Dilithiation of aromatic hydrocarbons.

The polycyclic aromatic hydrocarbons triphenylene, chrysene and phenanthrene have been dilithiated using butyllithium in N,N,N$\sp\prime$N$\sp\prime$-tetramethylethylenediamine (TMEDA) and hexane. Subsequent treatment with electrophiles allows preparation of derivatives functionalized in the bay region. In this manner reaction of 1,12-dilithiotriphenylene with iodine affords 1,12-diiodotriphenylene, for which the molecular structure was determined by X-ray crystallography. This diiodide shows gross distortion from planarity due to steric crowding of the iodine atoms. The reaction of 4,5-dilithiochrysene with sulfur dichloride gave chryseno (4,5-bcd) thiophene. This thiophene which is an isoester of benzo (a) pyrene has been subjected to biological testing and shows potentially mutagenic properties. Reaction of (Z)-2-lithiostyrene with t-butyllithium and TMEDA affords (Z)-2-lithio-ortho-lithiostyrene, a 1,4-dilithio compound. Subsequent reaction with electrophiles allows an easy preparation of indole analogs. The reaction with phenylarsenic dichloride affords benzo (a) arsole. Reaction of Naphthalene with n-butyllithium and TMEDA in hexane affords 1,8-dilithionaphthalene, which on subsequent reaction with elemental sulfur gave naphtho (1,8-cd) -1,2-dithiole. 9-Lithiophenanthrene reacts with n-butyllithium and TMEDA to afford 1,10-dilithiophenanthrene, a peri-dilithiated phenanthrene. The reaction of this dilithio compound with elemental sulfur gave phenanthro (1,10-cd) -1,2-dithiole. 1-Lithio-2-phenylnaphthalene gave bay-dilithiation in preference to peri-dilithiation indicating that 1,4-dilithiation is favored over 1,3-dilithiation. TMEDA adducts of 1,12-dilithiotriphenylele, (Z)-2-lithio-ortho-lithiostyrene and 1,4-bis(trimethylsilyl)-1,4-bis(lithio)-2,3-dimethyl-$ 1,3$-butadiene have been characterized by NMR spectroscopy. X-ray structure of 1,4-bis(trimethylsilyl)-1,4-bis(lithio$\cdot $TMEDA)-2,3-dimethyl-1,3-butadiene has been obtained. Each lithium atom bridges C(1) and C(4) forming a symmetrical four-membered ring, which is in accordance with the geometry of the parent compound (without TMEDA) predicted by theoretical calculations.PhDChemistryUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/103667/1/9332163.pdfDescription of 9332163.pdf : Restricted to UM users only