Modern Aldol Methods for the Total Synthesis of Polyketides

Abstract

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Engineering of Enzymes for Selective Catalysis

“…Known as a cornerstone of modern organic chemistry, the reactions lead to the formation of a new carbon-carbon bond and up to two new stereogenic centers under mild conditions [63]. C-C bond forming reactions have been widely used in the stereo-controlled synthesis of natural products and bioactive small molecules using various metal enolates, as well as metal-complex-catalyzed and organocatalytic methods [65]. In addition, several enzyme classes have been shown to catalyze C-C bond forming reactions, including the transketolases, oxynitrilases, and aldolases [63], as well as other thiamine pyrophosphate (TPP) independent enzymes [66].…”

Enantioselective Total Synthesis of (−)‐Doliculide Using Catalytic Asymmetric Hydrogenations

“…Over the past decades, tremendous efforts have been made to the syntheses of polyketides because of their various pharmacological activities. [3][4][5] Doliculide is a novel 16membered polyketide isolated from Japanese sea hare Dolabella auricularia. It exhibited potent in vitro antiproliferative activity against the human leukemia cell line HeLa-S3 with an IC 50 value of 1 ng/mL.…”

Diastereoselective Hydroxyethylation of β‐Hydroxyketones: A Reformatsky Cyclization‐Lactone Reduction Cascade Mediated by SmI2−H2O

“…The 1,3,5‐triol motif is an important motif found in a number of biologically active natural products including important polyketides ( Scheme ,a ) . The motif is most often constructed by diastereoselective ketone reduction . Samarium diiodide ( Kagan ’s reagent, SmI 2 ) is well‐known for its ability to form carbon−carbon bonds, with high diastereoselectivity, particularly when couplings are carried out in an intramolecular sense.…”

“…[1][2][3][4][5] The motif is most often constructed by diastereoselective ketone reduction. [6][7][8][9][10][11][12] Samarium diiodide (Kagan's reagent, SmI 2 ) is well-known for its ability to form carbonÀ carbon bonds, with high diastereoselectivity, [13][14][15] particularly when couplings are carried out in an intramolecular sense. Recently, our group has expanded the synthetic reach of the reagent by developing chemistry involving radicals generated from the carbonyl groups of carboxylic acid derivatives.…”