Studies related to a synthetic approach to nootkatin

Abstract

The aim of this research is the synthesis of the naturally occurring tropolone, nootkatin. An account is given of a number of methods used in attempting to lengthen the dicarboxylic acid chain in a δ-lactam acid (2-oxo-4-isopropylpiperidine-5-carboxylic acid) with a view to subsequent cyclisation to a seven-membered carbon ring. The preparation of a malonate keto ester is described and its intended use in the synthesis of nootkatin is outlined. It is unlikely a better intermediate than the δ-lactam acid could be devised since it has suitable groups in the correct relative positions for an unambiguous synthesis. The probable stereochemistry of the δ-lactam acid and its derivatives is also discussed.