Dibutylsilylene Derivatives of Tartaric Acid

Abstract

Crystals of the bis(tert‐butyl)silylene (DTBS) derivatives of the tartaric acids were synthesized from D‐, L‐, rac‐, and meso‐tartaric acid and DTBS bis(trifluoromethanesulfonate): two polymorphs of Si2tBu4(L‐Tart1,2;3,4H–4) (L‐1a and L‐1b), the mirror image of the denser modification (D‐1b) as well as the racemate (2), and the meso analogue Si2tBu4(meso‐Tart1,3;2,4H–4) (3). The structures were determined by single‐crystal X‐ray diffraction. The threo‐configured D‐ and L‐ (and rac‐) tartrates were coordinated by two tBu2Si units forming five‐membered chelate rings, whereas the erythro‐configured meso‐tartrate formed six‐membered chelate rings. The new compounds were analyzed by NMR techniques, including 29Si NMR spectroscopy, and single‐crystal X‐ray crystallography.

Cobalt-Catalyzed Intramolecular Silylperoxidation of Unsaturated Diisopropylsilyl Ethers

“…This product, however, was not stable to purification by column chromatography . Its formation was suggested by 29 Si NMR spectroscopy, which showed that not only had the chemical shift of diisopropylsilylene acetal 26 changed compared to that of the starting material ( 25 ), but also that this new chemical shift was within the range of other five-membered ring silylene acetals (Scheme , eq 6). , These observations were confirmed by demonstrating that treatment of diisopropylsilylene acetal 26 with tetrabutylammonium fluoride yielded the corresponding 1,2-diol ( 27 ) in 19% yield over three steps (Scheme , eq 6).…”

Chiral Supramolecular Microporous Thio-Oxomolybdenum(V) Tartrates for the Selective Adsorptions of Gases

“…Hexavalent molybdenum salts and tartrates tend to form binuclear species in solutions, which refer to some reported peroxo Mo(VI) tartrates like K 24 and some other similar metal tartrates. 29,30 Thus, compound 2 will generate the possible binuclear intermediate [Mo VI 2 O 6 (tart)] 4− first, followed by the reduction of molybdenum and subsequent substitution of oxygen with sulfur, and finally coupled with free protonated H 2 2-mim's through hydrogen bonds for the formation of a tetranuclear structure. However, according to the structural descriptions of D-1/L-1 below, the most reasonable transition should be the hexanuclear [Mo VI 6 O 12 (μ 2 -O) 3 (Htart) 3 ] 3− skeleton.…”

Approximate Symmetry in Low-Symmetry Space Groups: P2 and C2

“…(a) View along b of the C 2, Z ′ = 2 structure KIVSEP01, in which the two independent molecules are segregated in layers (100). (b) The two layers (100).…”