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

Ring closing metathesis of pentacarbonyl[(ethoxy)(N,N-diallyl anilyl)carbene]tungsten(0) complex, [(CO)5Wdouble bond; length as m-dashC(OCH2CH3)C6H4N(CH2CHdouble bond; length as m-dashCH2)2], 1 leads to the formation of pentacarbonyl[(ethoxy)(N-phenyl 2,5-dihydro pyrrolyl)carbene]tungsten(0) complex, [(CO)5Wdouble bond; length as m-dashC(OCH2CH3)C6H4N (CH2CHdouble bond; length as m-dashCH2)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 bond; length as m-dashC(OCH2CH3)C6H4R], 4–7 (4: R = OCH2CH3; 5: R = OCH2CHdouble bond; length as m-dashCH2; 6: R = OCHdouble bond; length as m-dashCHCH2CH2CH2CH2CH3; 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 Meerweinʹs 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.