Intramolecular Silanoxy-Michael Reactions with Pendant Nitroalkenes, Racemic and Enantioselective

We present the first racemic and scalemic examples of di-tert-butyl silanoxy Michael additions. Our operationally simple protocol is selective for nitro-olefins and simply involves stirring substrate with an appropriate hydrogen-bond donor catalyst without any special precautions to exclude air or moisture. For each substrate examined, we have developed complementary protocols which respectively optimize yield and enantioselectivity. Our reactions scale well, and the products are valuable intermediates for further transformations, including for the preparation of enantioenriched vicinal amino-alcohols.