Cyclometalation of Anthyridine-Based Ligands with Dirhodium Acetates: Structure and Catalytic Activity
摘要:
Coordination of 2,8-Ar-2-5-phenylanthyridines (Ar = 2-thienyl, 1a; Ar = 2-ClC6H4-, 1b) with dirhodium tetraacetate yielded the cyclometalated complexes [Rh-2(OAc)(3)(metalated-1a)] (3a) and [Rh-2(OAc)(3)(metalated-1b)] (3b), respectively. Under acidic conditions, cleavage of the Rh-C bond in 3a,b took place to give the corresponding coordination complexes 4a,b. Treatment of 3a,b with PPh3 led to the phosphine-cyclometalated species [Rh-2(OAc)(2){P,C-(C6H4)PPh2)(metalated-1a)] (5a) and [Rh-2(OAc)(2){P,C-(C6H4)PPh2}(metalated-1b)] (5b), respectively. These new dirhodium complexes have been structurally characterized by NMR spectroscopy, and some representative compounds were also analyzed by X-ray methods. The use of these newly prepared dirhodium complexes as catalysts for the allylic oxidation of cydohexenes was investigated.
Synthesis of heterocyclic compounds containing three contiguous hydrogen bonding sites in all possible arrangements
摘要:
The synthesis of compounds containing three contiguous hydrogen bond sites is reported. There are six ways of arranging three adjacent hydrogen bond donor (D) and acceptor (A) sites. General synthetic routes to heterocyclic compounds with each arrangement is reported.