Metal-Mediated Transformations of Cyclooctatetraene to Novel Methylene-Bridged, Bicyclic Compounds
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- 作者：Sonja Schö ; rshusen ; Jü ; rgen Heck
- 刊名：Organometallics
- 出版年：2007
- 出版时间：October 22, 2007
- 年：2007
- 卷：26
- 期：22
- 页码：5386 - 5394
- 全文大小：437K
- 年卷期：v.26,no.22(October 22, 2007)
- ISSN：1520-6041
文摘
The nucleophilic addition of Nu1 to [(5-Cp)Fe(6-cot)]PF6 (1PF6) (cot = cyclooctatetraene) exclusivelyyields the neutral complex [(5-Cp)Fe(1,2,3,4,5--C8H8-Nu1)] (2) [Nu1 = C(CO2Et)2CH2CHCH2 (2a),C(CO2Et)2(CH2)2CHCH2 (2b), C(CO2Et)2(CH2)3CHCH2 (2c)], with the nucleophiles linked to the cyclo-C8 ligand solely and stereoselectively in exo position with respect to the metal center. The protonationof the neutral complexes 2a-c by addition of HBF4 reveals the new ionic product [(5-Cp)Fe(6-C8H9-Nu1)]BF4 (3BF4) with a 1,2,3,4,5,6- coordination mode of the cyclo-C8 ligand. The cationic complexes3a-c are suitable for a second nucleophilic addition affording the exo-6,8-disubstituted cyclooctadienylcomplex [(5-Cp)Fe(1,2,3,4,5--C8H9-6-Nu1-8-Nu2)] (4) [Nu1/Nu2 = C(CO2Et)2CH2CHCH2/C(CO2Et)2CH2CHCH2 (4a), C(CO2Et)2CH2CHCH2/C(CO2Et)2(CH2)2CHCH2 (4b), C(CO2Et)2CH2CHCH2/C(CO2Et)2(CH2)3CHCH2 (4c), C(CO2Et)2(CH2)2CHCH2/C(CO2Et)2(CH2)2CHCH2 (4d), C(CO2Et)2(CH2)2CHCH2/C(CO2Et)2(CH2)3CHCH2 (4e), C(CO2Et)2(CH2)3CHCH2/C(CO2Et)2(CH2)3CHCH2 (4f)]. The cyclo-C8 ligandcan be cleaved as cis-5,7-disubstituted cycloocta-1,3-diene (5) by protonation of the complexes 4a-fwith CF3CO2H in acetonitrile: Nu1/Nu2 = C(CO2Et)2CH2CHCH2/C(CO2Et)2CH2CHCH2 (5a), C(CO2Et)2CH2CHCH2/C(CO2Et)2(CH2)2CHCH2 (5b), C(CO2Et)2CH2CHCH2/C(CO2Et)2(CH2)3CHCH2 (5c),C(CO2Et)2(CH2)2CHCH2/C(CO2Et)2(CH2)2CHCH2 (5d), C(CO2Et)2(CH2)2CHCH2/C(CO2Et)2(CH2)3CHCH2(5e), C(CO2Et)2(CH2)3CHCH2/C(CO2Et)2(CH2)3CHCH2 (5f). In an attempt to construct fused bicyclicring systems with annelated 9- to 13-membered cycles employing the ring-closing metathesis (RCM), anovel ring opening-ring closing metathesis reaction was encountered to yield new methylene-bridged,bicyclic systems (7).