Employing modular polyketide synthase ketoreductases as biocatalysts in the preparative chemoenzymatic syntheses of diketide chiral building blocks
Chiral building blocks are valuable intermediates in the syntheses of natural products and pharmaceuticals. A scalable chemoenzymatic route to chiral diketides has been developed that includes the general synthesis of α-substituted, β-ketoacyl N-acetylcysteamine thioesters followed by a biocatalytic cycle in which a glucose-fueled NADPH-regeneration system drives reductions catalyzed by isolated modular polyketide synthase (PKS) ketoreductases (KRs). To identify KRs that operate as active, stereospecific biocatalysts, 11 isolated KRs were incubated with 5 diketides and their products were analyzed by chiral chromatography. KRs that naturally reduce small polyketide intermediates were the most active and stereospecific toward the panel of diketides. Several biocatalytic reactions were scaled up to yield more than 100 mg of product. These syntheses demonstrate the ability of PKS enzymes to economically and greenly generate diverse chiral building blocks on a preparative scale.
Piasecki, Shawn K.,Taylor, Clint A.,Detelich, Joshua F.,Liu, June,Zheng, Jianting,Komsoukaniants, Arkady,Siegel, Dionicio R.,Keatinge-Clay, Adrian T.
A useful modification of the Evans magnesium halide catalyzed anti-aldol reaction: Application to enolizable aldehydes
A practical protocol for use of the magnesium halide catalyzed anti-aldol reaction of an Evans N-acyloxazolidinone with enolizable aldehydes is reported. The yields of anti-aldol adducts for saturated or unsaturated and branched or unbranched aliphatic aldehydes are preparatively useful. Georg Thieme Verlag Stuttgart.
May, Aaron E.,Connell, Nathan T.,Dahlmann, Heidi A.,Hoye, Thomas R.
supporting information; experimental part
p. 1984 - 1986
(2010/10/03)
Preparation, modification, and evaluation of cruentaren a and analogues
An expeditious total synthesis of the highly cytotoxic F-ATPase inhibitor cruentaren A. (1) is described based on a. ring-closing alkyne metathesis (RCAM) reaction for the formation of the macrocylic ring. Other key transformations comprise a. C-acylation