1,4-ASYMMETRIC INDUCTION IN THE CHROMIUM(II)-MEDIATED AND INDIUM-MEDIATED COUPLING OF ALLYL BROMIDES TO ALDEHYDES

A series of allyl bromides bearing an ethereal stereogenic substituent at C-2 were synthesized from methyl acrylate. These were coupled with a range of aldehydes under chromium(II) chloride-mediated conditions to afford syn-4-alkoxyalkan-1-ols in good yield and diastereoselectivi ty. The effect of altering the nature of the ethereal group and alkyl substituent upon the diastereoselectivity of the reaction was also inv estigated. The relative stereochemistry was proved by X-ray structure analysis. The work was extended to replace the chromium(II) chloride w ith indium metal, and this also afforded syn-4-alkoxyalkan-1-ols in go od yield and diastereoselectivity.