Fortuitous Enantiomeric Self‐Rectification of an Unreported Partial Racemisation in the Synthesis of a Chiral Phosphoric Acid: A Warning to Practitioners.

<bold>Racemisation without Consequence</bold>: MOM deprotection during a routine synthesis of phosphoric acid <bold>1</bold> promoted partial racemisation of the product BINOL <bold>5</bold>. Surprisingly, however, after phosphorylation of the partially racemised BINOL, <italic>enantiopure</italic> acid <bold>1</bold> was isolated. Further inspection revealed that during phosphorylation, unhydrolysed racemic phosphorochloridate <bold>6</bold> precipitated, thus restoring homochirality in the product phosphoric acid <bold>1</bold>. Moreover, MOM deprotection partial racemisation was avoided by conducting reactions at lower temperatures for no longer than the required deprotection time, and/or by application of other deprotection conditions from the literature. [ABSTRACT FROM AUTHOR]