158. Synthesis of uronic acids. Part III. d-Mannuronic acid

Mutarotation and ring structure of mannuronic lactone

“…The authors state that "the rapid initial increase is probably due to attainment of equilibrium between the a and {3 forms of the aldehyde, and the subsequent decrease is due to the formation of mannuronic acid." Subsequently, Ault, Haworth, and Hirst [11] reported an optical rotation of +95°, with no mutarotation, whereas Stacey and Wilson [12] reported a value of +50°, increasing to +94° in 30 minutes. The measurements obtained in the present investigation (table 2) show an …”

Synthesis, Characterization, and Crystal Structure of Sodium (Methyl α-d-Mannopyranosid)uronate Monohydrate

“…In connection with other work in this laboratory, a need arose for a convenient intermediate toward derivatives of methyl α-D-mannopyranosiduronic acid. As with other glycosides of hexuronic acids, older preparations of such compounds involve multistep synthesis 1,2 through oxidation of variously protected derivatives of methyl α-Dmannopyranoside (1). Isolation of products in these situations is usually straightforward because the desired product can be readily isolated from crude reaction mixtures by extraction into organic solvent and purification by chromatography.…”

“…9 Alkali metal salts of uronic acids are important intermediates to alkyl uronates, which are starting points toward more complex derivatives in these series. Here we describe the application of the method 8 for the preparation of sodium (methyl α-Dmannopyranosid)uronate (2), which is now described and fully characterized through its crystalline monohydrate 3 for the first time. Compared to protocols toward mannuronate intermediates developed earlier, the advantage of the one described here lies in that it does not require a pre-cious metal catalyst or protection and deprotection of intermediates, and gives the desired product in higher yield.…”