15019-27-9Relevant academic research and scientific papers
A crystalline, internally-coordinated chloroborane for asymmetric hydroboration
von Dollen, Breanna,Wood, John L.,Savage, Quentin R.,Jones, Andrew J.,Garner, Charles M.
supporting information, (2022/02/01)
Asymmetric hydroboration is an important method in the preparation of enantiomerically-enriched compounds that are necessary in many areas of chemistry. Here is reported the preparation of a unique chiral chloroborane-internal ether complex and its applic
Copper-catalyzed enantioselective hydroboration of unactivated 1, 1-disubstituted alkenes
Jang, Won Jun,Song, Seung Min,Moon, Jong Hun,Lee, Jin Yong,Yun, Jaesook
supporting information, p. 13660 - 13663 (2017/11/07)
We report an efficient and highly enantioselective hydroboration of aliphatic 1, 1-disubstituted alkenes with pinacolborane using a phosphine-Cu catalyst. The method allows facile preparation of enantiomerically enriched β-chiral alkyl pinacolboronates from a range of 1, 1-disubstituted alkenes with high enantioselectivity up to 99% ee. Unprecedented enantiodiscrimination between the geminal alkyl substituents was observed with functional group compatibility in the hydroboration. Furthermore, a catalyst loading as low as 1 mol % furnished the desired product without a decrease in yield or selectivity, demonstrating its efficiency in gram scale synthesis.
Rational Design of Thermodynamic and Kinetic Binding Profiles by Optimizing Surface Water Networks Coating Protein-Bound Ligands
Krimmer, Stefan G.,Cramer, Jonathan,Betz, Michael,Fridh, Veronica,Karlsson, Robert,Heine, Andreas,Klebe, Gerhard
, p. 10530 - 10548 (2016/12/16)
A previously studied congeneric series of thermolysin inhibitors addressing the solvent-accessible S2′ pocket with different hydrophobic substituents showed modulations of the surface water layers coating the protein-bound inhibitors. Increasing stabilization of water molecules resulted in an enthalpically more favorable binding signature, overall enhancing affinity. Based on this observation, we optimized the series by designing tailored P2′ substituents to improve and further stabilize the surface water network. MD simulations were applied to predict the putative water pattern around the bound ligands. Subsequently, the inhibitors were synthesized and characterized by high-resolution crystallography, microcalorimetry, and surface plasmon resonance. One of the designed inhibitors established the most pronounced water network of all inhibitors tested so far, composed of several fused water polygons, and showed 50-fold affinity enhancement with respect to the original methylated parent ligand. Notably, the inhibitor forming the most perfect water network also showed significantly prolonged residence time compared to the other tested inhibitors.
Sensing remote chirality: Stereochemical determination of β-, γ-, and δ-chiral carboxylic acids
Tanasova, Marina,Anyika, Mercy,Borhan, Babak
, p. 4274 - 4278 (2015/04/14)
Determining the absolute stereochemisty of small molecules bearing remote nonfunctionalizable stereocenters is a challenging task. Presented is a solution in which appropriately substituted bis(porphyrin) tweezers are used. Complexation of a suitably derivatized β-, γ-, or δ-chiral carboxylic acid to the tweezer induces a predictable helicity of the bis(porphyrin), which is detected as a bisignate Cotton Effect (ECCD). The sign of the ECCD curve is correlated with the absolute stereochemistry of the substrate based on the derived working mnemonics in a predictable manner.
Synthetic routes to campesterol and dihydrobrassicasterol: A first reported synthesis of the key phytosterol dihydrobrassicasterol
O'Connell,O'Callaghan,O'Brien,Maguire,McCarthy
experimental part, p. 4995 - 5004 (2012/08/28)
Phytosterols are increasingly used as health supplements in functional foods and are associated with having both positive and negative effects on health. Given this disparity, an investigation of their full individual biological profile is imperative in order to assure food safety. This paper describes the de novo synthesis of pure phytosterols in multigram scale and we report the first synthesis of the key phytosterol dihydrobrassicasterol along with a comparison of routes to campesterol. A detailed spectroscopic analysis is included with full assignment of the 13C NMR spectroscopic data of both compounds, mixtures and their precursors leading to the potential use of NMR spectroscopy as a tool for analysis of these sterol mixtures.
9-Borabicyclo[3.3.2]decanes and the asymmetric hydroboration of 1,1-disubstituted alkenes
Gonzalez, Ana Z.,Roman, Jose G.,Gonzalez, Eduvigis,Martinez, Judith,Medina, Jesus R.,Matos, Karl,Soderquist, John A.
supporting information; experimental part, p. 9218 - 9219 (2009/02/02)
The syntheses of the optically pure asymmetric hydroborating agents 1 (a, R = Ph; b, R = TMS) in both enantiomeric forms are reported. These reagents are effective for the hydroboration of cis-, trans- and trisubstituted alkenes. More significantly, they exhibit unprecedented levels of selectivity in the asymmetric hydroboration of 1,1-disubstituted alkenes (28-92% ee), a previously unanswered challenge in the nearly 50 year history of this reagent-controlled process. For example, the hydroboration of α-methylstyrene with 1a produces the corresponding alcohol 6f in 78% ee (cf., Ipc2BH, 5% ee). Suzuki coupling of the intermediate adducts 5 produces the nonracemic products 7 very effectively (50-84%) without loss of optical purity. Copyright
Enantioselective synthesis of 2-substituted alcohols using (+)-(1S,2S)-pseudoephedrine as chiral auxiliary
Tietze, Lutz F.,Raith, Christian,Brazel, C. Christian,Hoelsken, Soeren,Magull, Joerg
, p. 229 - 236 (2008/12/20)
An improved method for the selective synthesis of enantiopure 2-substituted alcohols is described. Highly diastereoselective alkylation of pseudoephedrine-derived amides and subsequent oxidation of the hydroxyl group in the amide side chain, leads to oxoamides. These oxoamides can be purified by crystallization or preparative HPLC to obtain diastereomeric ratios of >99:1. The following reductive cleavage of the modified auxiliary allows the epimerization-free formation of enantiopure 2-substituted alcohols with up to 99.9% ee. Georg Thieme Verlag Stuttgart.
Enantioselective Synthesis of Useful Chiral Precursors, Unsymmetrical Propane-1,3-diol Derivatives, from Malonic acid
Ihara, Masataka,Takahashi, Masanobu,Taniguchi, Nobuaki,Fukumoto, Keiichiro,Kametani, Tetsuji
, p. 619 - 620 (2007/10/02)
Syntheses of chiral synthons via monosubstituted malonic chiral half esters were studied and chiral 3-silyloxy propanols were enantioselectively synthesised.
