Hoge G.,Chirotech Technology Center
Sp2 | Year: 2014
As large and small pharma are looking for ever more innovative ways to develop small- and large-molecule therapeutics, custom manufacturing organisations are increasingly expected to adapt their approaches and rise to new challenges. This article reviews some recent trends in chiral technologies and discusses how scientists within CMOs are developing more effective and efficient chemistries.
Wilson M.R.,University of Manchester |
Sola J.,CSIC - Institute of Advanced Chemistry of Catalonia |
Carlone A.,Chirotech Technology Center |
Goldup S.M.,University of Southampton |
And 2 more authors.
Nature | Year: 2016
Molecular machines are among the most complex of all functional molecules and lie at the heart of nearly every biological process. A number of synthetic small-molecule machines have been developed, including molecular muscles, synthesizers, pumps, walkers, transporters and light-driven and electrically driven rotary motors. However, although biological molecular motors are powered by chemical gradients or the hydrolysis of adenosine triphosphate (ATP), so far there are no synthetic small-molecule motors that can operate autonomously using chemical energy (that is, the components move with net directionality as long as a chemical fuel is present). Here we describe a system in which a small molecular ring (macrocycle) is continuously transported directionally around a cyclic molecular track when powered by irreversible reactions of a chemical fuel, 9-fluorenylmethoxycarbonyl chloride. Key to the design is that the rate of reaction of this fuel with reactive sites on the cyclic track is faster when the macrocycle is far from the reactive site than when it is near to it. We find that a bulky pyridine-based catalyst promotes carbonate-forming reactions that ratchet the displacement of the macrocycle away from the reactive sites on the track. Under reaction conditions where both attachment and cleavage of the 9-fluorenylmethoxycarbonyl groups occur through different processes, and the cleavage reaction occurs at a rate independent of macrocycle location, net directional rotation of the molecular motor continues for as long as unreacted fuel remains. We anticipate that autonomous chemically fuelled molecular motors will find application as engines in molecular nanotechnology. © 2016 Macmillan Publishers Limited. All rights reserved.
Lovelock S.L.,University of Manchester |
Lloyd R.C.,Chirotech Technology Center |
Turner N.J.,University of Manchester
Angewandte Chemie - International Edition | Year: 2014
Phenylalanine ammonia lyases (PALs) belong to a family of 4-methylideneimidazole-5-one (MIO) cofactor dependent enzymes which are responsible for the conversion of L-phenylalanine into trans-cinnamic acid in eukaryotic and prokaryotic organisms. Under conditions of high ammonia concentration, this deamination reaction is reversible and hence there is considerable interest in the development of PALs as biocatalysts for the enantioselective synthesis of non-natural amino acids. Herein the discovery of a previously unobserved competing MIO-independent reaction pathway, which proceeds in a non-stereoselective manner and results in the generation of both L- and D-phenylalanine derivatives, is described. The mechanism of the MIO-independent pathway is explored through isotopic-labeling studies and mutagenesis of key active-site residues. The results obtained are consistent with amino acid deamination occurring by a stepwise E1cB elimination mechanism. All manner of things: A competing MIO-independent (MIO=4-methylideneimidazole-5-one) reaction pathway has been identified for phenylalanine ammonia lyases (PALs), which proceeds in a non-stereoselective manner, resulting in the generation of D-phenylalanine derivatives. The mechanism of D-amino acid formation is explored through isotopic-labeling studies and mutagenesis of key active-site residues. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Bernardi L.,University of Bologna |
Fochi M.,University of Bologna |
Carbone R.,University of Bologna |
Martinelli A.,University of Bologna |
And 6 more authors.
Chemistry - A European Journal | Year: 2015
In the context of a programme directed at the manufacture of telaprevir, eight possible approaches to its bicyclic α-amino acid core, based on organocatalytic enantioselective conjugate additions to cyclopent-1-enecarbaldehyde, were identified and preliminarily explored. Four reactions, delivering advanced intermediates en route to the target amino acid, were selected for a thorough optimisation. Three of this reactions involved iminium ion catalysis with a prolinol catalyst (addition of nitromethane, nitroacetate and acetamidomalonate) and one was based on a Cinchona-derived phase-transfer catalyst (addition of glycine imines). A careful choice of additives allowed lowering of the catalyst loading to 0.5 mol % in some cases. The preparation of intermediates that would give access to the core of telaprevir in good yields and enantioselectivities by exploiting readily available substrates and catalysts, highlights the potential of organocatalytic technology for a cost-effective preparation of pharmaceuticals. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Tin S.,University of St. Andrews |
Fanjul T.,Chirotech Technology Center |
Clarke M.L.,University of St. Andrews
Catalysis Science and Technology | Year: 2016
During studies on the enantioselective hydrogenation of unfunctionalised enamines, a very surprising switch in enantiopreference was observed; [((R,R)-Et-DUPHOS)-Rh(COD)]BF4 hydrogenates an enamine to give (R)-amine with up to 73% ee, but when iodine is added as a co-catalyst, the (S)-amine is formed with up to 61% ee. Mechanistic studies implicate a protonation-iminium ion reduction pathway. © 2016 The Royal Society of Chemistry.