Semester

Spring

Date of Graduation

1999

Document Type

Dissertation

Degree Type

PhD

College

Eberly College of Arts and Sciences

Department

Chemistry

Committee Chair

Kung K. Wang.

Abstract

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.

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