ChemInform Abstract: Asymmetric Trimethylsilylcyanation of Benzaldehyde Catalyzed by (Salen)Ti(IV) Complexes Derived from (R)‐ and/or (S)‐4‐Hydroxy‐5‐formyl[2.2]paracyclophane and Diamines.

Abstract

nitriles nitriles (benzene compounds) Q 0520 -125Asymmetric Trimethylsilylcyanation of Benzaldehyde Catalyzed by (Salen)Ti(IV) Complexes Derived from (R)-and/or (S)-4-Hydroxy-5-formyl[2.2]paracyclophane and Diamines.-A method for the catalytic, asymmetric preparation of cyanohydrins, versatile intermediates in organic synthesis, is presented using enantiomerically pure, cyclophane-based (salen)Ti(IV) complexes as catalysts. -(BELOKON, Y.; MOSCALENKO, M.; IKONNIKOV, N.; YASHKINA, L.; ANTONOV, D.; VORONTSOV, E.; ROZENBERG, V.; Tetrahedron

Interplay between σ Holes, Anion···H–C, and Cation−π Interactions in Dibromo[2,2]paracyclophane Complexes

“…Our results reveal that DBr [2,2]PCP can be a scavenger of trace cations and anions as it can react with trace Li + , Na + , K + , Be 2+ , Mg 2+ , Ca 2+ , F − , and Cl − to form more stable complexes via cation••• π and anion•••H−C interactions. The most remarkable result is that the anion−HC interactions in these complexes are found to be ∼10 kcal/mol stronger than the σ− holes.…”

“…Since its first synthesis by Brown and Farthing in 1949, 1 production and characterization of its derivatives of 1 have received great attention due to their potential use in various domains such as chiral catalysts and in the manufacture of various electronic and optical materials. 2,3 Henseler et al 4 investigated the molecular symmetry of 1 and found that it is unstable in D 2h symmetry and undergoes a symmetry breaking from D 2h to either D 2 or C 2h . The energy difference between C 2h and D 2 structures was computed to be only ∼0.6 kcal/mol.…”

“…The energy difference between C 2h and D 2 structures was computed to be only ∼0.6 kcal/mol. [2,2]Paracyclophane was reported to be a potential cornerstone of more elaborate compounds where donor and acceptor are made to interact through a sterically constrained π−π stack. It is a good example of a molecule with a forced "face to face" arrangement of aromatic rings.…”

“…23 According to Grabowski et al 24 the hydrogen bond interaction, σ−hole, and π−hole bonds are steered by the same mechanisms, such as electron charge transfer from the Lewis base to the Lewis acid unit. [2,2]Paracyclophane and its derivatives can form complexes with small ions involving different types of noncovalent interactions such as cation−π, CH−anion, and π−π interactions. The latter are reported to be at the root of many biochemical processes such as molecular recognition 25 and catalysis for reactions of small molecules.…”

“…31−33 In this context, we set out to investigate in the present various interactions such as the cation•••π, anion•••H−C interactions and σ−hole interactions between the dibromo-[2,2]paracyclophane (DBr[2,2]PCP) and alkali and alkaline earth metal cations (Li + , Na + , K + , Be 2+ , Mg 2+ , Ca 2+ ,) and halogen anions (F − , Cl − , and Br − ) and to find the most probable geometries of the complexes. A disubstitution of [2,2]paracyclophane can yield several isomers. This first requires a solution of the enumeration problem of isomers by figuring out the exact number of isomers of the dibromo substituted compounds.…”