boron and 3-hydroxybutanal

The aldol reaction is one of the most important methods for the stereoselective construction of polyketide natural products, not only for nature but also for synthetic chemistry. The tremendous development in the field of aldol additions during the last 30 years has led to more and more total syntheses of complicated natural products. This Review illustrates by means of selected syntheses of natural products the new variants of the aldol addition. This includes aldol additions with various metal enolates, as well as metal-complex-catalyzed, organocatalytic, and biocatalytic methods.

Topics: Aldehydes; Anti-Bacterial Agents; Boron; Catalysis; Erythromycin; Macrolides; Molecular Structure; Organometallic Compounds

The total syntheses of aflastatin A and its C3-C48 degradation fragment (

Topics: Aldehydes; Boron; Molecular Structure; Pyrrolidinones; Stereoisomerism

A catalytic carboxylic acid-selective aldol reaction with trifluoromethyl ketones was developed. Reversible and selective covalent bond formation between a boron catalyst and a carboxylic acid is key to realizing the unprecedented catalytic aldol reaction of simple carboxylic acids. The reaction proceeded chemoselectively at the α-position of carboxylic acid even in the presence of ketone, ester, or amide functional groups in the donor substrates. The chemoselectivity is beneficial for late-stage derivatizations of biologically relevant compounds, as demonstrated by the conversion of indomethacin and triacetylcholic acid.

Topics: Aldehydes; Boron; Carboxylic Acids; Catalysis; Esters; Ketones; Molecular Structure; Structure-Activity Relationship

A practical and convergent asymmetric route to calcium atorvastatin (1) is reported. The synthesis of calcium atorvastatin (1) was performed using the remote 1,5-anti asymmetric induction in the boron-mediated aldol reaction of β-alkoxy methylketone (4) with pyrrolic aldehyde (3) as a key step. Calcium atorvastatin was obtained from aldehyde (3) after 6 steps, with a 41% overall yield.

Topics: Aldehydes; Atorvastatin; Boron; Chemistry Techniques, Analytical; Molecular Structure

In 1976 Mukaiyama published a paper that was to make a major impact on the development of the aldol reaction in the future. Mild enolate formation by treatment of a ketone with dibutylboron triflate in the presence of a tertiary amine generates a relatively stable boron enolate, which can subsequently react with an aldehyde to give the cross-aldol product in good yields. This reaction has become a reliable tool for the practicing synthetic chemist. Nearly 10000 polyketides are known, and of these about 600 contain the tripropionate unit with a stereotetrad, four contiguous stereocenters with alternating methyl and hydroxyl substituents in the main chain. The versatility of the boron enolate aldol reaction is showcased with selected applications in the synthesis of these structural motifs.

Topics: Aldehydes; Boron; Polyketides; Stereoisomerism

A novel domino process for 1,3-anti diol synthesis by the union of a methyl ketone with an aldehyde is described. The operationally simple procedure is based on an Ipc-boron-aldol coupling and subsequent Ipc-mediated reduction of the intermediate β-hydroxy-ketone. The sequence proceeds with excellent anti-selectivities and enables the rapid construction of complex polyketide fragments.

Topics: Alcohols; Aldehydes; Boron; Catalysis; Ketones; Molecular Structure; Stereoisomerism