rac-Lactide
FULL PAPER
C4,4’), 73.0 (d, J
U
(t, J=6 Hz, 1H; Ph H), 6.41 (t, J=6 Hz, 1H; Ph H), 6.14, (d, J=6 Hz,
À
À
À
À
À
1H; Ph H) 5.35 (s, 2H; Pz H), 4.21 (s, 3H; OCH3), 2.45 (s, 6H; Pz
À
CH3), 1.76 (s, 6H; Pz CH3), 0.39 (s, 18H; Si
A
À
À
À
1H; Y CH2), 0.03 (d, J=3 Hz, 1H; Y CH2), À0.07 (d, J=3 Hz, 1H; Y
CH2), À0.10 ppm (d, J=3 Hz, 1H; Y CH2); 13C NMR (75 MHz, C6D6)
À
Synthesis of 2: Exposure of dichloromethane solution of compound 1 to
d=152.7 (d, J=16.5 Hz, 1C; C3,3’ or C5,5’) 149.7 (s, 2C; C3,3’ or C5,5’),
146.0 (d, J=6.75 Hz, 2C; Ph), 139.8 (d, J=9 Hz, 1C; Ph), 132.9 (d, J=
9 Hz, 4C; Ph), 131.7 (d, J=2.25 Hz, 2C; Ph), 127.0 (s, 1C; Ph), 123.4 (s,
1C; Ar), 121.4 (d, J=10.5 Hz, 1C; Ar), 118.5 (s, 1C; Ar), 111.3 (s, 1C;
Ar), 105.5 (s, 2C; C4,4’), 68.0 (s, 1C; ipso-C), 59.16 (s, 1C; OCH3), 34.1 (s,
oxygen at room temperature for 2 d gave rise to compound 2 (yield:
1
96%). H NMR (300 MHz, CDCl3): d=7.71 (s, 1H; Ph H), 7.68 (s, 1H;
À
Ph H), 7.67 (s, 1H; Ph H), 7.65 (s, 1H; Ph H), 7.46 (t, J
2H; Ph H), 7.40–7.34 (td, 3J
À
H), 6.95 (d, J
N
À
À
À
Pz CH3), 2.04 ppm (s, 6H; Pz CH3); 13C NMR: (75 MHz, CDCl3): d=
148.6 (s, 2C; C3,3’ or C5,5’) , 142.0, 141.9 (s, 2C; C3,3’ or C5,5’), 132.4, 132.3,
132.1, 132.0, 131.9, 130.6, 128.7, 128.5 (Ph), 107.7 (s, 2 C; C4,4’), 73.5 (d, J-
1C; Y CH2), 33.6 (s, 1C; Y CH2), 15.1 (s, 2C; 3-CH3 Pz), 11.9 (s, 2C;
5-CH3 Pz), 5.0 ppm (s, 6C; Si
161.9 MHz): d=13.63 ppm; elemental analysis calcd (%) for
C38H53N5OPSi2Y: C 59.13, H 6.92, N 9.07; found: C 59.07, H 6.83, N 8.96.
Single crystals suitable for X-ray structural analysis were grown from
mixed hexane/THF solution at À308C.
À
(CH3)3); 31P NMR (C6D6, 258C,
À
ACHTUNGTRENNUNG
(P,C)=82.5 Hz, 1C), 13.8 (s, 2C; CH3), 11.6 ppm (s, 2C; CH3); 31P NMR
(161.9 MHz, CDCl3): d=26.77 ppm (s, 1P); MS: m/z: 405.2 [M+H]+; el-
emental analysis calcd (%) for C23H25N4OP: C 68.30, H 6.23, N 13.85;
found: C 68.18, H 6.13, N 13.71.
Synthesis of compound 3: 2-Azidoanisole (9.5 mmol) in dichloromethane
(10 mL) was added dropwise to a stirred solution of 1 (9.5 mmol) in di-
chloromethane (20 mL) in a glovebox. The resulting reddish-brown solu-
tion was stirred for 1 d followed by heating at 508C for another day
under N2 atmosphere. The reaction mixture was concentrated under re-
duced pressure to approximately 10 mL. Then it was added dropwise to
stirred ethyl acetate (50 mL) to generate a brown suspension. After fil-
tration, a gray solid was obtained, which was washed by a small amount
of ethyl acetate, followed by drying under reduced pressure at room tem-
perature (yield: 74%). 1H NMR (300 MHz, CDCl3): d=7.61–7.40 (m,
Acknowledgements
We thank the financial support from National Nature Science Foundation
of China (grant nos. 20934006 and 51021003).
[2] Z. Zhang, D. Cui, B. Wang, B. Liu, Y. Yang, Struct. Bonding (Berlin)
2010, 137, 49–108.
[5] S. Bambirra, M. W. Bouwkamp, A. Meetsma, B. Hessen, J. Am.
10H; Ph H), 6.77 (td, J
AHCTUNGTRENNUNG
(H,H)=7.5 Hz, 1H; Ar H), 6.65 (td, 1H, 3J-
À
À
À
A
U
N
À
(H,H)=1.5 Hz, 1H; Ar H), 6.41 (d, J
A
À
(s, 1H, CH), 5.67 (s, 2H; Pz H), 4.04 (s, 3H; ArOCH3), 2.47 (s, 6H; Pz
CH3), 1.91 ppm (s, 6H; Pz CH3); 13C NMR (100 MHz, CDCl3) d=152.4,
À
152.2, 151.5, 139.3, 137.9, 132.9, 131.9, 131.8, 128.9, 128.8, 125.4, 124.6,
122.2, 122.1, 120.6, 118.6, 109.7, 106.2, 65.6, 64.5, 55.3, 13.7, 10.6 ppm;
MS: m/z: 510.2 [M+H]+; elemental analysis calcd (%) for C30H32N5OP:
C 70.71, H 6.33, N 13.74; found: C 70.58, H 6.22, N 13.65.
Synthesis of 4a: Trialkyl yttrium complex [YACHTNUTRGENN(UG CH2SiMe3)3ACHTUNGTNER(NUGN thf)2] (0.2 g,
0.4 mmol) was dissolved in dry hexane and cooled to À308C. A toluene
suspension of compound 1 at À308C was added into the stirred trialkyl
yttrium solution. After overnight reaction at this temperature, the reac-
tion mixture was concentrated to a small portion. Colorless crystals pre-
cipitated at the bottom of the bottle from a saturated toluene/hexane so-
lution. The solids were dried in vacuo at room temperature to give com-
[10] For reviews on heteroscorpionate ligands, see: a) A. Otero, J.
Fernꢄndez-Baeza, A. AntiÇolo, J. Tejeda, A. Lara-Sꢄnchez, Dalton
[11] a) R. Hoffmann, Angew. Chem. 1982, 94, 725–739; Angew. Chem.
Howe, C. S. Tredget, S. C. Lawrence, S. Subongkoj, A. R. Cowley, P.
[12] a) I. Kuzu, I. Krummenacher, I. J. Hewitt, Y. Lan, V. Mereacre,
[13] A. Otero, J. Fernꢄndez-Baeza, A. Lara-Sꢄnchez, C. Alonso-Moreno,
I. Mꢄrquez-Segovia, L. F. Sꢄnchez-Barba, A. M. Rodrꢅguez, Angew.
1
plex 4a in 62% yield. H NMR (C6D6, 258C, 300 MHz): d=7.13–7.13 (m,
À
À
À
À
4H; Ph H), 6.92 (m, 6H; Ph H), 6.0 (d, 1H; C H), 5.17 (s, 2H; Pz H),
À
2.54 (s, 6H; CH3), 1.32 (s, 6H; CH3), 0.54 (s, 18H; Si
G
À
À
9H; Si
(CH3)3), 0.13 ppm (s, 6H; Y CH2); 13C NMR (C6D6, 258C,
100 MHz): d=154.1 (s; C3,3’ or C5,5’), 140.6 (s; C3,3’ or C5,5’), 134.3, 134.1,
131.7, 129.6, 129.5 (Ph), 108.3 (s; C4,4’), 68.3 (s; P C), 38.1 (d, J
(Y,C)=
À
À
À
100 Hz; Y C), 36.1 (d, J
CH3), 5.7 (s; Si(CH3)3), 5.4 ppm (s; Si
(Y,C)=100 Hz; Y C), 15.8 (s; CH3), 10.9 (s;
G
(CH3)3); 31P NMR (C6D6, 258C,
161.9 MHz): d=1.05 ppm; elemental analysis calcd (%) for
C35H58N4PSi3Y: C 56.88, H 7.91, N 7.58; found: C 56.78, H 7.79, N 7.48.
Single crystals suitable for X-ray analysis were obtained from saturated
toluene/hexane solution at À308C.
Complex 5a: Yield: 57%; 1H NMR (C6D6, 258C, 300 MHz): d=8.07 (s,
À
À
4H; Ph H), 7.06–6.97 (m, 6H; Ph-H), 5.40 (s, 2H; Pz H), 3.61 (s, 4H;
À
À
THF), 2.16 (s, 6H; Pz CH3), 2.10 (s, 6H; Pz CH3), 1.23 (s, 4H; THF),
0.61 (s, 18H; Si
A
258C, 100 MHz): d=148.8, 145.2, 145.1 (C3,3’ and C5,5’), 132.7, 132.6,
689–695; c) Y. Kikkawa, H. Abe, T. Iwata, Y. Inoue, Y. Doi, Bio-
131.5 (Ph), 105.0 (C4,4’), 70.6 (THF), 67.3 (ipso-C P), 31.4
(Y CH2), 31.0
À
À
À
À
À
(Y CH2), 25.2 (THF), 14.5 (3-CH3 Pz), 12.2 (5-CH3 Pz), 5.0 ppm (Si-
ACHTUNGTRENNUNG
(CH3)3); 31P NMR (C6D6, 258C, 161.9 MHz): d=34.24 ppm; elemental
analysis calcd (%) for C35H54N4O2PSi2Y (%): C 56.89, H 7.37, N 7.58;
found: C 56.78, H 7.29, N 7.50. Single crystals suitable for X-ray analysis
were obtained from saturated toluene/hexane solution at À308C.
[17] For reviews on ring-opening polymerization of lactide, see: a) N.
Ajellal, J.-F. Carpentier, C. Guillaume, S. M. Guillaume, M. Helou,
Complex 6a: Yield: 47%; 1H NMR (400 MHz, CDCl3, 258C): d=7.49
À
À
À
(br, 4H; Ph H), 6.92 (br, 6H; Ph H), 6.60 (d, J=6 Hz, 1H; Ph H), 6.51
Chem. Eur. J. 2011, 17, 11520 – 11526
ꢀ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
11525