Date of Graduation
Eberly College of Arts and Sciences
Kung K. Wang.
Treatment of alkenyldicyclohexylboranes with 1-lithio-5-butyl-3,4-nonadien-1-yne, derived from 5-butyl-3,4-nonadien-1-yne, followed by trimethyltin chloride and acetic acid furnished the corresponding o-isotoluenes in a single operation. The reaction proceeded through an initial formation of (Z)-diene-allenes, which underwent facile eletrocyclizations to produce o-isotoluenes.;Treatment of allenyldicyclohexylborane with 1-lithio-5,5-pentamethylene-3,4-pentadien-1-yne produced the organoborate complex, which on further treatment with trimethyltin chloride furnished a (Z)-1,2,4,6,7-octapentaene (enediallene) derivative in situ. The subsequent electrocyclic reaction then generated the corresponding o-quinodimethane attached with a dicyclohexylboryl group and a trimethyltin group. The resulting o-quinodimethane then underwent a [1,5]-sigmatropic hydrogen shift, and on subsequent oxidative workup and protonation gave the 4-(1-cyclohexenyl)-3-methylphenol (51%). The presence of a boron group and a tin group in the benzene ring of a reaction intermediate also provides handles to allow their transformations to an allyl substituent and an iodo substituent to produce a tetrasubstituted benzene ring (30%) in a single operation. Attempts to capture the o-quinodimethane intermediate with a carbon--carbon double bond intramolecularly afforded a tricyclic phenol in low yield (6%). A number of other o-quinodimethanes were also generated by using different combinations of organoboranes and 1-lithio-1-alkynes.;6H-Indolo[2,3-b]quinolines were synthesized from N-[2-(1-alkynyl)- phenyl]-N'-phenylcarbodiimides via a thermally-induced biradical-forming reaction. The Pd-catalyzed cross-coupling reaction between methyl 2-iodobenzoate and 1-alkynes furnished methyl 2-(1-alkynyl)benzoates, which were hydrolyzed to afford the corresponding benzoic acids. Treatment of the benzoic acids with diphenyl phosphorazidate produced the 2-(1-alkynyl)phenyl isocyanates. The subsequent aza-Wittig reactions with the iminophosphorane, derived from aniline and Ph3P·Br2 then gave the benzoenynyl carbodiimides. Thermolysis of the benzoenynyl carbodiimides in refluxing p-xylene at 138°C produced the corresponding 6H-indolo[2,3-b]quinolines. Similarly, thermolysis of the carbodiimides having two benzoenynyl carbodiimide moieties produced compounds having two indoloquinoline units connected at the 11 and the 11' positions with either a three-carbon or a five-carbon tether. By using 1,4-phenylene diisocyanate for the aza-Wittig reaction with two equiv of the iminophosphorane followed by thermolysis furnished a compound (66%) having two indoloquinoline units incorporated in the seven fused rings.;The synthetic pathway to the 6H-indolo[2,3- b]quinolines was successfully adopted for preparation of the 5-aza anologues of ellipticine, a naturally occuring alkaloid having potent anti-cancer properties. This approach, which constructs the B and the C rings in one step, is an efficient route in producing the aza analogues of the ellipticine family of antitumor alkaloids.
Zhang, Quan, "Synthesis of o-isotoluenes, o-quinodimethanes, and benzoenynyl carbodiimides and their cyclizations to polycyclic and heterocyclic compounds" (1999). Graduate Theses, Dissertations, and Problem Reports. 1050.