Organolithium reagents complexes with ethers

This complex should be used when the organolithium is in solution in a hydrocarbon solvent. For organolithium reagents prepared in ether (see Note 4), the same complex may be used or, more conveniently, copper iodide (Cull can be used. The Cul purchased from Prolabo or Merck 4 Company, Inc. may be used directly. Other commercial sources of Cul (Fluka, Aldrich Chemical Company, Inc., Alfa Products, Morton/Thiokol, Inc.) furnish a salt which affords better results when purified. 1 mol of Cul is stirred for 12 hr with 500 ml of anhydrous tetrahydrofuran, then filtered on a sintered glass funnel ( 3), washed twice with 50 ml of anhydrous tetrahydrofuran, once with 50 ml of anhydrous ether and finally dried under reduced pressure (0.1 imO for 4 hr. 

The equatorial selectivity observed with organolithium reagents is enhanced in diethyl ether as the reaction solvent by the addition of lithium perchlorate (Table l)12. I3C-NMR studies47 indicate that the formation of a complex between lithium perchlorate and the carbonyl group, which also leads to a dramatic enhancement of the rate of the addition reaction, accounts for the increased diastereoselectivity. 

Nucleophilic addition to this complex salt occurs mostly at the 5-position. Addition of cyanides affords also a minor amount of an T), n -structure by addition to the 2-position. The tricarbonyl(Ti -3-methoxycyclohexa-2,4-dien-l-yl)iron cation reacts with a variety of nucleophiles, comprising organolithium reagents, ketones, silyl enol ethers, and allylsilanes, to give after oxidative demetalation 5-substituted cyclohex-2-enones (Scheme 4-175). 

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... 

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