37 mmol) was combined with
Mg(nBu)2 (160
lL, 0.16 mmol), stirred overnight, dried in vacuo,
168.21, 186.43; UV (THF) kmax: 273 nm (
e
e
= 23,294 Mꢀ1 cmꢀ1),
= 28,073 Mꢀ1 cmꢀ1).
and dissolved in THF. Compound 6 (0.100 g, 0.33 mmol) was dis-
solved in 5 mL of THF and added dropwise to the flask. An immedi-
ate color change from colorless to yellowish-orange was observed
and the reaction was stirred for 4 h. A light orange solid was isolated
(0.081 g, 81%). 1H NMR (200 MHz; CDCl3) d 2.37 (s, 6H), 2.51 (s, 6H),
5.53 (s, 2H), 6.97 (m, 12H), 7.48 (m, 6H), 7.89 (d, J = 8.6 Hz, 2H); 13C
NMR (50 MHz; CDCl3) d 22.92, 23.03, 98.23, 120.51, 121.98, 122.68,
126.13, 126.89, 127.23, 127.51, 128.59, 137.60, 142.11, 143.13,
337 nm
(e
= 16,235 Mꢀ1 cmꢀ1), 399 nm
(
Crystals suitable for X-ray crystallography were obtained by evap-
oration of chloroform and hexanes.
2.2.2.5. Synthesis of bis[1,3-diphenyl-1-(N-quinolyl)-3-propanona-
to]magnesium, C48H34N4O2Mg, (9). Following procedure B, 4-meth-
ylbenzyl alcohol (0.043 g, 0.35 mmol) was combined with
Mg(nBu)2 (150
lL, 0.15 mmol), stirred overnight, dried in vacuo,
145.18, 158.35, 169.19, 179.68; UV (THF) kmax
:
273 nm
and dissolved in THF. Compound 3 (0.099 g, 0.28 mmol) was dis-
solved in 5 mL of THF and added dropwise to the flask. An imme-
diate color change from colorless to orange was observed and the
reaction was stirred for 4 h. An orange solid was isolated
(0.072 g, 67%). 1H NMR (200 MHz; CDCl3) d 5.86 (s, 2H), 6.71 (dd,
J = 1.6, 8.0 Hz, 2H), 7.11 (m, 16 H), 7.33 (m, 6H), 7.51 (m, 4H),
7.97 (dd, J = 1.6, 8.0 Hz, 2H), 8.55 (dd, J = 1.6, 4.5 Hz, 2H); 13C
NMR (125 MHz; CDCl3) d 100.52, 119.36, 120.97, 122.36, 126.77,
127.08, 127.35, 128.10, 128.41, 128.60, 128.84, 129.05, 137.30,
141.83, 142.05, 142.64, 146.04, 147.14, 170.33, 182.13; UV (THF)
(e
= 19,035 Mꢀ1 cmꢀ1), 414 nm ( = 28,469 Mꢀ1 cmꢀ1).
e
2.3. Physical measurements
1H NMR (200 MHz) and 13C NMR (50 MHz) spectra of the ketoi-
mines and magnesium complexes were collected with a Bruker FT-
NMR spectrometer. 1H (500 MHz) and 13C (125 MHz) NMR spectra
were collected with a Varian VNMR S500 spectrometer. Electronic
spectra were collected with a Hewlett Packard 8453e Absorbance
Spectrometer (200–1100 nm) with a 4 mL sealed quartz cuvette.
Mass spectrometry data were collected using two different instru-
ments. (1) An Applied Biosystems Qstar Elite Quadrupole Time of
Flight Instrument controlled by ANALYST 2.0 software. Samples were
infused directly into the Turbo Ionspray source using the built-in
syringe pump. The internal standard for accurate mass determina-
tion was either renin substrate (Sigma R8129) or Met-Arg-Phe-Ala
acetate salt (Sigma M1170). (2) A Waters LCT Premier XE Time of
Flight Instrument controlled by MASSLYNX 4.1 software. Samples
kmax: 264 nm (
e e
= 13,401 Mꢀ1 cmꢀ1), 344 nm ( = 3,197 Mꢀ1 cmꢀ1),
443 nm (
e
= 16,410 Mꢀ1 cmꢀ1).
2.2.2.6. Synthesis of bis[1,3-diphenyl-1-(N-2-methylquinolyl)-3-pro-
panonato]magnesium, C50H38N4O2Mg, (10). Following procedure B,
4-methylbenzyl alcohol (0.042 g, 0.34 mmol) was combined with
Mg(nBu)2 (150
lL, 0.15 mmol), stirred overnight, dried in vacuo,
and dissolved in THF. Compound 4 (0.099 g, 0.27 mmol) was dis-