| Abstract
| - A regioselective carbolithiation of o-amino-(E)-stilbenes has been achieved with a series of alkyllithiumswhen THF is employed as the reaction solvent. The use of other solvents, such as diethyl ether orhydrocarbons, leads to a pronounced loss in regioselectivity. Moreover, high levels of diastereoselectivityhave been obtained following reaction of the lithiated intermediate in THF with different electrophilessuch as MeOD, CO2, and Bu3SnCl. It was shown that diastereoselectivity was influenced by the ortho-amino substituent and the alkyllithium utilized for carbolithiation with N-Boc substituent and t-BuLiproving optimal. In the case of carbolithiated intermediate 3a, obtained from the reaction of N-Bocsubstituted stilbene with t-BuLi, 1H and 13C NMR analysis revealed predominantly one diastereoisomerwhich was stable at room temperature. Application of the carbolithiation/electrophile reaction methodologyto the synthesis of six-membered quinoline ring systems is demonstrated with substituted 3,4-dihydroquinolin-2-ones, 1,2,3,4-tetrahydroquinolines, 1,4-dihydroquinolines, and quinolines all preparedby a common cascade route.
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