Benign synthesis of terpene-based 1,4-p-menthane diamine.

Terpenes represent a promising renewable feedstock for the substitution of fossil resources in the synthesis of renewable platform chemicals, like diamines. This work describes the synthesis and full characterization of 1,4-p-menthane diamine (1,4-PMD) obtained from α-terpinene (1). A two-step procedure using dibenzyl azodicarboxylate (DBAD) and H2 as rather benign reagents was employed under comparatively mild conditions. Both C-N bonds were formed simultaneously during a visible-light mediated Diels-Alder reaction, which was investigated in batch or flow, avoiding regioselectivity issues during the amination steps that are otherwise typical for terpene chemistry. Heterogeneously catalyzed quadruple hydrogenation of the cycloadduct (2a) yielded 1,4­PMD (3). While the intermediate cycloadduct was shown to be distillable, the target diamine can be sublimed, offering sustainable purification methods.

Investigation of the Coordination Chemistry of a Bisamidinate Ferrocene Ligand with Cu, Ag, and Au.

The coordination chemistry of a ferrocene ligand with one bulky amidinate function attached to each ring toward two different coinage metal precursors was investigated. In dependence of the metal and the co-ligands, "ansa" type structures and non-bridged structures were obtained. Six different compounds are reported. In the "ansa" type structures, short Fe-M (M = Cu, Ag) distances were observed in the molecular structures in the solid state. However, theoretical calculations (DFT) did not reveal a stabilizing metal-metal interaction. Instead, dispersion interactions within the ligand and between the ligand and metal seem to represent the main stabilization forces.