Ligand-stabilized copper(I)-hydride catalyzes the dehydrogenative Si-O coupling of alcohols and silanes-a process that was found to proceed without racemization at the silicon atom if asymmetrically substituted. The present investigation starts from this pivotal observation since silicon-stereogenic silanes are thereby suitable for the reagent-controlled kinetic resolution of racemic alcohols, in which asymmetry at the silicon atom enables discrimination of enantiomeric alcohols. In this full account, we summarize our efforts to systematically examine this unusual strategy of diastereoselective alcohol silylation. Ligand (sufficient reactivity with moderately electron-rich monophosphines), silane (reasonable diastereocontrol with cyclic silanes having a distinct substitution pattern) as well as substrate identification (chelating donor as a requirement) are introductorily described. With these basic data at hand, the substrate scope was defined employing enantiomerically enriched tert-butyl-substituted 1-silatetraline and highly reactive 1-silaindane. The synthetic part is complemented by the determination of the stereochemical course at the silicon atom in the Si-O coupling step followed by its quantum-chemical analysis thus providing a solid mechanistic picture of this remarkable transformation.

A series of propargylic tertiary alcohols decorated with an sp2-hybridised nitrogen donor were kinetically resolved by reagent-controlled dehydrogenative Si-O coupling with a strained, highly reactive silicon-stereogenic cyclic silane.

Palladium triggered removal of a propargyl group leads to the cleavage of the 1,2-dioxetane ring, leading to bright chemiluminescence. The reaction of the probe is highly specific for the Pd species, thus the probe described here has considerable potential for practical utility. © The Royal Society of Chemistry.2015

Striking differences in the reactions of alkoxycarbene and thiocarbene complexes of chromium and tungsten are observed. Thus, (β-imino)ethoxycarbene complexes 10a−e, generated in situ from [(OC)5WC(OEt)CH2R] (7a−c; R = n-Pr, Me, c-C7H7) and imidoyl chlorides R1ClCNCHR2R3 (9a−f; R1 = t-Bu, Ph, 2-furyl; R2 = H, Me; R3 = Me, Et, Ph), undergo a metalla(di-π-methane) rearrangement to (N-enamino)ethoxycarbene complexes 12a−e, while the corresponding (β-imino)thiocarbene complexes 11a−l, derived from [(OC)5MC(SEt)CH2R] (8a−e; M = W, Cr; R = n-Pr, Me, c-C7H7, c-C6H7Fe(CO)3) and imidoyl chlorides under similar conditions, form pyrroles 16a−h and 17k,l by α-cyclization. On the basis of the calculated DFT/BP86 potential energy surfaces of the particular reaction channels it is shown that (β-imino)alkoxycarbene compounds 10 prefer a metalla(di-π-methane) rearrangement due to the kinetic stability of the (N-enamino)ethoxycarbene products, while formation of pyrroles is not favored due to the presence of high energetic stationary structures in the α-cyclization pathway. For (β-imino)thiocarbene compounds 11, on the other hand, rearranged products are kinetically unstable, and α-cyclization reactions are strongly favored on thermodynamic grounds.

A novel set of polyphosphazenes are synthesized to produce three polymers with varying side group ratios for proton exchange membranes. The designed heterosubstituted polymers here are the rare examples of polyphosphazenes of this kind to serve as proton exchange membranes with optimized structural stability and high temperature ionic conductivity. High quality polyphosphazenes with narrow polydispersity and rather low Tg values were prepared. These poly(m‐tolyloxy‐co‐4‐pyridinoxy phosphazene)s are sulfonated under a range of conditions and characterized in order to investigate the synergetic effect of the heteroatom on the proton conductivity of the proton exchange membranes. The effect of sulfonation temperature and time on the fuel cell relevant properties is also investigated. Hydrolytically stable proton exchange membranes with high thermal and chemical stabilities are achieved. Additionally, resultant membranes exhibit proton conductivity, IEC and water uptake values comparable with commercial Nafion® membranes.