Synthetic Studies on the Carbomycins (Magnamycins): An Exception to the Enantioselective Synthesis of β-Alkyl Carboxylic Acids via Chiral Oxazolines

Article abstract of DOI:10.1021/jo00332a023

We have observed that α,β-unsaturated oxazolines 9, bearing a β-glucose unit, when treated with allylic lithium reagents, give stereoselectivity that is opposite that predicted by Meyers' arguments.Alkyllithium reagents add in the predicted manner.Unsaturated ester 10, when treated with lithium diallylcuprates, gives the same relative stereochemistries as are afforded by the alkyllithium reagents with oxazoline 9.Lithium dialkylcuprates, when added to 10, provide the stereochemistry obtained by treating oxazolines 9 with allyllithiums.Both allyllithiums and alkyllithiums add to oxazoline 15 in the manner predicted by Meyers.