112083-64-4Relevant articles and documents
A Concise Stereoselective Total Synthesis of Methoxyl Citreochlorols and Their Structural Revisions
Sunnapu, Ranganayakulu,Rajendar, Goreti
, p. 1637 - 1642 (2021/03/15)
A concise, stereoselective and protecting group free approaches for the total synthesis of (?)-(2S,4R)- and (+)-(2R,4S)-3′-methoxyl citreochlorols and their stereoisomers are demonstrated. All four stereoisomers were synthesized to establish the absolute stereochemistry of the reported structures and the structures were revised accordingly. The approach involves chelation controlled regioselective reduction of a diester, silyl iodide promoted ring-opening iodo esterification of lactones, highly chemo- and regioselective ring-opening of an epoxy ester, dichloromethylation of a carboxyl group, and syn- and anti-selective reduction of the resulted β-hydroxy ketone as key steps.
Biocatalytic and Structural Properties of a Highly Engineered Halohydrin Dehalogenase
Schallmey, Marcus,Floor, Robert J.,Hauer, Bernhard,Breuer, Michael,Jekel, Peter A.,Wijma, Hein J.,Dijkstra, Bauke W.,Janssen, Dick B.
, p. 870 - 881 (2013/07/25)
Two highly engineered halohydrin dehalogenase variants were characterized in terms of their performance in dehalogenation and epoxide cyanolysis reactions. Both enzyme variants outperformed the wild-type enzyme in the cyanolysis of ethyl (S)-3,4-epoxybutyrate, a conversion yielding ethyl (R)-4-cyano-3-hydroxybutyrate, an important chiral building block for statin synthesis. One of the enzyme variants, HheC2360, displayed catalytic rates for this cyanolysis reaction enhanced up to tenfold. Furthermore, the enantioselectivity of this variant was the opposite of that of the wild-type enzyme, both for dehalogenation and for cyanolysis reactions. The 37-fold mutant HheC2360 showed an increase in thermal stability of 8°C relative to the wild-type enzyme. Crystal structures of this enzyme were elucidated with chloride and ethyl (S)-3,4-epoxybutyrate or with ethyl (R)-4-cyano-3-hydroxybutyrate bound in the active site. The observed increase in temperature stability was explained in terms of a substantial increase in buried surface area relative to the wild-type HheC, together with enhanced interfacial interactions between the subunits that form the tetramer. The structures also revealed that the substrate binding pocket was modified both by substitutions and by backbone movements in loops surrounding the active site. The observed changes in the mutant structures are partly governed by coupled mutations, some of which are necessary to remove steric clashes or to allow backbone movements to occur. The importance of interactions between substitutions suggests that efficient directed evolution strategies should allow for compensating and synergistic mutations during library design.
Lobatamide C: Total synthesis, stereochemical assignment, preparation of simplified analogues, and V-ATPase inhibition studies
Shen, Ruichao,Lin, Cheng Ting,Bowman, Emma Jean,Bowman, Barry J.,Porco Jr., John A.
, p. 7889 - 7901 (2007/10/03)
The total synthesis and stereochemical assignment of the potent antitumor macrolide lobatamide C, as well as synthesis of simplified lobatamide analogues, is reported. Cu(I)-mediated enamide formation methodology has been developed to prepare the highly unsaturated enamide side chain of the natural product and analogues. A key fragment coupling employs base-mediated esterification of a β-hydroxy acid and a salicylate cyanomethyl ester. Three additional stereoisomers of lobatamide C have been prepared using related synthetic routes. The stereochemistry at C8, C11, and C15 of lobatamide C was assigned by comparison of stereoisomers and X-ray analysis of a crystalline derivative. Synthetic lobatamide C, stereoisomers, and simplified analogues have been evaluated for inhibition of bovine chromaffin granule membrane V-ATPase. The salicylate phenol, enamide NH, and ortho-substitution of the salicylate ester have been shown to be important for V-ATPase inhibitory activity.
