George O. Morton

Structures of methyl aldgarosides A and B obtained from the neutral macrolide antibiotic aldgamycin E

Abstract The methanolysis of aldgamycin E yields, in addition to methyl mycinoside, two anomeric carbonate containing methyl glycosides, A and B. The structures of the two carbonate sugars have been elucidated and found to belong to the D series.

Reactions of the trisulfide moiety in calicheamicin

Abstract Calicheamicin γ1I ( 1 ) reacts with Ph3P to form a dimeric trisulfide ( 3 ), MeSSMe, Ph3PS, and Ph3PO, as well as an aromatic degradation product ( 2 ). The oxygen of the Ph3PO is derived from O2. Calicheamicin also reacts with thiols to produce disulfides (eg. 4 ) with high selectivity. Dimeric trisulfide 3 is generated during this reaction.

A trimeric l-ristosamine-ammonia condensation-product

Abstract Three molecules of l -ristosamine (3-amino-2,3,6-trideoxy- l - ribo -hexopyranose) condense with one molecule of ammonia to give a stable compound [1.1′.1′′-(dodecahydro-1,4,7,9 b -tetrazaphenalene-2,5,8-trityl)tri-1,2-propanediol] reminiscent of the mode whereby formaldehyde and ammonia condense to form hexamethylenetetramine. The structure of the crystalline hexaacetate of this compound has been determined by X-ray crystallography. The mass-spectral fragmentation pattern and the 13 C-n.m.r. signals shown by the acetylated compound are assigned.

Conversion of a pimarane diterpene into the cleistanthane ring system

The acid-catalysed migration of the C-13 vinylidene grouping to C-14 in a pimarane diterpene is reported.