N2S2 and N4S4 precursors to PS2 macrocycles and cyclic amidinium salts

Abstract

The cyclo-condensation of 1R,2R-diaminocyclohexane with 2,2′-(ethane-1,2-diyldisulfanediyl)dibenzaldehyde gave the 1 : 1 addition compound chxn-^imN₂S₂ in high yield. When the same condensation reaction was performed with 1R,3S-diamino-1,7,7-trimethylcyclopentane as the diamine, the 2 : 2 addition compound tmcp-^imN₄S₄ was obtained selectively. Reduction of the diimines gave the saturated analogues chxn-N₂S₂ (1) and tmcp-N₄S₄ (3) the former of which could be phosphorylated with PhP(NMe₂)₂ to give the novel 13-membered macrocycle chxn-PS₂, 2. Introduction of the phenylphosphine function proved stereoselective with a preference for the N(R)/N(S) configuration at the nitrogen atoms. The coordination chemistry of the novel phosphine has been explored with Cu(I) and Mo(0) through formation of the complexes Cu(2)I, 4, and Mo(CO)₃(2), 5. Extension of the phosphorylation chemistry to tmcp-N₄S₄ (3) proved unsuccessful but ring closure reactions of both 1 and 3 with triethylorthoformate gave cyclic amidinium salts which are potential precursors to macrocyclic N-heterocyclic carbenes.