The oxa-Michael reaction: from recent developments to applications in natural product synthesis.

In marked contrast to Michael reactions, oxa-Michael reactions have not been used as standard transformations in organic synthesis until quite recently. This was mainly due to a lack of reactivity and selectivity, although the potential products of such reactions are valuable intermediates. This tutorial review presents recent major advances in the field of oxa-Michael (sometimes called oxo-Michael or oxy-Michael) reactions and applications in the total synthesis of complex natural products.