Enzymatic Synthesis of a Ring-Contracted Analogue of 5-Enolpyruvylshikimate-3-phosphate

Recombinant AroL-Catalyzed Phosphorylation for the Efficient Synthesis of Shikimic Acid 3-Phosphate

Shikimic acid 3-phosphate, as a central metabolite of the shikimate pathway, is of high interest as enzyme substrate for 5-enolpyruvoyl-shikimate 3-phosphate synthase, a drug target in infectious diseases and a prime enzyme target for the herbicide glyphosate. As the important substrate shikimic acid 3-phosphate is only accessible via a chemical multi-step route, a new straightforward preparative one-step enzymatic phosphorylation of shikimate using a stable recombinant shikimate kinase has been developed for the selective phosphorylation of shikimate in the 3-position. Highly active shikimate kinase is produced by straightforward expression of a synthetic aroL gene in Escherichia coli. The time course of the shikimate kinase-catalyzed phosphorylation is investigated by ¹ H- and ³¹ P-NMR, using the phosphoenolpyruvate/pyruvate kinase system for the regeneration of the ATP cofactor. This enables the development of a quantitative biocatalytic 3-phosphorylation of shikimic acid. After a standard workup procedure, a good yield of shikimic acid 3-phosphate, with high HPLC- and NMR purity, is obtained. This efficient biocatalytic synthesis of shikimic acid 3-phosphate is superior to any other method and has been successfully scaled up to multi-gram scale.

A Tether Controlled exo-Selective Trans-Annular Diels−Alder (TADA) Reaction

[reaction: see text] A fully substrate controlled stereoselective route to construct cis-hexahydronaphthalene 4 is described starting from nonracemic butenolide 6. The key step is an exo-selective transannular Diels-Alder reaction (TADA) of tetraene 5, whose intrinsic constraint allows selective formation of one stereodefined product. Compound 4 is a key intermediate in the synthesis of the novel antibiotic branimycin (1).

Sphingolipid synthesis via olefin cross metathesis: preparation of a differentially protected building block and application to the synthesis of D-erythro-ceramide

The sphingolipid backbone is readily assembled by E-selective olefin cross metathesis of a suitable building block.

Novel A-ring analogs of the hormone 1α,25-dihydroxyvitamin D3: synthesis and preliminary biological evaluation

Prepared from a commercial prostaglandin building block, novel vitamin D3 analogs with a contracted five-membered A-ring were designed and synthesized to mimic the A-ring diol structure of the natural hormone 1alpha,25-dihydroxyvitamin D3. Prepared from commercial 1,4-cyclohexanedione, a structurally simplified analog was designed and synthesized in which a suitably oriented primary allylic hydroxyl group at the C-2 position might be a surrogate for the biologically important 1alpha-OH in the natural hormone.