2,4,6‐Trialkylphenyl‐2<i>H</i>‐phospholes from slightly aromatic 1<i>H</i>‐phospholes and their use in [4 + 2] cycloaddition reactions

Abstract

Abstract 1‐(2,4,6‐Trialkylphenyl)phospholes 1a,b possess a moderate aromatic character. Despite of that they underwent a sigmatropic rearrangement at 150°C to afford 2H‐phospholes 2a,b which by trapping with tolane, or in reaction with another unit of 2 gave [4 + 2] cycloadducts 3a,b , or in a reversible reaction, dimer 6 , respectively. Dedimerization of species 6 at 150°C in the presence of tolane, or at 0°C under oxidative circumstances, led to 1‐phosphanorbornadiene 3a , or phosphole oxide dimer 8 , respectively. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:316–319, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10151