Grignard reagents unsaturated, structures

The stereochemical course of reduction of imonium salts by Grignard reagents was found to depend on the structure of the reagent 714). Hydro-boration of enamines and oxidation with hydrogen peroxide led to amino-alcohols (7/5). While aluminum hydrogen dichloride reacted with enamines to yield mostly saturated amines and some olefins on hydrolysis, aluminum hydride gave predominantly the unsaturated products 716). 

The mechanism of the enantioselective 1,4-addition of Grignard reagents to a,j3-unsaturated carbonyl compounds promoted by copper complexes of chiral ferrocenyl diphosphines has been explored through kinetic, spectroscopic, and electrochemical analysis.86 On the basis of these studies, a structure of the active catalyst is proposed. The roles of the solvent, copper halide, and the Grignard reagent have been examined. 

Cyclic halo ethers also undergo reaction with Grignard reagents. 3-Chloro-tetrahydro-2-propylpyran is formed in 73% yield from 2,3-dichlorotetrahydro-pyran and propylmagnesium bromide.345 In a reaction analogous to the Boord synthesis, compounds of this structure are readily cleaved by sodium to the unsaturated alkanols 345,346... 

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