Aerial oxidation of tetrahydrofuran to 2-hydroxotetrahydrofuran in the presence of a trimeric CuI complex [Cu3L3] (HL = tBuNHC(S)NHP(S)(OiPr)2) and trapping of the unstable product at recrystallization

Abstract

The reaction of the potassium salt of N-thiophosphorylated thiourea tBuNHC(S)NHP(S)(OiPr) 2 (HL) with Cu(NO 3 ) 2 in aqueous EtOH leads to the trinuclear [Cu 3 (tBuNHC(S)NP(S)(OiPr) 2 -S,S 0 ) 3 ] ([Cu 3 L 3 ]) complex. It was established that [Cu 3 L 3 ] provokes the aerobic oxidation of tetrahydrofuran to 2-hydroxotetrahydrofuran and traps the latter at crystallization.Scheme 1 Mono-oxygenation of THF.

Isolation of a 2-Hydroxytetrahydrofuran Complex from Copper-Promoted Hydroxylation of THF

“…Isotope labeling studies indicate that the hydroxide O-atom in 3 transfers to the THF-2-ol ligand in the product. This reaction is a rare example of THF hydroxylation by a copper moiety, 12,13 and contrasts with previous reports insofar as it yields a copper complex of the product and does not involve Cu/O 2 chemistry.…”

“…The unique transformation yielding 4 complements the few previous reports of the hydroxylation of THF from species derived from reactions of Cu I complexes with O 2 . 12,13 …”

Hydrogen Atom Abstraction from Hydrocarbons by a Copper(III)-Hydroxide Complex

“…The attack of 1 at the C–H bonds of THF represents a rare example of oxidation of THF by a copper–oxygen species. 25 The reactions of a [CuOH] 2+ moiety with strong C–H bonds and, in particular, such bonds α to an ether functionality in THF, is notably relevant to proposals for glycoside cleavage by the copper-containing enzyme lytic polysaccharide monooxygenase (LPMO, Figure 8 ). 3h , 26 The active site of LPMO contains a single copper ion in a tetragonal geometry with meridional binding of a monodentate His imidazolyl and a bidentate motif called a “histidine brace” comprising an imidazolyl and amino group.…”

Novel bicyclic hexanuclear copper(I) aggregate: Structure and solid state 31P CPMAS NMR spectra of [(Cu3L3)2] and [Cu(PPh3)2L] complexes of N-(diisopropoxythiophosphinyl)-N′-phenylthiourea (HL)

“…As it was established recently, the formation of the completely different type of [Cu n L n ] complexes in a crystal phase take place depending on a structure of the assistant at R in fragment RC(S)NHP(S)(OiPr) 2 groups in the identical experimental conditions. The formation of the trimeric (R = tBuNH [29]), tetranuclear (R = Me 2 N [29], Ph [30]) cyclic associates as well, as hexanuclear (R = NH 2 [31]) and octanuclear (R = iPrNH [29]) polycyclic associates has been found.…”

“…The solid state31 P{ 1 H} CPMAS NMR spectrum of the mononuclear complex [Cu(PPh 3 ) 2 L] (2) (A). Expansion of the experimental (B) and simulated J-multiplet patterns (C) of the PPh 3 ligands.…”