Catalytic asymmetric synthesis of 5-membered alicyclic α-quaternary β-amino acids via [3 + 2]-photocycloaddition of α-substituted acrylates

摘要

The photocatalytically active salt of a cationic iridium polypyridyl complex and a chiral borate is competent to promote a highly stereoselective [3 + 2]-cycloaddition of cyclopropylurea with a-substituted acrylates. This protocol provides straightforward access to a variety of stereochemically defined 5-membered alicyclic a-quaternary p-amino acids, useful building blocks of p-peptides and peptidomimetics.