88224-06-0Relevant articles and documents
Chemical Synthesis of HMGA1a Proteins with Post-translational Modifications via Ser/Thr Ligation
Li, Tianlu,Liu, Heng,Li, Xuechen
, p. 5944 - 5947 (2016)
The first chemical synthesis of nuclear protein HMGA1a via Ser/Thr ligation is reported. Notably, Hmb (2-hydroxy-4-methoxybenzyl) exhibits crucial improvement of both the difficult coupling during solid phase peptide synthesis and the poor ligation encountered in protein synthesis. These efforts led to preparation of HMGA1a analogs with well-defined phosphorylation and methylation patterns (9 synthetic proteins in total), thus overcoming the heterogeneous and combinatory problems inherent to protein post-translational modifications (PTMs), and facilitating the study of the regulatory roles of such PTMs.
Low catalyst loading in ring-closing metathesis reactions
Kadyrov, Renat
supporting information, p. 1002 - 1012 (2013/02/23)
An efficient procedure is described for ring-closing metathesis reactions. A conversion of 95 % for diethyl diallylmalonate in dilute solution could be achieved within a few minutes, reaching TOF=4173min-1, with very low loading of commercially available Ru catalysts that contained unsaturated NHC ligands. In general, only 50 to 250ppm of the catalyst is required to achieve near-quantitative conversion into a broad variety of 5-16-membered heterocyclic compounds. The practicality of this procedure was illustrated in the synthesis of 5-8-membered N-tert-butoxycarbonyl (N-Boc)- and N-para-toluenesulfonyl (N-Ts)-protected cyclic amines and 9-16-membered lactones. The synthesis of macrocyclic proline-based lactams required slightly higher catalyst loadings. Along with monocyclic products, oligomeric byproducts, mostly cyclodimers, were isolated and characterized. Getting some closure: An efficient procedure is described for ring-closing metathesis reactions in which only 50 to 250ppm of catalyst is required to effect almost-quantitative conversion into a broad range of 5-16-membered heterocyclic compounds. The practicality of this procedure was illustrated in the synthesis of 5-8-membered N-protected cyclic amines, 9-16-membered lactones, and 11-16-membered proline-based lactams. Copyright
Protic acid immobilized on solid support as an extremely efficient recyclable catalyst system for a direct and atom economical esterification of carboxylic acids with alcohols
Chakraborti, Asit K.,Singh, Bavneet,Chankeshwara, Sunay V.,Patel, Alpesh R.
supporting information; experimental part, p. 5967 - 5974 (2009/12/24)
(Chemical Equation Presented) A convenient and clean procedure of esterification is reported by direct condensation of equimolar amounts of carboxylic acids with alcohols catalyzed by an easy to prepare catalyst system of perchloric acid immobilized on silica gel (HClO4-SiO2). The direct condensation of aryl, heteroaryl, styryl, aryl alkyl, alkyl, cycloalkyl, and long-chain aliphatic carboxylic acids with primary/secondary alkyl/cycloalkyl, allyl, propargyl, and long-chain aliphatic alcohols has been achieved to afford the corresponding esters in excellent yields. Chiral alcohol and N-t-Boc protected chiral amino acid also resulted in ester formation with the representative carboxylic acid or alcohol without competitive N-t-Boc deprotection and detrimental effect on the optical purity of the product demonstrating the mildness and chemoselectivity of the procedure. The esters of long-chain (>C10) acids and alcohols are obtained in high yields. The catalyst is recovered and recycled without significant loss of activity. The industrial application of the esterification process is demonstrated by the synthesis of prodrugs of ibuprofen and a few commercial flavoring agents. Other protic acids such as H2SO4, HBr, TfOH, HBF4, and TFA that were adsorbed on silica gel were less effective compared to HClO4-SiO2 following the order HClO4-SiO 2 ? H2SO4-SiO2 > HBr-SiO 2 > TfOH-SiO2 ? HBF4-SiO2 ≈ TFA-SiO2. When HClO4 was immobilized on other solid supports the catalytic efficiency followed the order HClO4-SiO 2 > HClO4-K10 > HClO4-Al 2O3 (neutral) > HClO4-Al2O 3 (acidic) > HClO4-Al2O3 (basic).
Synthetic approach toward the partial sequences of betaglycan in the linkage region on solid support and in solution phase
Tamura, Jun-Ichi,Yamaguchi, Akihiro,Tanaka, Junko,Nishimura, Yuko
, p. 61 - 82 (2008/02/09)
We have synthesized, for the first time, the partial sequence of the betaglycan composed of the tetraosyl hexapeptide, which was directly usable as a probe for enzymatic glycosyl transfer. Stepwise elongation afforded the corresponding tetraosyl trichloro
The palladium-catalyzed asymmetric α-allylations of carbonyl compounds with chiral allyl esters via enamines and imines
Hiroi,Abe,Suya,Sato,Koyama
, p. 203 - 213 (2007/10/02)
A novel and excellent method for asymmetric α-allylation of carbonyl compounds via their chiral enamines or imines bearing allyl esters has been developed. Readily available chiral allyl esters having chirality at the α- position of the ester carbonyl group, such as (S)-proline and other (S)-α- amino acid allyl esters, have been found to serve as good asymmetric allylating reagents in palladium-catalyzed reactions of the chiral enamines and imines derived from them. The use of (S)-proline or (S)-valine allyl esters as the amino parts in the enamines or imines provided the highest optical yields of the corresponding α-allyl carbonyl compounds. A mechanism for asymmetric induction is proposed based on the stereochemical results obtained.
