Alkyllithiums chelating ether groups

B. Mixed Complexes between Alkyllithiums and Chiral Lithium Amides with Chelating Ether Groups... 

The mechanism of organolithium addition to naphthyl oxazolines is believed to occur via initial complexation of the alkyllithium reagent to the oxazoline nitrogen atom and the methyl ether to form chelated intermediate 17. Addition of the alkyl group to the arena 7t-system affords azaenolate 18, which undergoes reaction with an electrophile on the opposite face of the alkyl group to provide the observed product 4. The chelating methyl... 

The nucleophilic addition of -alkyllithiums to a,a -disubstituted [l,8]naphthyridines has been achieved in a nonpolar diethyl ether-hexane mixed solvent (Scheme 5) note that when performed in a more polar solvent such as tetrahydrofuran (THF), the alkyllithium acts as a base <2005S1397>. A group capable of five-membered ring chelation at the a-position gave excellent selectivity for that site over an a-position without a chelating group. 

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