ꢀ-Caprolactone Polymerization of Al and Zn Complexes
Organometallics, Vol. 27, No. 7, 2008 1631
Ph), 7.41-7.50 (m, 3H, Ph + Py). 13C NMR (CDCl3): δ 3.77,
13.94, 15.13, 98.01, 100.43, 112.59, 119.85, 127.69, 128.05, 128.51,
138.48, 141.49, 144.97, 145.98, 151.46, 158.06, 170.33. Anal. Calcd
for C21H25ClN4SiZn: C, 54.55; H, 5.45; N, 12.12. Found: C, 54.39;
H, 5.47; N 11.92.
130.14, 137.80, 140.55, 143.04, 145.33, 155.41, 156.16, 170.18.
Anal. Calcd for C22H28AlClN4Si: C, 60.19; H, 6.43; N, 12.76.
Found: C, 60.07; H, 6.41; N, 13.08.
Reaction of [Zn(Cl){2-(3,5-Me2C3HN2)-6-{N(SiMe3)C(Ph)d
CH}C5H3N}] with AlEt3. To a stirred solution of 4 (0.17 g, 0.37
mmol) in toluene (10 mL) was added dropwise a solution of AlEt3
(0.22 mL, a 1.8 M solution in hexane, 0.40 mmol) at about -80
°C. The resulting solution was warmed to room temperature and
stirred overnight. The solution was filtered and the filtrate was
concentrated to give yellow orange crystals of 6b (0.10 g, 60%),
mp 128-130 °C. 1H NMR (C6D6): δ 0.44 (s, 9H, SiMe3), 0.47 (q,
J ) 8.1 Hz, 2H, CH2), 1.29 (t, J ) 8.1 Hz, 3H, Me), 1.51 (s, 3H,
Me), 2.93 (s, 3H, Me), 5.33 (s, 1H, pyrazolyl), 5.98 (d, J ) 8.1
Hz, 1H, Py), 6.06 (s, 1H, CH), 6.50 (d, J ) 8.1 Hz, 1H, Py), 6.82
(d, J ) 8.1 Hz, 1H, Py), 7.18-7.24 (m, 3H, Ph), 7.91-7.95 (m,
2H, Ph). 13C NMR (C6D6): δ 4.73, 4.88, 11.31, 14.05, 17.22,
101.06, 102.74, 114.69, 119.63, 127.91, 128.23, 129.34, 129.44,
130.24, 137.68, 140.48, 143.12, 145.20, 155.75, 156.20, 170.32.
Anal. Calcd for C23H30AlClN4Si: C, 60.98; H, 6.67; N, 12.37.
Found: C, 60.34; H, 6.80; N 11.90.
Preparation of [Zn(Me){2-(3,5-Me2C3HN2)-6-{N(SiMe3)-
C(Ph)dCH}C5H3N}] (5a). To a stirred solution of 4 (0.20 g, 0.43
mmol) in toluene (10 mL) was added dropwise a solution of LiMe
(0.28 mL, a 1.6 M solution in Et2O, 0.45 mmol) at about -20 °C.
The resulting solution was warmed to room temperature and stirred
overnight. Solvents were removed in vacuo and the residue was
dissolved in hexane. The solution was filtered and the filtrate was
concentrated to give yellow crystals of 5a (0.12 g, 63%), mp
1
159-161 °C. H NMR (C6D6): δ -0.25 (s, 3H, ZnMe), 0.31 (s,
9H, SiMe3), 1.71 (s, 3H, Me), 2.29 (s, 3H, Me), 5.37 (s, 1H,
pyrazolyl), 5.54 (s, 1H, CH), 5.90 (d, J ) 7.5 Hz, 1H, Py), 6.35
(d, J ) 8.4 Hz, 1H, Py), 6.78 (t, J ) 8.1 Hz, 1H, Py), 7.14-7.22
(m, 3H, Ph), 7.57-7.60 (m, 2H, Ph). 13C NMR (C6D6): δ -11.64,
3.93, 13.56, 13.66, 98.68, 101.75, 111.09, 118.79, 127.92, 128.79,
137.29, 140.18, 147.45, 150.46, 159.06, 170.15. Anal. Calcd for
C22H28N4SiZn: C, 59.79; H, 6.39; N, 12.68. Found: C, 59.66; H,
6.32; N, 12.51.
Reaction of [Li{2-{N(SiMe3)C(Ph)dCH}-6-(3,5-Me2C3HN2)-
C5H3N}] (3) with Al(Me)Cl2. AlMe3 (0.17 mL, a 2.2 M solution in
hexane, 0.37 mmol) was added to a suspension of AlCl3 (0.10 g,
0.75 mmol) in toluene (10 mL) at room temperature with stirring.
The mixture was stirred for 5 h and added to a stirred solution of
3 (0.37 g, 1 mmol) in toluene (15 mL) at about -80 °C. The
resulting solution was stirred at room temperature for 15 h and
heated at 90 °C (bath temperature) for 6 h. The solution was cooled
to room temperature and filtered. The filtrate was concentrated to
form orange crystals of 6a (0.24 g, 55%). 1H NMR (C6D6): δ -0.13
(s, 3H, AlMe), 0.41 (s, 9H, SiMe3), 1.47 (s, 3H, Me), 2.87 (s, 3H,
Me), 5.29 (s, 1H, pyrazolyl), 5.91 (d, J ) 7.8 Hz, 1H, Py), 6.02 (s,
1H, CH), 6.45 (d, J ) 8.1 Hz, 1H, Py), 6.77 (t, J ) 7.8 Hz, 1H,
Py), 7.12-7.22 (m, 3H, Ph), 7.86-7.89 (m, 2H, Ph).
Preparation of 2-(3,5-Me2C3HN2)-6-(Ph2PCH2)C5H3N (7). To
a stirred solution of 2-methyl-6-(3,5-dimethyl-1H-pyrazol-1-yl)py-
ridine (0.43 g, 2.3 mmol) in THF (10 mL) was added dropwise a
solution of LDA (2.5 mmol, prepared from Pri2NH and LiBun in
THF) at about -60 °C. The resulting solution was stirred at -20
°C for 20 min and then recooled to about -80 °C. To the solution
Ph2PCl (0.47 mL, 2.5 mmol) dissolved in THF (5 mL) was added.
The resulting solution was stirred at -80 °C for 15 min and then
at room temperature overnight. Solvents were removed in vacuo
and the residue was extracted with toluene. The extract was filtered
and the solvent was removed from the filtrate. The residual oil was
dissolved with Et2O and concentrated to afford colorless crystals
of 7 (0.45 g, 53%), mp 119-120 °C. 1H NMR (CDCl3): δ 2.15 (s,
3H, Me), 2.36 (s, 3H, Me), 3.47 (s, 2H, CH2), 5.79 (s, 1H,
pyrazolyl), 6.73 (d, J ) 7.5 Hz, 1H, Py), 7.15-7.17 (m, 6H, Ph),
7.27-7.31 (m, 4H, Ph), 7.40 (t, J ) 7.8 Hz, 1H, Py), 7.52 (d, J )
8.1 Hz, 1H, Py). 13C NMR (CDCl3): δ 13.51, 14.56, 38.41 (d, J )
16.5 Hz), 108.66, 112.52, 120.13 (d, J ) 6 Hz), 128.24 (d, J ) 6.5
Hz), 128.55, 132.53, 132.78, 137.97, 138.13, 138.18, 141.57,
149.35, 152.93, 156.11 (d, J ) 8.2 Hz). 31P NMR (CDCl3): δ
-14.84. Anal. Calcd for C23H22N3P: C, 74.38; H, 5.97; N, 11.31.
Found: C, 75.07; H, 6.18; N, 11.12.
Preparation of [Zn(Et){2-(3,5-Me2C3HN2)-6-{N(SiMe3)C(Ph)d
CH}C5H3N}] (5b). To a stirred solution of 4 (0.11 g, 0.24 mmol)
in toluene (10 mL) was added dropwise a solution of LiEt (0.32
mmol, prepared from EtBr and Li in Et2O) at about -20 °C. The
resulting solution was warmed to room temperature and stirred
overnight. Solvents were removed in vacuo and the residue was
dissolved in hexane. The solution was filtered and the filtrate was
concentrated to give yellow orange crystals of 5b (0.07 g, 65%),
mp 112-114 °C. 1H NMR (C6D6): δ 0.31 (s, 9H, SiMe3), 0.62 (q,
J ) 8.1 Hz, 2H, CH2), 1.52 (t, J ) 8.1 Hz, 3H, CH3), 1.75 (s, 3H,
Me), 2.28 (s, 3H, Me), 5.37 (s, 1H, pyrazolyl), 5.56 (s, 1H, CH),
5.93 (d, J ) 7.5 Hz, 1H, Py), 6.34 (d, J ) 8.1 Hz, 1H, Py), 6.79
(t, J ) 8.1 Hz, 1H, Py), 7.14-7.22 (m, 3H, Ph), 7.60-7.63 (m,
2H, Ph). 13C NMR (C6D6): δ 2.20, 3.87, 13.57, 13.69, 13.74, 98.85,
101.51, 111.09, 118.66, 127.92, 127.96, 128.84, 137.38, 140.08,
146.32, 147.49, 150.50, 158.98, 170.31. Anal. Calcd for
C23H30N4SiZn: C, 60.58; H, 6.63; N, 12.29. Found: C, 60.27; H,
6.57; N 12.32.
Reaction of [Zn(Cl){2-(3,5-Me2C3HN2)-6-{N(SiMe3)C(Ph)d
CH}C5H3N}] with LiHBEt3. To a stirred solution of 4 (0.17 g,
0.37 mol) in THF (10 mL) was added dropwise a solution of
LiHBEt3 (0.38 mL, a 1 M solution in THF, 0.38 mmol) at about
-80 °C. The resulting solution was warmed to room temperature
and stirred overnight. Volatiles were removed in vacuo and the
residue was dissolved in hexane. The solution was filtered and the
filtrate was concentrated to give yellow orange crystals of 5b (0.11
g, 66%), mp 110-112 °C. 1H NMR (C6D6): δ 0.31 (s, 9H, SiMe3),
0.63 (q, J ) 8.1 Hz, 2H, CH2), 1.53 (t, J ) 8.1 Hz, 3H, Me), 1.73
(s, 3H, Me), 2.28 (s, 3H, Me), 5.38 (s, 1H, pyrazolyl), 5.55 (s, 1H,
CH), 5.92 (d, J ) 7.5 Hz, 1H, Py), 6.34 (d, J ) 8.1 Hz, 1H, Py),
6.79 (t, J ) 8.1 Hz, 1H, Py), 7.17-7.25 (m, 3H, Ph), 7.61-7.67
(m, 3H, Ph).
Reaction of [Zn(Cl){2-(3,5-Me2C3HN2)-6-{N(SiMe3)C(Ph)d
CH}C5H3N}] with AlMe3. To a stirred solution of 4 (0.20 g, 0.43
mol) in toluene (10 mL) was added dropwise a solution of AlMe3
(0.22 mL, a 2.2 M solution in hexane, 0.48 mmol) at about -80
°C. The resulting solution was warmed to room temperature and
stirred overnight. The solution was filtered and the filtrate was
concentrated to give orange crystals of 6a (0.12 g, 63%), mp
Preparation of 2-(3,5-Me2C3HN2)-6-{PhNdP(Ph)2CH2}C5H3N
(8). To a stirred solution of 7 (0.30 g, 0.81 mmol) in THF (10 mL)
was added dropwise PhN3 (0.12 g, 1.00 mmol) at room temperature.
The mixture was stirred for 3 h and then solvent was removed in
vacuo. The residue was dissolved in toluene and filtered. The filtrate
was concentrated to give colorless crystals of 8 (0.30 g, 80%), mp
1
204-206 °C dec. H NMR (C6D6): δ -0.13 (s, 3H, AlMe), 0.43
1
(s, 9H, SiMe3), 1.54 (s, 3H, Me), 2.89 (s, 3H, Me), 5.35 (s, 1H,
pyrazolyl), 5.98 (d, J ) 7.8 Hz, 1H, Py), 6.04 (s, 1H, CH), 6.49
(d, J ) 8.1 Hz, 1H, Py), 6.84 (t, J ) 7.8 Hz, 1H, Py), 7.14-7.22
(m, 3H, Ph), 7.88-7.90 (m, 2H, Ph). 13C NMR (C6D6): δ 1.44,
4.73, 14.05, 17.02, 101.31, 102.74, 114.60, 119.70, 128.87, 129.34,
209-211 °C. H NMR (C6D6): δ 2.39 (s, 6H, Me), 3.99 (d, J )
13.5 Hz, 2H, CH2), 5.93 (s, 1H, pyrazolyl), 6.98-7.18 (m, 9H, Ph
+ Py), 7.25-7.40 (m, 4H, Ph + Py), 7.80-7.87 (m, 4H, Ph), 8.03
(d, J ) 8.1 Hz, 1H, Py). 13C NMR (C6D6): δ 13.84, 14.83, 38.58
(d, J ) 60.1 Hz), 109.18, 113.33 (d, J ) 2.7 Hz), 117.80, 122.17