THE GILMAN REAGENT

The sense of the asymmetric induction at the /J-carbon of 10 is opposite to that of 7, indicating that 10 reacts with the Gilman reagents in a conformation where the carbonyl is s-trans to the a,(i double bond to avoid steric repulsion of the a-substituent and the camphor residue. 

The Corey—Posner, Whitesides—House reaction involves the coupling of a hthium dialkyl-cuprate (called a Gilman reagent) with an alkyl, alkenyl, or aryl halide. The alkyl group of the lithium dialkylcuprate reagent may be primary, secondary, or tertiary. However, the halide with which the Gilman reagent couples must be a primary or cychc secondary alkyl halide if it is not alkenyl or aryl. 

Show how 1-bromobutane could be converted to the Gilman reagent lithium dibutylcu-prate, and how you could use it to synthesize each of the following compounds. 

The Gilman reagent has been used in the industrial synthesis of muscalure, the sex attractant of the common house-fly. Muscalure is added to fly bait that also contains an insecticide. When the fly eats the bait, the attraction is fatal. 

The Gilman reagents also undergo coupling reactions with aryl halides. For example, bromobertzene reacts with lithium dimethylcuprate to give toluene. 

Some reactions of the Gilman reagent with an alkyl halide occur in two steps, not by an Sj 2 mechanism. A two-step sequence occurs when a dialkyl cuprate reacts with an alkyl iodide. 

---