| The first half of the thesis reports on a study of the reactions of {dollar}alpha,beta,gamma,delta{dollar}-unsaturated alkynes with Fischer carbene complexes. Depending on the nature of the unsaturations in the dienyne, metathesis and subsequent CO insertion is followed by six-electron cyclization either onto the carbene portion of the molecule (Dotz benzannulation) or onto the dienyne portion ("reverse" benzannulation). For dienynes in which the alkyne is silylated and the central unsaturation is not part of an aromatic ring, "reverse" cyclization occurs. For example, 1-(2{dollar}spprime{dollar}-carbomethoxyethenyl)-2-(trimethylsilylacetylenyl)cyclohexene reacted with ((phenyl)methoxymethylene) pentacarbonylchromium to yield 1-(2-methoxy-2-phenyl-1-trimethylsilyl-ethenyl)-3-carbomethoxy-5,6,7,8-tetrahydro-2-naphthol. Dienynes with terminal alkynes and aromatic rings providing the central unsaturation predominantly yielded Dotz cyclization products, while the silylated analogs yielded cyclopentadienones as the major products.; The second half of the thesis discusses development of two organometallic routes that provide access to indolocarbazole derivatives.; It was demonstrated that 3-iodobiindolyl derivatives undergo a palladium catalyzed cyclization reaction with alkynes to yield substituted indolocarbazoles. Unsymetrically N,N-disubstituted biindolyls reacted with some degree of regioselectivity, with the major isomer determined by the sterics of the alkyne. For example, 3-iodo-1-benzyl-2-(1-methylindol-2-yl)indole reacted with ethyl phenylpropiolate in the presence of Pd (0) to yield 11-benzyl-6-ethoxycarbonyl-12-methyl-5-phenyl-11,12-dihydroindolo (2,3-a) carbazole plus a regioisomer in a ratio of 4:1.; Fischer carbene complexes were also employed as precursors to indolocarbazoles. Photocyclization of 3- ((1-methyl-2-(1-methylindol-2-yl)indol-3-yl)methoxymethylene) pentacarbonylchromium yielded 6-hydroxyl-5-methoxy-11,12-dimethyl-11,12-dihydroindolo (2,3-a) carbazole. Addition of tert-butyl isonitrile to the same carbene complex followed by thermal cyclization of the resulting ketenimine yielded 6-t-butylamino-5-methoxy-11,12-dimethyl-11,12-dihydroindolo (2,3-a) carbazole. |
