Abstract
A further member of 2,4,6‐trialkyl‐phenyl‐phos‐pholes, the di__tert__butylmethylphenyl derivative (1c) was characterized by Bird index and by the sum of angles at the phosphorus atom to describe the flattening of the P‐pyramid. Both numbers suggested a slight aromaticity. The reaction of arylphospholes with phosphorus tribromide was extended to phosphole 1c leading this occasion, after further steps, to the mixture of 3‐ and 2‐substituted products (3c‐1 and 3c‐2, respectively). A triisopropylphenyl‐2__H__‐phosphole (4) formed by sigmatropic rearrangement was utilized in the preparation of new 1‐phosphanorbornene derivatives, such as sulfide 6 and hemi‐oxides 8‐1 and 8‐2. Further oxidation of the latter species (8‐1 and 8‐2) led to the decomposition of the dimeric structure (11). 4 could also be trapped by benzaldehyde to afford the oxaphosphanorbornene (10) as one diastereomer. Finally, the reversible formation of 2__H__‐phosphole 4 from 1__H__‐phosphole 1a at 150°C was proved. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:104–222, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20077