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Large Scale Synthesis and Derivatization of Corannulene: The Smallest BuckybowlBachawala, Praveen 09 December 2006 (has links)
The major part of my thesis work includes large scale production of corannulene, C20H10, a bowl-shaped Polycyclic Aromatic Hydrocarbon. Over the road towards corannulene via tetramethylfluoranthene, we improved several steps of the existing multistep procedure. These improvements include: -Nucleophilic displacement of chloride in 2,7-dimethyl-1-chloromethyl- naphthalene with cyanide gave an excellent yield of 2,7-dimethyl-1-naphthalene- acetonitrile when performed in acetonitrile instead of DMSO or acetone/water. -Oxidation of 3,8-dimethyl-1-acenaphthenone to 3,8-dimethylacenaphthaquinone was successfully achieved with HBr/DMSO instead of selenium dioxide, which usually requires tedious work up. -Overall yield of 3,8-dimethylacenaphth- aquinone was greatly improved in comparison with the previous reports. -Palladium catalyzed large scale debromination of tetrabromocorannulene was accomplished within thirty minutes of brief reflux, in contrast to the original Zn/KI method which took weeks for completion. Alternative palladium catalyzed ring closure methods where tested for synthesis of 1,6,7,10-tetramethylfluroanthene (25), a key intermediate in corannulene production. A structurally similar system, 7,10-dimethylfluoranthene was synthesized by this new approach in low yield. Unfortunately, we did not succeed in the synthesis of 25 using similar methodology, since all our attempts to produce the prerequisite 2,7-dimethyl-1-naphthylboronic acid failed. Elaboration of the corannulene core by coupling tetrabromocorannulene with p-methoxyphenylboronic acid and p-methoxycarbonylphenylboronic acid under Suzuki conditions resulted in formation of two vital intermediates which can be used to build capsules with corannulene caps.
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