Synthesis of (±) Wine Lactone and Its Analogues by a Diels–Alder Approach

Abstract

AbstractA novel route to (±)‐wine lactone (1) by a cis‐selective kinetically controlled intramolecular Diels–Alder (IMDA) cycloaddition of the linear triene 2 is reported. The triene precursor was synthesised by TBAF‐catalysed coupling of an acyl fluoride with an silyl enol ether. Four butadienyl but‐3‐enoates were prepared and cyclised under mild conditions to give a series of wine lactone analogues. The diastereoselectivity of the IMDA cycloadditions was determined by NMR spectroscopy and GC‐MS, whereby the formation of the natural cis‐configured wine lactone (1) was established. The diastereomeric IMDA transition states were optimised by using density functional theory at the B3LYP/6‐31+G(d) level, and the Boltzmann populations of the electronic energies were found to correlate well with the experimentally observed diastereoselectivity.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)