Silanediol-based peptide mimics have been found to be low nanomolar inhibitors of metallo and aspartic proteases.  Development of these inhibitors is dependent on the efficient assembly of the silane structures with full control of stereochemistry.  We have developed a new set of chemistry that delivers key intermediates in enantiomerically pure form.  The application of this chemistry to the preparation of inhibitors of anthrax lethal factor and angiotensin-converting enzyme (both metalloproteases) will be described.