Tungsten reagents

Fe(CO)5,29B TiCI3-LiA H4,2W FeCI -BuLi,300 the tungsten reagents mentioned in 7-21,265 and Nal-NaOAc-Zn-AcOH.301 The last-mentioned method is actually a variation of 7-31, since iodohydrins are intermediates. Some of these methods give syn elimination. 

Yields are highest in the case of aromatic aldehydes and ketones application of the reaction to butanone-2, for example, gives only a 10 %, yield of olefin. Reagent I is more effective than the other tungsten reagents (II-VI) for the coupling reaction. 

The new tungsten reagents (1-Vl) are also effective for deoxygenation of epoxides to the parent olefin. Reagents V and Vl are the cheapest and most convenient reagents for this purpose however, reagents l-lll serve well for small- and medium-scale reactions. In a typical experiment WCl (0.15 mole) is added to THF (420 ml.) cooled to —62° n-butyllithium (0..30 mole) is added slowly at this temperature. The mixture is allowed to warm slowly to room temperature. The oxide (0.08 mole) is added. A rapid exothermic reduction takes place. After 0.5 hr. the product is poured into an aqueous solution containing sodium tartrate and NaOH. and the olefin extracted with hexane. 

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