The Asymmetric Synthesis of 2,2-Dialkyl Carboxylic Esters and 2,2-Disubstituted Dihydronaphthalenes

Article abstract of DOI:10.1021/jo00297a032

The bicyclic lactams derived from (S)-valinol and 3-benzoylpropionic acid or levulinic acid are useful chiral precursors to the title compounds.Metalation of bicyclic lactams 1 and 4 and alkylation followed by acidic hydrolysis leads to racemic 2-alkyl carboxylic acids.However, sequential metalation-alkylation to 2,2-dialkyl bicyclic lactams 2 and 5 furnishes these systems with good diastereoselectivity.Treatment of 5 with triflic acid causes a facile rearrangement to the oxalines 7 and hydrolysis leads to the carboxylic esters.Under certain conditions, hydrolysis leads directly to naphthalenes 11.