Open AccessPlanarity of heteroaryldithiocarbazic acid derivatives showing tuberculostatic activity. II. Crystal structures of 3‐[amino(pyrazin‐2‐yl)methylidene]‐2‐methylcarbazic acid esters
Author(s) -
Olczak Andrzej,
Szczesio Małgorzata,
Gołka Jolanta,
Orlewska Czesława,
Gobis Katarzyna,
Foks Henryk,
Główka Marek L.
Publication year - 2011
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
eISSN - 1600-5759
pISSN - 0108-2701
DOI - 10.1107/s0108270110049905
Subject(s) - planarity testing , chemistry , hydrogen bond , amide , stereochemistry , amino acid , crystal structure , crystallography , molecule , organic chemistry , biochemistry
Four compounds showing moderate antituberculostatic activity have been studied to test the hypothesis that the planarity of the 2‐[amino(pyrazin‐2‐yl)methylidene]dithiocarbazate fragment is crucial for activity. N ′‐Anilinopyrazine‐2‐carboximidamide, C 11 H 11 N 5 , D 1, and diethyl 2,2′‐[({[amino(pyrazin‐2‐yl)methylidene]hydrazinylidene}methylidene)bis(sulfanediyl)]diacetate, C 14 H 19 N 5 O 4 S 2 , B 1, maintain planarity due to conjugation and attractive intramolecular hydrogen‐bond contacts, while methyl 3‐[amino(pyrazin‐2‐yl)methylidene]‐2‐methyldithiocarbazate, C 8 H 11 N 5 S 2 , C 1, and benzyl 3‐[amino(pyrazin‐2‐yl)methylidene]‐2‐methyldithiocarbazate, C 14 H 15 N 5 S 2 , C 2, are not planar, due to methylation at one of the N atoms of the central N—N bond. The resulting twists of the two molecular halves (parts) of C 1 and C 2 are indicated by torsion angles of 116.5 (2) and −135.9 (2)°, respectively, compared with values of about 180° in the crystal structures of nonsubstituted compounds. As the methylated derivatives show similar activity against Mycobacterium tuberculosis to that of the nonsubstituted derivatives, maintaining planarity does not seem to be a prerequisite for activity.