@article {32712, title = {Selecting Chiral BINOL-Derived Phosphoric Acid Catalysts: General Model To Identify Steric Features Essential for Enantioselectivity}, journal = {Chemistry {\textendash} A European Journal}, volume = {23}, year = {2017}, pages = {14248-14260}, abstract = {

Abstract Choosing the optimal catalyst for a new transformation is challenging because the ideal molecular requirements of the catalyst for one reaction do not always simply translate to another. Large groups at the 3,3\′ positions of the binaphthol rings are important for efficient stereoinduction but if they are too large this can lead to unusual or poor results. By applying a quantitative steric assessment of the substituents at the 3,3\′ positions of the binaphthol ring, we have systematically studied the effect of modulating this group on enantioselectivity for a wide range of reactions involving imines, and verified this analysis using ONIOM calculations. We have shown that in most reactions, the stereochemical outcome depends on both proximal and remote sterics. Summarising detailed calculations into a simple qualitative model identifies and explains the steric features required for high selectivity. This model is consistent with seventy seven papers reporting reactions (over 1000 transformations in total), and provides a straightforward decision tree for selecting the best catalyst.

}, keywords = {ASYMMETRIC CATALYSIS, binaphthol, catalyst choice, chirality, phosphoric acid}, doi = {10.1002/chem.201702019}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/chem.201702019}, author = {Reid, Jolene P. and Goodman, Jonathan M.} } @article {1145, title = {Discrimination in the solid-state photodimerization of 1-methyl-5,6-diphenylpyrazin-2-one}, journal = {European Journal of Organic Chemistry}, number = {5}, year = {2005}, note = {ISI Document Delivery No.: 903LHTimes Cited: 5Cited Reference Count: 18}, month = {Feb}, pages = {847-853}, type = {Article}, abstract = {1-Methyl- and 1-ethyl-5,6-diphenylpyrazin-2-one crystallize in two modifications, one of which is light-stable and the other light-sensitive. The light-sensitive modification is known to undergo photodimerization in the solid state. This polymorph crystallizes in the monoclinic space group P2(1) with two crystallographically independent molecules in the asymmetric unit. The molecules are packed in stacks running parallel to the unique b axis. The two independent molecules are arranged alternately along the stack. In principle, there are two different pairs of molecules within a stack that can undergo photodimerization, and each should form a different enantiomer. A large crystal was irradiated and a solution of the product was separated by HPLC. The optical purity of the (+)-enantiomer sample was estimated to be greater than 90 \%. This finding indicates that only one of the two pairs undergoes photoreaction. The structure of a single crystal of the pyrazinone was elucidated by X-ray diffractometry before and after irradiation with a laser at a wavelength of 488 nm to 19 \% conversion. The results of the crystal-structure determinations provide additional evidence that only one of the two pairs of molecules undergoes photodimerization although there are no significant differences between the distances between the reacting centers. Furthermore, the latter results suggest that weak hydrogen bonds are a dominant factor that determines which of the two pairs is dimerized upon irradiation. ((C) Wiley-VCH Verlag GmbH \& Co. KGaA, 69451 Weinheim, Germany, 2005).}, keywords = {chirality, crystal structure, DIMERIZATION, enantioselectivity, PHOTOCHEMISTRY, SINGLE-CRYSTAL PHOTODIMERIZATION, solid-state reactions}, isbn = {1434-193X}, url = {://000227426900009}, author = {Kaftory, M. and Shteiman, V. and Lavy, T. and Scheffer, J. R. and Yang, M. and Enkelmann, V.} } @article {4954, title = {Nuclear magnetic resonance studies of helical dipyrromethene-zinc complexes}, journal = {Organic Letters}, volume = {2}, number = {9}, year = {2000}, note = {ISI Document Delivery No.: 309XRTimes Cited: 27Cited Reference Count: 16}, month = {May}, pages = {1315-1318}, type = {Article}, abstract = {Analysis of helical chirality within dinuclear dipyrromethene-Zn(II) complexes has been achieved with the use of H-1 NMR spectroscopy. The use of AgFOD and chiral lanthanide shift reagents gives fully resolved resonances attributable to two diastereomeric helical complexes.}, keywords = {chirality, LIGANDS, NMR, RESOLUTION, SHIFT-REAGENTS}, isbn = {1523-7060}, url = {://000086795200036}, author = {Thompson, A. and Dolphin, D.} } @article {3678, title = {The ionic auxiliary concept in solid state organic photochemistry}, journal = {Accounts of Chemical Research}, volume = {29}, number = {4}, year = {1996}, note = {ISI Document Delivery No.: UE738Times Cited: 121Cited Reference Count: 42}, month = {Apr}, pages = {203-209}, type = {Review}, keywords = {ASYMMETRIC INDUCTION, chirality, CRYSTAL, KETONES, PHOTOREARRANGEMENT, REACTIVITY, SALTS, SUPRAMOLECULAR PHOTOCHEMISTRY}, isbn = {0001-4842}, url = {://A1996UE73800006}, author = {Gamlin, J. N. and Jones, R. and Leibovitch, M. and Patrick, B. and Scheffer, J. R. and Trotter, J.} } @article {3678, title = {The ionic auxiliary concept in solid state organic photochemistry}, journal = {Accounts of Chemical Research}, volume = {29}, number = {4}, year = {1996}, note = {ISI Document Delivery No.: UE738Times Cited: 121Cited Reference Count: 42}, month = {Apr}, pages = {203-209}, type = {Review}, keywords = {ASYMMETRIC INDUCTION, chirality, CRYSTAL, KETONES, PHOTOREARRANGEMENT, REACTIVITY, SALTS, SUPRAMOLECULAR PHOTOCHEMISTRY}, isbn = {0001-4842}, url = {://A1996UE73800006}, author = {Gamlin, J. N. and Jones, R. and Leibovitch, M. and Patrick, B. and Scheffer, J. R. and Trotter, J.} } @article {3264, title = {THE ONE-STEP SYNTHESIS OF CHIRAL AMINO PHOSPHINO FERROCENES}, journal = {Journal of Organometallic Chemistry}, volume = {492}, number = {2}, year = {1995}, note = {ISI Document Delivery No.: QV350Times Cited: 10Cited Reference Count: 24}, month = {May}, pages = {157-164}, type = {Article}, abstract = {Reaction of the chiral lithium reagent-2-lithio-(alpha-N,N-dimethyl)aminoethylbenzene with 1,1{\textquoteright}-ferrocenediylphenylphosphine gives chiral aminophosphinoferrocenes that contain both chiral carbon and phosphorus centres. Treatment of the ferroceno-phane with 2-lithio-N,N-dimethylaminomethylferrocene followed by hydrolysis gives the product ferrocenyl 2-(dimethylaminomethylferrocenyl) phenylphosphine as a pair of diastereomers. The single crystal structures of compound 3a PdCl2 and compound 4. PdCl2.2CH(2)Cl(2) have been determined. The compounds, 2-(ferrocenylphenylphosphino)-1-(alpha-N, N{\textquoteright}-dimethylaminoethylbenzene)ferrocene, 5 and 1-[2-(alpha-N,N{\textquoteright}-dimethyraminoethylbenzene)phenylphospphino]-1{\textquoteright}-diphenyl phosphinoferrocene, 6a, have also been prepared by minor modifications of the methodology developed.}, keywords = {<1>FERROCENOPHANES, ASYMMETRIC-SYNTHESIS, CATALYST, chirality, crystal structure, FERROCENE, GRIGNARD, HALIDES, HYDROGENATION, iron, METAL-COMPLEXES, ORGANIC, palladium, PHOSPHORUS, PLANAR CHIRALITY, REAGENTS, SECONDARY}, isbn = {0022-328X}, url = {://A1995QV35000005}, author = {Butler, I. R. and Cullen, W. R. and Rettig, S. J. and White, A. S. C.} }