Frustrated -Chloride Elimination. Selective Arene Alkylation by 
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- 作者：Aswini K. Dash ; Tryg R. Jensen ; Charlotte L. Stern ; and Tobin J. Marks
- 刊名：Journal of the American Chemical Society
- 出版年：2004
- 出版时间：October 6, 2004
- 年：2004
- 卷：126
- 期：39
- 页码：12528 - 12540
- 全文大小：291K
- 年卷期：v.126,no.39(October 6, 2004)
- ISSN：1520-5126
文摘
Single-site polymerization catalysts generated in situ via activation of Cp*MMe3 (Cp* = C5Me5;M = Ti, Zr), (CGC)MMe2 (CGC = C5Me4SiMe2NBut; M = Ti, Zr), and Cp2ZrMe2 with Ph3C+B(C6F5)4- catalyzealkylation of aromatic molecules (benzene, toluene) with 
BORDER=0>-chloronorbornene at room temperature, toregioselectively afford the 1:1 addition products exo-1-chloro-2-arylnorbornane (aryl = C6H5 (1a), C6H4CH3 (1b)) in good yields. Analogous deuterium-labeled products exo-1-chloro-2-aryl-dn-norbornane-7-d1(aryl-dn = C6D5 (1a-d6), C6D4CD3 (1b-d8)) are obtained via catalytic arylation of -chloronorbornene ineither benzene-d6 or toluene-d8. Isolated ion-pair complexes such as (CGC)ZrMe(toluene)+B(C6F5)4- andCp*2ThMe+B(C6F5)4- also catalyze the reaction of -chloronorbornene in toluene-d8 to give 1b-d8 in goodyields, respectively. Small quantities of the corresponding bis(1-chloronorbornyl)aromatics 2 are also obtainedfrom preparative-scale reactions. These reactions exhibit turnover frequencies exceeding 120 h-1 (for theCp*TiMe3/Ph3C+B(C6F5)4--catalyzed system), and chlorine-free products are not observed. Compounds 1and 2 were characterized by 1H, 2H, 13C, and 2D NMR, GC-MS, and elemental analysis. The aryl groupexo-stereochemistry in 1a and 1b is established using 1H-1H COSY, 1H-13C HMBC, and 1H-1H NOESYNMR, 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 involvingparticipitation of the metal electrophiles in the catalytic cycle.
BORDER=0>-chloronorbornene at room temperature, toregioselectively afford the 1:1 addition products exo-1-chloro-2-arylnorbornane (aryl = C6H5 (1a), C6H4CH3 (1b)) in good yields. Analogous deuterium-labeled products exo-1-chloro-2-aryl-dn-norbornane-7-d1(aryl-dn = C6D5 (1a-d6), C6D4CD3 (1b-d8)) are obtained via catalytic arylation of -chloronorbornene ineither benzene-d6 or toluene-d8. Isolated ion-pair complexes such as (CGC)ZrMe(toluene)+B(C6F5)4- andCp*2ThMe+B(C6F5)4- also catalyze the reaction of -chloronorbornene in toluene-d8 to give 1b-d8 in goodyields, respectively. Small quantities of the corresponding bis(1-chloronorbornyl)aromatics 2 are also obtainedfrom preparative-scale reactions. These reactions exhibit turnover frequencies exceeding 120 h-1 (for theCp*TiMe3/Ph3C+B(C6F5)4--catalyzed system), and chlorine-free products are not observed. Compounds 1and 2 were characterized by 1H, 2H, 13C, and 2D NMR, GC-MS, and elemental analysis. The aryl groupexo-stereochemistry in 1a and 1b is established using 1H-1H COSY, 1H-13C HMBC, and 1H-1H NOESYNMR, 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 involvingparticipitation of the metal electrophiles in the catalytic cycle.