Indanomycin Antibiotic

A refined version of this reaction was used to obtain opticaliy active 3 from glycal 2. This product is readily converted to the tetrahydropyran 4, a subunit of the antibiotic indanomycin. 

Thus, (S,S)-tartaric acid (77) has been employed for constructing part of the structure of the antibiotic, indanomycin (ref.77). 

Most applications of the intramolecular Diels-Alder reaction use 1-substituted butadienes and these reactions often form a key step in the synthesis of polycyclic natural products. Substituents in the connecting chain may influence the facial selectivity of the cycloaddition reaction, as well as the endo. exo selectivity. For example, in a synthesis of the antibiotic indanomycin, the triene 83 gave, on heating. 

Having thus established the main stereochemical features, the Claisen rearrangement of glycal esters could be further utilized to provide key intermediates for a number of natural product syntheses Carbohydrates served as starting materials in the total synthesis of the ionophore antibiotics lasalocid A 43 by Ireland et al. [15] and indanomycin 46 by Ley et al. [16] (Scheme 8), as well as the 3-acyl tetramic acid antibiotics tirandamycic acid 49 [17] and (+)-streptolic acid 52 [18] (Ireland et al.. Scheme 9). Several further examples have been reported in the literature [19-21]. 

Danishefsky S, DeNinno S, Lartey P. A concise and stereoselective route to the predominant stereochemical pattern of the tetrahydropyranoid antibiotics an application to indanomycin. J. Am. Chem. Soc. 1987 109 2082-2089. 

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