DOTTADs – readily made novel metal ligands with multivariant functionality

Abstract

The interaction of Hantzsch pyridinecarboxylic acids with dialkylformamides and POCl₃, followed by treatment with NH₄OH yields 1,8-dioxo-1,2,7,8-tetrahydro-2,7,10-triazaanthracenes (DOTTADs), which have great potential as useful ligands for Group I and II metals and some transition metals. The corresponding Hantszch esters similarly give DOTTADs or their bis-imines by way of isolable intermediates, which are then treated with an amine RNH₂. DOTTAD-imines are also available from DOTTADs with amines and this reaction is also effective with 1,8-diamino-3,6-dioxaoctane to give macrocyclic analogues, as well as with chiral amines. DOTTAD-imines can be reduced with diethylsilane and Wilkinson's catalyst to the corresponding amines, which can also be formed from DOTTADs by reductive amination with amines and Na(AcO)₃BH. Mono-aldols of DOTTADs are easily formed by treatment of DOTTADs with acetone.