No abstract

The selective total synthesis of the pure Z-isomer of BOX A (8a), a product of oxidative heme degradation with significant physiological impact, was achieved in four to six steps starting from 3-bromo-4-methylfuran-2,5-dione (1). Z-BOX A forms a strong hydrogen bridge framework in the crystalline state. LC-MS techniques allow identification and characterization of isomeric forms of BOX A.

A novel [FeFe]-hydrogenase model complex containing phosphine oxide in the dithiolato ligand, namely [Fe2(CO)6]­[(μ-SCH2)2(Ph)­PO] (1), has been synthesized and characterized. Complex 1 was prepared via the reaction of equimolar quantities of (μ-LiS)2Fe2(CO)6 and OP­(Ph)­(CH2Cl)2. The protonation properties of complex 1 have been investigated by monitoring the changes in IR (in the ν­(CO) region) and 31P­{1H} NMR spectra upon addition of pyridinium tetrafluoroborate, [HPy]­[BF4], and HBF4·Et2O, suggesting protonation of the PO functionality. In addition, high-level DFT calculations on the protonation sites of complex 1 in CH2Cl2 have been performed and support our experimental observations that the PO unit is protonated by HBF4·Et2O. Cyclic voltammetric experiments on complex 1 showed an anodic shift of the oxidation peak upon addition of HBF4·Et2O, suggesting a CE process.

This work presents a new, size-independent, fast, mass based MP-analysis of PVC, ABS and PA 6.6 using quantitative 1H-NMR spectroscopy.