4,12-Bis(2,2-dibromo­vinyl)[2.2]paracyclo­phane

In the title compound, C20H16Br4, both vinylic substituents were introduced by a Corey–Fuchs reaction using 4,12-diform­yl[2.2]paracyclo­phane as starting material. The title compound may be used as a valuable precursor for the synthesis of diethyn­yl[2.2]paracyclo­phane. The title mol­ecule is centrosymmetric with a crystallographic center of inversion between the centers of the two phenyl rings. A strong tilting is observed with an inter­planar angle between the best aromatic plane and the vinyl plane of 49.4 (5)°. No significant inter­molecular inter­actions are found in the crystal

(S)-1,2-Dimethyl-1,1,2-triphenyl-2-(4-piperidiniometh­yl)disilane chloride

The title compound, C26H34NSi2 +·Cl−, shows chirality at silicon. Because of its highly selective synthesis with an e.r. of >99:1 by means of a racemic resolution with mandelic acid, the free disilane is of great importance to the chemistry of highly enanti­omerically enriched lithio­silanes and their trapping products. N—H⋯Cl hydrogen bonding is present between the protonated nitro­gen atom of the piperidino group and the chloride counter-anion. The silicon–silicon distance as well as silicon–carbon and carbon–nitro­gen bond lengths are in the same ranges as in other quaternary, functionalized di- and tetra­silanes

(1R,2R)-N,N′-Dimethyl­cyclo­hexane-1,2-diamine

The molecule of the title compound, C8H18N2, possesses C 2 symmetry. Owing to its stereochemistry, it is used in the synthesis of chiral ligands and metal complexes for asymmetric synthesis. The cyclo­hexane ring shows a chair conformation with the amino groups in equatorial positions. Contrary to the literature, the title compound is not a liquid, but a crystalline solid at room temperature (293 K). The absolute configuration is assigned from the synthesis

Enantioselective synthesis of tricyclic amino acid derivatives based on a rigid 4-azatricyclo[5.2.1.02,6]decane skeleton

An enantioselective route to four tricyclic amino acids and N-tosylamides, composed of a central norbornane framework with a 2-endo,3-endo-annelated pyrrolidine ring and a 5-endo-C1 or -C2 side chain, has been developed. A key intermediate was the chiral, N-Boc-protected ketone (1R,2S,6S,7R)-4-azatricyclo[5.2.1.02,6]decan-8-one, available from inexpensive endo-carbic anhydride in five steps and 47% yield. The rigid scaffold makes these amino acid derivatives promising candidates for β-turn-inducing building blocks in peptidomimetics and for chiral auxiliaries in asymmetric organocatalysis