Synthesis and characterization of N-phenyl pyrrole anchored to Fischer carbene complex through ring closing metathesis oxidative aromatization and various aryl substituted Fischer carbene complexes

Abstract

Ring closing metathesis of pentacarbonyl[(ethoxy)(N,N-diallyl anilyl)carbene]tungsten(0) complex, [(CO)5Wdouble bondC(OCH2CH3)C6H4N(CH2CHdouble bondCH2)2], 1 leads to the formation of pentacarbonyl[(ethoxy)(N-phenyl 2,5-dihydro pyrrolyl)carbene]tungsten(0) complex, [(CO)5Wdouble bondC(OCH2CH3)C6H4N (CH2CHdouble bondCH2)2], 2 in good yield. Further, complex 2 undergoes oxidative aromatization to afford N-phenyl pyrrole anchored to alkoxy carbene, 3. In addition, a number of aryl substituted carbene complexes [(CO)5Wdouble bondC(OCH2CH3)C6H4R], 4–7 (4: R = OCH2CH3; 5: R = OCH2CHdouble bondCH2; 6: R = OCHdouble bondCHCH2CH2CH2CH2CH3; 7: OC6H5Br) have been synthesized from the reaction of 1-(allyloxy)-4-bromobenzene with W(CO)6 in presence of various concentration of n-BuLi and Meerwein's salt. All the complexes have been isolated in moderate to good yields and have been characterized by 1H NMR, 13C NMR, IR, UV–vis spectroscopic techniques and the solid state structures of 1, 2 and 4 have been unequivocally established by X-ray diffraction analysis.