Template-Directed Synthesis of an Inverted Spiro Architecture.

The regular bicyclic spiro motif is highly abundant given its synthetic accessibility while the diastereomer-virtually obtained through inversion at the central atom-is almost unknown. We have developed methodology to access the elusive inverted spiro architecture by employing a covalent template-directed approach. Comparison with the regular spiro bicycle analog unequivocally established the diastereomeric relationship, providing insight into the fascinating stereochemical and structural properties.