7‐Oxo‐deacetamidocolchiceine and 7‐Benzylimino‐deacetamido‐colchiceine: Two novel products from the base catalysed reaction of (−)‐N‐Benzylidene‐deacetylcolchiceine

Abstract

SociCte suisse de chimie, Bile -Societh svizzera di chimica, Basilea ') The nomenclature chosen derives from the terms colchicine and isocolchicine [ 11. Thus compound 4 is named (f )-deacetamidocolchiceine, rather than ( f )-trimethylcolchicinic acid, a term frequently encountered. Visiting scientist on leave from the

The structure and absolute configuration of viridicatumtoxin: 2'S-(2'α,7'aβ,11'aβ,12'β)-7',7'a,8',11',11'a,12'-hexahydro-5',6',7'a,10',11'a,12'-hexahydroxy-3'-methoxy-2,6,6-trimethyl-7',8'-dioxospiro[2-cyclohexene-1,2'(1'H)-cyclopenta[de]naphthacene]-9'-carboxamide methanolate

“…1 for viridicatumtoxin and as appears to be the case in the OR TEP drawings published by Stezowski (1976), and Palenik, Mathew & Restivo (1978). If tautomeric mixtures were present, one might expect the apparent maximal directions of the thermal ellipsoids to be in the plane of the bonds, as was the case in the tautomeric mixture of tropolones reported by Iorio, Brossi & Silverton (1978). The averages corroborate Stezowski's (1976) observation, based on Nos.…”

Structural studies of colchicine derivatives. III. Structure of 7-deacetamidocolchiceine, C19H20O5

“…In the relationship between the molecular geometry of colchicine derivatives and their biological activity (antimitotics) (R6sner et aI., 1981;Santav~,l 1979), the arrangement of the oxygen substituents on the tropolonic ring may be relevant. In this respect, contrary to previous ideas, colchiceine (Silverton, 1979) has been found to exist in the solid state in the colchicine form (I), but 7-oxodeacetamidocolchiceine exists as an unusual 3:2 mixture of the possible tautomers (Iorio, Brossi & Silverton, 1978). Now, the results of the present work indicate that the simpler derivative, 7-deacetamidocolchiceine, belongs to the isocolchicine series (II).…”

“…From our results and those published by other authors (Silverton, 1979;Iorio, Brossi & Silverton, 1978;Margulis, 1982) it seems that the absence of any substitution at position 7 in eolchiceine derivatives may favour, in the solid state, the isocolchicine-like arrangement of the oxygen substituents on the tropolonic ring C.…”

2:1 Adduct of colchiceine acetate and ethyl acetate

“…A third possibility, i.e. the existence of a colchicine analogue with a crystalline structure consisting of a mixture of the two tautomeric forms, is represented by 7-oxo-deacetamidocolchiceine (Iorio et al, 1978).…”

“…A third possibility, i.e. the existence of a colchicine analogue with a crystalline structure consisting of a mixture of the two tautomeric forms, is represented by 7-oxo-deacetamidocolchiceine (Iorio et al, 1978).Further work is now in progress in order to determine the influence of the acyl groups in the acylotropic tautomerism of colchiceine esters and its relation with their crystal structure. …”