Struktur und Reaktivität eines Triazolobenzodiazepin/Oxalylchlorid‐Addukts

Abstract

Structure and Reactivity of a Triazolo‐benzodiazepine/Oxalyl Chloride AdductReaction of oxalyl chloride with N, N‐dimethyl‐{8‐chloro‐6‐(0‐fluorophenyl)‐ 4H, 11 H‐[1,2,4]triazolo [1,5‐α] [1,4]benzodiazepine}‐2‐carboxamide (6a), the syn‐thesis of which is described, leads to the cyclic adduct N, N‐dimethyl‐{2,12,12‐trichloro‐13a‐(0‐fluorophenyl)‐11‐oxo‐10,11,12,13a‐tetrahydro‐5H, 9H‐[1,3]oxazolo [3,2‐d] [1,2,4]triazolo [1,5‐a] [1,4]benzodiazepine}‐7‐carboxamide (7a). Upon thermolysis 7a is partly reconverted to the starting diazepine 6a via loss of the elements of oxalyl chloride. Reduction of 7a with sodium borohydride also yields 6ain addition to its dihydro derivative 9. Energetic treatment of 7a with sodium methoxide leads to the unexpected methoxydiazepines 10a and 10b, and mild treatment of 7a with sodium methoxide to the stereoselective formation of the two precursors of 10, namely the chloromethoxy derivative 11 and the dimethoxy derivative 12. Epimerization of 11 followed by nucleophilic substitution gives a mixture of two dimethoxy compounds, 12 and its epimer 14. The configurational assignments of these derivatives are based upon X‐ray analysis of 12. A possible pathway for this unexpected substitution reaction is proposed.