Streptobiosamic acid monolactone

Hydrolysis with aqueous mercuric chloride in the presence of cadmium carbonate removed the thioethoxy groups in ethyl tetraacetyl-thiostreptobiosaminide diethyl mercaptal. Crystalline tetraacetylstrep-tobiosamine was obtained in this manner. Bromine oxidation of tetraacetylstreptobiosamine in the presence of strontium carbonate yielded an acid which, after reacetylation, was obtained as the crystalline pentaacetyl derivative. The analytical data and the results of potentio-metric titrations for this oxidation product, designated pentaacetyl-streptobiosamic acid monolactone, were in agreement with the formula, Ci3Hi6NOio(CH3CO)5, required for a dibasic acid monolactone. A crystalline monomethyl ester of the substance was prepared. The established formula shows that all hydroxyl groups present are acetylated or lactonized. 

Assuming structure XXIII for streptosonic acid monolactone and structure XX for didesoxydihydrostreptobiosamine, streptobiosamic acid monolactone would be XXVI. 

Unlike the other streptobiosamine derivatives (Table IV, page 383) streptobiosamic acid monolactone formed a pentaacetyl derivative " rather than a tetraacetyl compound. Also, acetylation of streptosonic acid monolactone yielded a diacetyl derivative. It was pointed out that either the ordinarily resistant tertiary hydroxyl group had been acetylated in these compounds (XXVII) or that the lactone ring had shifted from the 7- to the /3-position, during the acetylation, with the introduction of an acetyl group at carbon atom four (XXVIII). Whatever the positions of the ester groupings in pentaacetylstreptobiosamic... 

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See also in sourсe #XX -- [ ]

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