Synthesis of methylerythritol phosphate analogues and their evaluation as alternate substrates for IspDF and IspE from Agrobacterium tumefaciens.

The methylerythritol phosphate biosynthetic pathway, found in most Bacteria, some parasitic protists, and plant chloroplasts, converts D-glyceraldehyde phosphate and pyruvate to isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), where it intersects with the mevalonate pathway found in some Bacteria, Archaea, and Eukarya, including the cytosol of plants. D-3-Methylerythritol-4-phosphate (MEP), the first pathway-specific intermediate in the pathway, is converted to IPP and DMAPP by the consecutive action of the IspD-H proteins. We synthesized five D-MEP analogues-D-erythritol-4-phosphate (EP), D-3-methylthrietol-4-phosphate (MTP), D-3-ethylerythritol-4-phosphate (EEP), D-1-amino-3-methylerythritol-4-phosphate (NMEP), and D-3-methylerythritol-4-thiolophosphate (MESP)-and studied their ability to function as alternative substrates for the reactions catalyzed by the IspDF fusion and IspE proteins from Agrobacterium tumefaciens, which covert MEP to the corresponding eight-membered cyclic diphosphate. All of the analogues, except MTP, and their products were substrates for the three consecutive enzymes.

Double- and triple-consecutive O-insertion into tert-butyl and triarylmethyl structures.

[reaction: see text] The concecutive Criegee rearrangement reactions were studied for tert-butyl trifluoroacetate, triarylcarbinols, and benzophenone ketales with trifluoroperacetic acid (TFPAA) in trifluoroacetic acid (TFA). The formation of methyl acetate and methyl trifluoroacetate indicates that the consecutive double-O-insertion process has taken place for tert-butyl trifluoroacetate. The intermediate dimethoxymethylcarbonium ion was detected below 5 degrees C. A consecutive triple-O-insertion process has been observed for triarylmethanols and benzophenone ketals. A new high yield method of corresponding diaryl carbonates synthesis was developed.