Carbon-Carbon Bond Formation Via o-Lithiointermediates

• Main Author: Raymer, Julia
• Format: Others
• Published: TopSCHOLAR® 2004
• Subjects: Chemistry
• Online Access: http://digitalcommons.wku.edu/theses/512; http://digitalcommons.wku.edu/cgi/viewcontent.cgi?article=1515&context=theses

The process of C-C bond formation via Directed ort/zo-Metalation (DoM) consists of two separate steps. Utilizing fractional equivalents of TMEDA in hydrocarbon solvents at 60°C, o-lithiation of anisole and dimethylaniline can be effected in >95% yields. The first step in the DoM process involves preparation of solid samples of these o-lithiointermediates. Completing the sequence, the second step concerns formation of a new arene-derivative bond at the reactive site. For this thesis the arene-derivative bond formed is to carbon. Various carbon electrophiles have been studied using different solvent systems, and results reveal a possible disconnect between the reaction conditions for the formation of the o-lithiointermediate and its subsequent derivatization. Simple additions to several ketones produce a wide variety of results when solvated in cyclohexane, THF, glyme, or diglyme. The use of CsF has provided questionable assistance to certain reaction conditions. Product distribution variations were seen in reactions of the o-lithioarenes with tetramethylurea and diethylcarbonate. Unsymmetric biphenyl derivatives are also produced via reaction of a benzyne intermediate with the olithioarenes. Some useful Buchwald catalysts can be made by this procedure. It is the use of pure o-lithioarenes that permits control of the solvent in various derivatization steps, therefore permitting further understanding and manipulation of the reaction conditions.