The synthesis of two new chiral sigma(2)lambda(2)-phosphenium cations 3 and
9 bearing proximal methoxy groups and their corresponding phosphine-borane
adducts is reported. Phosphenium 9 has been successfully used in a chelotr
opic cycloaddition reaction with 2,3-dimethyl butadiene leading to the form
ation of a new sigma(4)lambda(4)-adduct. (C) 1999 Elsevier Science Ltd. All
rights reserved.