Abstract
Single-site polymerization catalysts generated in situ via activation of Cp*MMe3 (Cp* = C5Me5; M = Ti, Zr), (CGC)MMe2 (CGC = C5Me4SiMe2NBu t; M = Ti, Zr), and Cp2ZrMe2 with Ph 3C+B(C6F5)4 - catalyze alkylation of aromatic molecules (benzene, toluene) with α-chloronorbornene at room temperature, to regioselectively afford the 1:1 addition products exo-1-chloro-2-arylnorbornane (aryl = C6H 5 (1a), C6H4-CH3 (1b)) in good yields. Analogous deuterium-labeled products exo-1-chloro-2-aryl-d n-norbornane-7-d1 (aryl-dn = C 6D5 (1a-d6), C6D4CD 3 (1b-d8)) are obtained via catalytic arylation of α-chloronorbornene in either benzene-d6 or toluene-d 8. Isolated ion-pair complexes such as (CGC)ZrMe(toluene) +B(C6F5)4 - and Cp*2ThMe+B(C6F5) 4 - also catalyze the reaction of α-chloronorbornene in toluene-d8 to give 1b-d8 in good yields, respectively. Small quantities of the corresponding bis(1-chloronorbornyl)aromatics 2 are also obtained from preparative-scale reactions. These reactions exhibit turnover frequencies exceeding 120 h-1 (for the Cp*TiMe 3/Ph3C+B(C6F5) 4 --catalyzed system), and chlorine-free products are not observed. Compounds 1 and 2 were characterized by 1H, 2H, 13C, and 2D NMR, GC-MS, and elemental analysis. The aryl group exo-stereochemistry in 1a and 1b is established using 1H- 1H COSY, 1H-13C HMBC, and 1H- 1H NOESY NMR, and is further corroborated by X-ray analysis of the product 1,4-bis(exo-1-chloro-2-norbornyl)benzene (2a). Control experiments and reactivity studies on each component step suggest a mechanism involving participitation of the metal electrophiles in the catalytic cycle.
| Original language | English |
|---|---|
| Pages (from-to) | 12528-12540 |
| Number of pages | 13 |
| Journal | Journal of the American Chemical Society |
| Volume | 126 |
| Issue number | 39 |
| DOIs | |
| Publication status | Published - Oct 6 2004 |
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Frustrated β-chloride elimination. Selective arene alkylation by α-chloronorbornene catalyzed by electrophilic metallocenium ion pairs. / Dash, Aswini K.; Jensen, Tryg R.; Stern, Charlotte L.; Marks, Tobin J.
In: Journal of the American Chemical Society, Vol. 126, No. 39, 06.10.2004, p. 12528-12540.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Frustrated β-chloride elimination. Selective arene alkylation by α-chloronorbornene catalyzed by electrophilic metallocenium ion pairs
AU - Dash, Aswini K.
AU - Jensen, Tryg R.
AU - Stern, Charlotte L.
AU - Marks, Tobin J
PY - 2004/10/6
Y1 - 2004/10/6
N2 - Single-site polymerization catalysts generated in situ via activation of Cp*MMe3 (Cp* = C5Me5; M = Ti, Zr), (CGC)MMe2 (CGC = C5Me4SiMe2NBu t; M = Ti, Zr), and Cp2ZrMe2 with Ph 3C+B(C6F5)4 - catalyze alkylation of aromatic molecules (benzene, toluene) with α-chloronorbornene at room temperature, to regioselectively afford the 1:1 addition products exo-1-chloro-2-arylnorbornane (aryl = C6H 5 (1a), C6H4-CH3 (1b)) in good yields. Analogous deuterium-labeled products exo-1-chloro-2-aryl-d n-norbornane-7-d1 (aryl-dn = C 6D5 (1a-d6), C6D4CD 3 (1b-d8)) are obtained via catalytic arylation of α-chloronorbornene in either benzene-d6 or toluene-d 8. Isolated ion-pair complexes such as (CGC)ZrMe(toluene) +B(C6F5)4 - and Cp*2ThMe+B(C6F5) 4 - also catalyze the reaction of α-chloronorbornene in toluene-d8 to give 1b-d8 in good yields, respectively. Small quantities of the corresponding bis(1-chloronorbornyl)aromatics 2 are also obtained from preparative-scale reactions. These reactions exhibit turnover frequencies exceeding 120 h-1 (for the Cp*TiMe 3/Ph3C+B(C6F5) 4 --catalyzed system), and chlorine-free products are not observed. Compounds 1 and 2 were characterized by 1H, 2H, 13C, and 2D NMR, GC-MS, and elemental analysis. The aryl group exo-stereochemistry in 1a and 1b is established using 1H- 1H COSY, 1H-13C HMBC, and 1H- 1H NOESY NMR, and is further corroborated by X-ray analysis of the product 1,4-bis(exo-1-chloro-2-norbornyl)benzene (2a). Control experiments and reactivity studies on each component step suggest a mechanism involving participitation of the metal electrophiles in the catalytic cycle.
AB - Single-site polymerization catalysts generated in situ via activation of Cp*MMe3 (Cp* = C5Me5; M = Ti, Zr), (CGC)MMe2 (CGC = C5Me4SiMe2NBu t; M = Ti, Zr), and Cp2ZrMe2 with Ph 3C+B(C6F5)4 - catalyze alkylation of aromatic molecules (benzene, toluene) with α-chloronorbornene at room temperature, to regioselectively afford the 1:1 addition products exo-1-chloro-2-arylnorbornane (aryl = C6H 5 (1a), C6H4-CH3 (1b)) in good yields. Analogous deuterium-labeled products exo-1-chloro-2-aryl-d n-norbornane-7-d1 (aryl-dn = C 6D5 (1a-d6), C6D4CD 3 (1b-d8)) are obtained via catalytic arylation of α-chloronorbornene in either benzene-d6 or toluene-d 8. Isolated ion-pair complexes such as (CGC)ZrMe(toluene) +B(C6F5)4 - and Cp*2ThMe+B(C6F5) 4 - also catalyze the reaction of α-chloronorbornene in toluene-d8 to give 1b-d8 in good yields, respectively. Small quantities of the corresponding bis(1-chloronorbornyl)aromatics 2 are also obtained from preparative-scale reactions. These reactions exhibit turnover frequencies exceeding 120 h-1 (for the Cp*TiMe 3/Ph3C+B(C6F5) 4 --catalyzed system), and chlorine-free products are not observed. Compounds 1 and 2 were characterized by 1H, 2H, 13C, and 2D NMR, GC-MS, and elemental analysis. The aryl group exo-stereochemistry in 1a and 1b is established using 1H- 1H COSY, 1H-13C HMBC, and 1H- 1H NOESY NMR, and is further corroborated by X-ray analysis of the product 1,4-bis(exo-1-chloro-2-norbornyl)benzene (2a). Control experiments and reactivity studies on each component step suggest a mechanism involving participitation of the metal electrophiles in the catalytic cycle.
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U2 - 10.1021/ja047828w
DO - 10.1021/ja047828w
M3 - Article
VL - 126
SP - 12528
EP - 12540
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 39
ER -