Degradation acid, methylation structural analysis

Structure of xanthan has been determined by chemical degradation and methylation analysis (335,336) it is composed of repeating units consisting of a main chain of D-glucopyranosyl residues with trisaccharide side chains made up of D-mannopyranosyl and D-glucopyranosyluronic acid residues. 

The absolute configuration was also established unequivocally for C-8 of naturally occurring pyrrolizidine bases.88 It was demonstrated in the course of the structural analysis of isoheliotridene (146), obtained by degradation of the alkaloid monocrotaline, that ozonolysis of this compound affords 2-acetylpyrrolidine-l-acetic acid (147).66 The (— )-methyl ester of this acid was condensed with methylmagnesium iodide to give (— )-l-(2-hydroxy-2-methylpropyl)-2-(l-hydroxy-l-methylethyl)pyrrolidine (148). The same glycol (148) was obtained... 

This glycan was extracted by a trichloroacetic acid method and purified to homogeneity by alcohol precipitation and bio-gel filtration methods. The complete molecular structure of the glycan has been deduced from data of methylation analysis in combination with enzymic and chemical degradation reactions (25,... 

Codonocarpine (C26H3i05Ng mp 187°) is a new alkaloid structurally-related to lunarine. Hydrolysis generated spermidine, [H2N(CH2)3NH-(CH2)4NH2]. Spectral analysis indicated that its structure is 42 and chemical degradation was consistent therewith. Hydrolysis of the tetrahydro derivative of the 0-methyl derivative gave an acid whose properties were consistent with structure 43 (52). 

R = Ac] and milliamine B [74 R = R = H, R = (75)] have been isolated. The structure of milliamine A rests on spectral evidence and hydrolysis with sodium methoxide in methanol to the diterpene (74 R = R = R = H) and the methyl ester corresponding to part structure (75). The structure of the diterpene tetraol, (74 R = R = r3 = H) had been previously determined by X-ray crystallographic analysis the structure of the alkaloidal portion was established by further degradation with hydrochloric acid to methyl anthranilate and compound (76), which was found to be identical with an authentic sample... 

---