An Elimination-Rearrangement of Ribulose-l,5-bisphosphate with Implications for Riboflavin Biosynthesis ... David HG Crout and John A. Hadfield Department of Chemistry, University of Warwick, Coventry CV4 7AL, U. K. ... Ribulose-1,5-bisphosphate (5) undergoes a sequence of elimination and benzilic acid rearrangement in a process with features that parallel those of the rearrangement occurring during incorporation of pentose precursors into riboflavin (1).