214334-06-2

Upstream product

• 18421-15-3 (±)-N-((1R,2R)-2-hydroxycyclohexyl)acetamide 
• 108-24-7 acetic anhydride 
• 114828-08-9 2,4,6-tri-O-benzyl-myo-inositol 
• 1499-21-4 Diphenylphosphinic chloride 

Relevant academic research and scientific papers

Outer-Sphere Control for Divergent Multicatalysis with Common Catalytic Moieties

We herein report two examples of one-pot, simultaneous reactions, mediated by multiple, orthogonal catalysts with the same catalytic motif. First, BINOL-derived chiral phosphoric acids (CPA) and phosphothreonine (pThr)-embedded peptides were found to be matched for two different steps in double reductions of bisquinolines. Next, two -methylhistidine (Pmh)-containing peptides catalyzed enantio- and chemoselective acylations and phosphorylations of multiple substrates in one pot. The selectivity exhibited by common reactive moieties is adjusted solely by the appended chiral scaffold through outer-sphere interactions.

Backbone modification of β-hairpin-forming tetrapeptides in asymmetric acyl transfer reactions

Synthetic oligopeptides as mimics of enzymes have been increasingly exploited as catalysts for asymmetric reactions, but highly effective oligopeptide catalysts with relatively low molecular weight are still in great demand. In this paper, we showed the conformational engineering of the β-hairpin-forming tetrapeptide 4 which was first reported by Miller's group as the catalyst for the asymmetric acyl transfer reaction of trans-2-(N-acetylamino)cyclohexan-1-ol (krel = 28). Through our backbone modification strategy, thioamide and sulfonamide as the isosteres of amide were introduced in the β-hairpin secondary structure. The thioxo peptides also adopt β-hairpin conformations as the oxopeptide supported by the combined use of NMR, IR, and X-ray techniques. Thioxo tetrapeptide 14 formed a more constrained β-hairpin conformation and therefore delivered much higher enantioselectivity (krel = 109) in the same reaction. Moreover, the examination of the conformational changes of tetrapeptide 8 upon the protonation of the Nπ-methylhistidine moiety provided evidence to explain the variation of its catalytic efficiency in the asymmetric acyl-transfer reaction.

Fluorescence-based screening of asymmetric acylation catalysts through parallel enantiomer analysis. Identification of a catalyst for tertiary alcohol resolution

A technique for high-throughput screening of kinetic resolution catalysts is reported. The method relies on carrying simultaneous kinetic resolutions in a multiwell plate format wherein each well contains a unique catalyst and a small amount of a pH-activated fluorescent sensor (3). By conducting experiments such that each catalyst is evaluated in parallel in the presence of each isolated enantiomer, an indication of catalyst activity is obtained on a per enantiomer basis. Catalysts that are highly active for one enantiomer but modestly active for another are then reevaluated in conventional kinetic resolutions. From these screens, a highly selective krel = 46) pentapeptide (4) was obtained for a model secondary alcohol (1). In addition, peptide 10 was found to afford excellent selectivities (krel > 20) for a number of alcohol substrates (9a-9f) in the traditionally challenging tertiary class.

Asymmetric acylation reactions catalyzed by conformationally biased octapeptides

Octapeptides capable of adopting β-hairpin conformations have been found to function as efficient catalysts for the kinetic resolution of certain racemic secondary alcohols. Parallel solid phase synthesis of a series of peptides with the common feature of the D-Pro-Gly sequence at the turn region (i+3 to i+4) was carried out to yield a family of octapeptide catalysts. The peptides were then screened for their efficiency in a number of enantioselective acylation reactions. (C) 2000 Elsevier Science Ltd.