Applications of Bifunctional Organocatalysts on ortho‐Quinone Methides

Abstract ortho ‐Quinone methides are important structures, having a cyclohexadiene core bearing an exocyclic alkylidiene and carbonyl functionality at the ortho ‐position, and are widely used as essential intermediates in organic synthesis. These reactive intermediates are also used as important building blocks for the construction of a variety of heterocycles by hetero Diels‐Alder, electrocyclization reactions. Moreover, ortho ‐quinone methides are a class of electrophiles, serving as Michael acceptors leading to conjugate additions with various nucleophiles. In general, ortho ‐Quinone methides have transient existence and are highly reactive in nature. ortho ‐Quinone methides have been generated in situ from stable precursors using either Brønsted acids or Brønsted bases. In the last few years, ortho ‐quinone methides have been explored as imperative class of substrates in various bifunctional organocatalysts mediated asymmetric conjugate additions, cycloannulation, acyl‐transfer reaction, thiolation and hydrophosphination reactions. This review illustrates recent advancements of asymmetric transformations of ortho ‐quinone methides with bifunctional H‐bonding organocatalysts.