Carenium-Calkyl Bond Making and Breaking
J. Am. Chem. Soc., Vol. 123, No. 30, 2001 7245
stirring over 24 h, the formed suspension was filtered (Celite) and the
red filtrate was evaporated to dryness. Analysis of the crude product
showed ca. 50% unreacted 2c. Acetone (10 mL) and additional EtBr
(5 mL) were added, and the reaction was left for 7 days, during which
again a precipitate formed. This was removed and the residual solution
treated with pentane. Repeated dissolving in CH2Cl2 (5 mL) and
precipitating with pentane (30 mL) afforded 4a as a red solid which
was still contaminated with significant amounts of 2c. 1H NMR
showed spectroscopic properties identical to those of the platinum(II)
starting material. However, carrying out the same reaction in CD2Cl2
allowed for spectroscopic analysis of 6a. 1H NMR (CD2Cl2): δ ) 7.09
2
(s, 2H, C6H2), 4.25 (d, 2H, JHH ) 12.9 Hz, CH2N, lowfield part of
2
ABq), 3.40 (d, 2H, JHH ) 12.8 Hz, CH2N, highfield part of ABq),
3.04 (s, 6H, 3JPtH not resolved, NCH3Me), 2.72 (s, 6H, 3JPtH not resolved,
NMeCH3), 1.00 (s, 9H, CCH3), 0.69 (s, 9H, Me3Si), signal of Me2Si
not resolved due to overlap with the resonances of residual Me3SiOTf;
2
t
(acetone-d6): δ ) 7.12 (s, 2H, C6H2), 4.93 (d, 2H, JHH ) 13.2 Hz,
29Si NMR (CD2Cl2): δ ) 78.9 (Me3Si-arenium), 9.64 (Me2 BuSi-O).
2
t
CH2N, lowfield part of ABq), 3.62 (d, 2H, JHH ) 12.9 Hz, CH2N,
[PtCl(C6H2{Me3Si}-1-{CH2NMe2}2-2,6-OSiMe2 Bu-4)][CF3SO3]
3
highfield part of ABq), 3.46 (q, 2H, JHH ) 7.2 Hz, CCH2CH3), 3.11
(6b). To a solution of 2b (0.06 g, 0.1 mmol) in dry CD2Cl2 (0.7 mL)
3
3
(s, 6H, JPtH not resolved, NCH3Me), 2.77 (s, 6H, JPtH not resolved,
was added excess Me3SiOTf (0.1 mL, 0.5 mmol). Immediately, the
3
1
NMeCH3), 0.63 (t, 3H, JHH ) 7.4 Hz, CCH2CH3).
solution turned dark orange. H NMR (CD2Cl2): δ ) 7.05 (br s, 2H,
C6H2), 3.99 (br s, 4H, CH2N), 3.00 (br s, 6H, 3JPtH not resolved, NCH3-
Me), 2.77 (br s, 6H, 3JPtH not resolved, NMeCH3), 1.01 (s, 9H, CCH3),
0.69 (s, 9H, Me3Si), signal of Me2Si not resolved due to overlap with
the resonances of residual Me3SiOTf.
[PtCl(C6H2{CH2C6H5}-1-{CH2NMe2}2-2,6-OH-4)][BF4] (5a). To
a stirred solution of 2b (0.35 g, 0.69 mmol) in acetone (10 mL) was
poured BnCl (4 mL, 35 mmol) which caused a slow colorization to
orange. After 12 h, the formed precipitate was removed by filtration
and the filtrate evaporated in vacuo. The crude product was precipitated
from CHCl3/Et2O to yield 5a as a yellow solid (0.28 g, 67%). 1H NMR
(acetone-d6): δ ) 7.1-6.8 (m, 5H, C6H5), 6.96 (s, 2H, C6H2), 5.10 (d,
[PtI(C6H2{Me}-1-{CH2NMe2}2-2,6-O-4)] (7). Procedure A. A
solution of 3b (0.70 g, 1 mmol) in THF (5 mL) was treated with excess
NEt3 (1.4 mL, 10 mmol), which immediately caused a color change of
the solution from dark red to yellow. Toluene (20 mL) was added and
the suspension filtered. Evaporation of the filtrate gave 7 as a yellow
solid (0.53 g, 98%). Procedure B. Aqueous NaOH (4 M, 0.5 mL, 2
mmol) was added to a solution of 3c (0.71 g, 1 mmol) in THF (5 mL).
The reaction mixture became immediatlely yellow and was stirred for
30 min. After addition of NaOH (1 M, 15 mL) and toluene (20 mL),
the organic phase was separated and the aqueous layer extracted with
toluene (2 × 15 mL). The combined organic layers were dried over
Na2SO4 and filtered, and the solvent was removed under reduced
pressure. Slow precipitation from CH2Cl2/pentane afforded 7 as a
2
3
2H, JHH ) 13.2 Hz, JPtH ) 48.8 Hz, CH2N, lowfield part of ABq),
4.77 (s, 2H, 3JPtH not resolved, CCH2Ar), 3.71 (d, 2H, 2JHH ) 13.4 Hz,
3JPtH ) 39.7 Hz, CH2N, highfield part of ABq), 3.06 (s, 6H, JPtH
)
3
27.9 Hz, NCH3Me), 2.78 (s, 6H, 3JPtH ) 29.6 Hz, NMeCH3); 13C {1H}
NMR (acetone-d6): δ ) 173.1 (Cpara), 161.5 (Cortho), 129.2, 127.8, 127.5
(all C6H5), 118.7 (Cmeta), Cipso not observed, 68.9 (CH2N), 53.7 (NCH3-
Me), 51.9 (NMeCH3), 39.6 (CCH2Ar); Anal. Calcd for C19H26BClF4N2-
OPt (615.78): C, 37.06; H, 4.26; N, 4.55. Found: C, 38.14; H, 4.55;
N, 4.50.
[PtBr(C6H2{CH2C6H5}-1-{CH2NMe2}2-2,6-OH-4)][BF4] (5b). Ad-
dition of BnBr (3 mL, 25 mmol) to 2b (0.45 g, 0.89 mmol) in acetone
(10 mL) afforded a purple solution within 15 min. Analysis of this
intermediate 9: 1H NMR (acetone-d6): δ ) 7.15-6.90 (m, 5H, C6H5),
1
microcrystalline yellow solid (0.77 g, 71%). H NMR (CDCl3): δ )
6.07 (s, 2H, 4JPtH ) 16 Hz, C6H2), 4.22 (s, 2H, 2JHH ) 13.5 Hz, lowfield
3
part of ABq), 3.05 (s, 6H, JPtH ) 38.8 Hz, NMeCH3), 2.94 (s, 6H,
3JPtH ) 40.5 Hz, NCH3Me), 2.81 (s, 2H, 2JHH ) 13.2 Hz, 3JPtH ) 54.2
Hz, CH2N, highfield part of ABq), 1.54 (s, 3H, 3JPtH ) 51.2 Hz, CCH3);
13C {1H} NMR (CDCl3): δ ) 187.5 (Cpara), 163.0 (Cortho), 119.7 (3JPtC
) 24.3 Hz, Cmeta), 70.4 (CH2N), 56.2 (2JPtC ) 12 Hz, NMeCH3), 55.0
(2JPtC ) 21 Hz, NMeCH3), 49.1 (Cipso), 23.5 (2JPtC ) 97 Hz, CCH3);
17O NMR (THF): δ ) 450; Anal. Calcd for C13H21IN2OPt (543.31):
C, 28.42; H, 4.95; N, 5.10. Found: C, 28.55; H, 5.05; N, 5.13.
(C6H2{Bn}-4-{CH2NMe2}2-3,5-OH-1) (8b). A solution of 5b (15.4
mg, 23 µmol) in CH2Cl2 (5 mL) was vigorously stirred with an aqueous
solution of KCN (0.5 M, 6 mL, 3 mmol) for 4 h. Aqueous NaOH (2
M, 5 mL) was added, and the product was extracted with CH2Cl2 (3 ×
5 mL). The combined organic fractions were washed with brine (10
mL), dried over MgSO4, and evaporated to dryness to afford a yellowish
oil (6.5 mg, 94%).1H NMR (CDCl3): δ ) 7.22-6.95 (m, 5H, C6H5),
6.84 (s, 2H, C6H2), 4.24 (s, 2H, CCH2Ar), 3.25 (s, 4H, CH2N), 2.18 (s,
12H, NCH3); OH not observed; 13C {1H} NMR (CDCl3): δ ) 154.3,
141.1, 139.0, 129.8, 128.4, 127.9, 125.7, 116.3 (all Caryl), 61.6 (CH2N),
45.3 (NMe2), 32.4 (CH2).
2
6.80 (s, 2H, C6H2), 5.04 (d, 2H, JHH ) 13.2 Hz, CH2N, lowfield part
2
2
of ABq), 4.61 (s, 2H, JPtH ) 24 Hz, CCH2Ar), 3.58 (d, 2H, JHH
)
3
13.5 Hz, CH2N, highfield part of ABq), 3.11 (s, 6H, JPtH ) 32.6 Hz,
NCH3Me), 2.83 (s, 6H, JPtH ) 28.5 Hz, NMeCH3). Within 1 h, the
3
color of the reaction solution changed to orange, and after additional
1 h of stirring, the volatiles were removed by evaporation under reduced
pressure. The crude product was isolated by repetitive precipitation of
a CH2Cl2 solution with pentane and was finally recrystallized from
1
CHCl3/Et2O to yield 5b as an orange solid (0.48 g, 81%). H NMR
(acetone-d6): δ ) 7.1-6.8 (m, 5H, C6H5), 6.44 (s, 2H, C6H2), 5.11 (d,
2
3
2H, JHH ) 13.2 Hz, CH2N, lowfield part of ABq), 4.85 (s, 2H, JPtH
2
) 30 Hz, CCH2Ar), 3.72 (d, 2H, JHH ) 13.7 Hz, CH2N, highfield
part of ABq), 3.10 (s, 6H, JPtH not resolved, NCH3Me), 2.78 (s, 6H,
3
3JPtH ) 37.2 Hz, NMeCH3); 13C {1H} NMR (acetone-d6): δ ) 172.5
(Cpara), 157.5 (Cortho), 129.3, 129.1, 127.6, 127.5 (all C6H5), 118.4 (Cmeta),
79.8 (Cipso), 68.2 (CH2N), 55.0 (NCH3Me), 52.9 (NMeCH3), 39.3
(CCH2Ar); Anal. Calcd for C19H26BBtF4N2OPt (660.23): C, 34.57; H,
3.97; N, 4.24. Found: C, 34.72; H, 4.03; N, 4.29.
(C6H2{Me}-4-{CH2NMe2}2-3,5-OH-1) (8a). The procedure was
similar to that of 8b, starting from a solution of 3c (0.07 g, 0.1 mmol)
in CH2Cl2 (5 mL) and aqueous KCN (0.5 M, 6 mL, 3 mmol), giving
the title product as a yellowish oil (13 mg, 60%).
[PtBr(C6H2{CH2C6H5}-1-{CH2NMe2}2-2,6-OMe-4)][SO3CF3] (5c).
Addition of BnBr (1 mL, 8 mmol) to 2b (0.19 g, 0.36 mmol) in acetone
(4 mL) afforded a purple solution within 10 min, which subsequently
turned orange (1.5 h). The volatiles were removed in vacuo, and the
product was purified by repetitive crystallization from acetone/pentane
solution, which yielded 5c as orange crystals (0.16 g, 65%). 1H NMR
(acetone-d6): δ ) 7.29 (s, 2H, C6H2), 7.15-7.12 (m, 3H, C6H5), 6.89-
6.85 (m, 2H, C6H5), 5.17 (d, 2H, 2JHH ) 13.3 Hz, CH2N, lowfield part
of ABq), 4.97 (s, 2H, 3JPtH not resolved, CCH2Ar), 4.21 (s, 3H, OMe),
1H NMR (CDCl3): δ ) 6.15 (s, 2H, C6H2), 3.50 (s, 4H, CH2N),
2.22 (s, 12H, NCH3), 1.72 (s, 3H, ArCH3); OH not observed.
Reaction of [Pt(C6H2{CH2NMe2}2-2,6-OH-4)(OH2)][CF3SO3] (2a)
with HCl. A solution of 2a (40 mg, 0.07 mmol) in acetone-d6 (2 mL)
was treated with freshly prepared gaseous HCl. The color of the mixture
turned orange, and a white precipitate formed, which was removed by
filtration. Analysis of the orange solution: 1H NMR (acetone-d6): δ
2
3.84 (d, 2H, JHH ) 13.4 Hz, CH2N, highfield part of ABq), 3.12 (s,
6H, 3JPtH ) 29.4 Hz, NCH3Me), 2.79 (s, 6H, 3JPtH ) 24.2 Hz, NMeCH3);
13C {1H} NMR (acetone-d6): δ ) 171.1 (Cpara), 154.2 (Cortho), 140.5,
129.5, 127.7, 127.6 (all C6H5), 117.1 (Cmeta), 83.4 (Cipso), 69.3 (CH2N),
59.0 (OMe), 55.2 (NCH3Me), 53.0 (NMeCH3), 39.0 (CCH2Ar).
[PtI(C6H2{Me3Si}-1-{CH2NMe2}2-2,6-OSiMe2tBu-4)][CF3SO3] (6a).
3
) 5.92 (s, 2H, C6H2), 4.41 (s, 2H, JPtH ) 30.3 Hz, CH2N), 4.00 (s,
3
3
2H, JPtH ) 45.9 Hz, CH2N), 3.02 (s, 6H, JPtH ) 29.5 Hz, NMe2),
3.00 (s, 6H, 3JPtH ) 38.7 Hz, NMe2). Evaporation of the orange filtrate
afforded a dark oily residue. The H NMR data of this product are
1
t
identical with those of the starting material 2a.
To a solution of [PtI(C6H2{CH2NMe2}2-2,6-OSiMe2 Bu-4)] (0.11 g, 0.2
mmol) in dry CH2Cl2 (3 mL) was added excess Me3SiOTf (0.8 mL, 4
mmol). Immediately, the solution turned dark red. When this solution
was layered with dry pentane, a white crystalline solid was obtained
together with some decomposition products. The crystalline material
Structure Determination and Refinement of 3c and 5c. X-ray
data were collected on an Enraf-Nonius CAD4-T diffractometer with
rotating anode (Mo KR radiation, λ ) 0.71073 Å). Crystal data and
details on data collection and refinement are given in Table 3. The