The von Auwers reaction - history and synthetic applications.

Dienones obtained from the facile dearomatization of phenols, can be further transformed to semi-benzenes prone to rearomatize in clean, but sometimes unexpected, fashion. Over a hundred years ago, K. von Auwers found that adding Grignards on dienones would lead spontaneously to subsequent dehydration and a novel aromatizing rearrangement. This reaction was ignored for 50 years before Melvin Newman re-investigated these findings, studied the mechanism, and developed variations on the same theme. Since then, despite the tremendous potential of the reactions, those studies were only rarely mentioned, before finally falling into oblivion. This review aims to provide the reader with a detailed history and comprehensive bibliography of the von Auwers rearrangement, some of its synthetic applications, and new unpublished material in the hope to open new perspectives on this forgotten reaction.