www.elsevier.com/locate/carres Carbohydrate Research 335 (2001) 23 – 32 (Chemo)enzymatic synthesis of dTDP-activated 2,6-dideoxysugars as building blocks of polyketide antibiotics Stefan Amann, a Gerald Dra ¨ger, b Carsten Rupprath, a Andreas Kirschning, b Lothar Elling a, * a Institute of Enzyme Technology, Heinrich -Heine -Uniersity, Du ¨sseldorf Research Center Ju ¨lich, D -52426 Ju ¨lich, Germany b Institute of Organic Chemistry, Uniersity of Hannoer, D -30167 Hannoer, Germany Received 11 April 2001; accepted 10 July 2001 Abstract The flexible substrate spectrum of the recombinant enzymes from the biosynthetic pathway of dTDP--L-rhamnose in Salmonella enterica, serovar typhimurium (LT2), was exploited for the chemoenzymatic synthesis of de- oxythymidine diphosphate- (dTDP-) activated 2,6-dideoxyhexoses. The enzymatic synthesis strategy yielded dTDP-2- deoxy--D-glucose and dTDP-2,6-dideoxy-4-keto--D-glucose (13) in a 40–60 mg scale. The nucleotide deoxysugar 13 was further used for the enzymatic synthesis of dTDP-2,6-dideoxy--L-arabino -hexose (dTDP--L-olivose) (15) in a 30-mg scale. The chemical reduction of 13 gave dTDP-2,6-dideoxy--D-arabino -hexose (dTDP--D-olivose) (1) as the main isomer after product isolation in a 10-mg scale. With 13 as an important key intermediate, the in vitro characterization of enzymes involved in the biosynthesis of dTDP-activated 2,6-dideoxy-, 2,3,6-trideoxy-D- and L-hexoses can now be addressed. Most importantly, compounds 1 and 15 are donor substrates for the in vitro characterization of glycosyltransferases involved in the biosynthesis of polyketides and other antibiotic/antitumor drugs. Their synthetic access may contribute to the evaluation of the glycosylation potential of bacterial glycosyl- transferases to generate hybrid antibiotics. © 2001 Elsevier Science Ltd. All rights reserved. Keywords: Nucleotide deoxysugars; dTDP--L-olivose; dTDP--D-olivose; Antibiotics; Macrolides 1. Introduction D- and L-deoxyhexoses are important con- stituents of glycoconjugates with biological functions in animals, plants, and microorgan- isms. 1 In general, all of them can be classified as 6-deoxy-D- and L-hexoses. Deoxygenation at C-2, C-3, and C-4 of the 6-deoxy-hexoses and modifications by amino-, N -methyl-, O - methyl-, and C -methyl-groups create a struc- tural diversity, which is encoded by distinct biosynthetic pathways of deoxythymidine diphosphate- (dTDP-), cytidine diphosphate- (CDP-), and guanosine diphosphate- (GDP-) activated sugars and the substrate specificity of glycosyltransferases. 2,3 In secondary meta- bolites of actinomycetes D- and L-deoxy- hexoses contribute to their antibiotic and anti- tumor bioactivity. Among the polyketide antibiotics these are mainly 2,6-dideoxy- hexoses besides 2,3,6-trideoxy sugars, which are dTDP-activated and donor substrates of * Corresponding author. Fax: +49-2461-612490. E -mail address: l.elling@fz-juelich.de (L. Elling). 0008-6215/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved. PII:S0008-6215(01)00195-1