Robert Willens (Managing Director, Lehman Brothers, New York) has published Exceptions to the Application of the Attribution Rules:  Few and Far Between, 109 Tax Notes 923 (Nov. 14, 2005), also available on the Tax Analysts web site as Doc 2005-22291, 2005 TNT 219-42.  Here is the abstract:

A redemption of stock will be treated as a payment in exchange for the stock if the shareholder sustains a sufficient reduction of her proportionate interest in the corporation. That determination, is complicated by the fact that one’s "ownership" of stock encompasses not only stock that the shareholder actually owns but, thanks to section 302(c), stock the shareholder constructively owns. While the "attribution" rules are quite comprehensive, some narrow exceptions to their application do exist. One question that has yet to conclusively resolve is whether there exists a hostility exception to the application of these attribution rules.