Scheme 3 Synthesis of 1 via a Weinreb amide here shown with the modifications of the Taylor group. 17Scheme 4 1 and 8 as precursors for the and -2-aminohydroxypropyl structural element.

Functionalized compounds, which are difficult to produce by classical chemical synthesis, are of special interest as biotechnologically available targets. They represent useful building blocks for subsequent organic syntheses, wherein they can undergo stereoselective or regioselective reactions. "White Biotechnology" (as defined by the European Chemical Industry [ http://www.europabio.org/white_biotech.htm ], as part of a sustainable "Green Chemistry,") supports new applications of chemicals produced via biotechnology. Environmental aspects of this interdisciplinary combination include: Use of renewable feedstock Optimization of biotechnological processes by means of: New "high performance" microorganisms On-line measurement of substrates and products in bioreactors Alternative product isolation, resulting in higher yields, and lower energy demand In this overview we describe biotechnologically produced pyruvic, 2-oxopentaric and 2-oxohexaric acids as promising new building blocks for synthetic chemistry. In the first part, the microbial formation of 2-oxocarboxylic acids (2-OCAs) in general, and optimization of the fermentation steps required to form pyruvic acid, 2-oxoglutaric acid, and 2-oxo-D-gluconic acid are described, highlighting the fundamental advantages in comparison to chemical syntheses. In the second part, a set of chemical formula schemes demonstrate that 2-OCAs are applicable as building blocks in the chemical synthesis of, e.g., hydrophilic triazines, spiro-connected heterocycles, benzotriazines, and pyranoic amino acids. Finally, some perspectives are discussed.

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The 2‐nitrophenylhydrazones 2 of D‐arabino‐2‐hexulopyranosonic acid, D‐arabinose, D‐galactose and D‐galacturonic acid are used as precursors to form chiral functionalized 1,2,4‐benzotriazines and benzimidazoles by reductive cyclization methods. Catalytic hydrogenation provided the amine derivatives which are cyclized and air oxidized in alkaline solution to yield the novel 1,2,4‐benzotriazines 3 as the main products, while on acid catalysis the benzimidazoles 4 are formed.

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Dedicated to Professor Klaus Burger on the occasion of his 60th birthday Methyl β‐D‐arabono‐2‐hexulopyranosonate 1 has via the novel glycosyl donor 3 been transformed into the thiophenyl glycosides 4 and 5. Catalytic hydrogenation of the nitro compound 4 in alkaline solution led to spontaneous cyclization and deprotection to form the cyclic hydroxamic acid 7. The related lactams 8 and 9 were obtained from amine 5. The spiro[1,4‐benzothiazine‐2,2′‐pyrans] 7–9 are the first representatives of a novel class of heterocycles structurally related to bioactive natural products. As shown by the values for J3′,4′ and J4′,5′ the glycosides 4, 5 and 6 adopt a 5C2 conformation of the pyranoid ring whereas the 1,4‐benzothiazine system in 7–9 forces a conformational change into the 2C5 conformation.