A Straightforward Synthesis of Polyketides via Ester Dienolate Matteson Homologation

Chemical Ligation-Mediated Total Synthesis of Corramycin

The ligation-mediated total synthesis of corramycin, a myxobacterial natural product of the strain Corallococcus coralloides, is presented. The synthetic strategy included using two consecutive chemical ligations for a modular and efficient preparation. Finally, the synthesis employed a Ser/Thr ligation (STL) at a new ligation site combined with classical fragment coupling. This study provides the total synthesis of corramycin and enhances the preparative toolbox of STL in organic synthesis.

Synthesis and Late-Stage Modification of (-)-Doliculide Derivatives Using Matteson's Homologation Approach

(-)-Doliculide, a marine cyclodepsipeptide derived from the Japanese sea hare, Dolabella auricularia, exhibits potent cytotoxic properties, sparking interest in the field of synthetic chemistry. It is comprised of a peptide segment and a polyketide moiety, rendering it amenable to Matteson's homologation methodology. This technique facilitates the diversification of the distinctive polyketide side chain, thereby permitting the introduction of functional groups in late stages for modifications of the derived compounds and studies on structure-activity relationships.

Matteson Homologation-Based Total Synthesis of Meliponamycin A

The first total synthesis of meliponamycin A, an antimicrobial cyclodepsipeptide isolated from Streptomyces, is reported. Two key building blocks, the substituted tetrahydropyranyl side chain and an azido analogue of protected β-hydroxyleucine, were constructed via iterative Matteson homologations. A fragment coupling of a tetrapeptide, a depsidipeptide building block, macrocyclization, Staudinger reduction, and N-acylation are further steps in the synthesis.

Stereoselective Synthesis of Secondary and Tertiary Boronic Esters via Matteson Homologation

Matteson homologations of chiral boronic esters with lithium dichlorocarbenoids and various nucleophiles proved to be a useful method for the synthesis of functionalized polyketides in a highly stereoselective fashion. Via repeated homologation steps, only 1,2-anti- and 1,3-syn-configured products were obtained. Homologation with substituted carbenoids followed by reaction with carbon nucleophiles resulted in configurationally inverted products and tertiary boronic esters in a highly stereoselective fashion. This approach significantly expands the potential of the Matteson reaction.

Isomerization-Free Matteson Homologations of Substituted Allylboronic Esters

Substituted allyl derivatives with an internal double bond can be homologated under standard conditions via a 1,2-shift, whereas allylboronic esters with terminal double bonds can also be homologated via a SN' reaction. This allyl isomerization is catalyzed by ZnCl2 and can be suppressed by omitting ZnCl2 during the formation of α-chloroboronic ester. However, in the second step with Grignard reagents, ZnCl2 was added to suppress side reactions of the product formed.

Total synthesis and biological evaluation of histone deacetylase inhibitor WF-3161

A novel synthesis of the naturally occurring HDAC inhibitor WF-3161 is described. Key steps include the Matteson homologation to generate the stereogenic centres in the side chain, and Pd-catalysed C-H functionalisation to connect the side chain to the peptide backbone. WF-3161 was found to be highly selective for HDAC1, whereas no activity was observed towards HDAC6. High activity was also found against the cancer cell line HL-60.

Stereoselective Synthesis of a Protected Side Chain of Callipeltin A

Matteson homologations of chiral boronic esters proved to be an excellent tool for the synthesis of highly functionalized amino and hydroxy acid residues. This method provides straightforward stereoselective access to the side chain of callipeltin A, a natural marine product with interesting biological activities. Furthermore, this protocol should allow for variations in the substitution pattern in future SAR studies, simply by choosing suitable nucleophiles during the homologation steps.

Application of Vinyl Nucleophiles in Matteson Homologations

The Matteson homologation with vinyl nucleophiles was found to be a versatile tool for the synthesis of highly substituted and functionalized allyl boronic esters. High yields and stereoselectivities are obtained with sterically demanding alkyl boronic esters and/or Grignard reagents. With the application of such vinyl Matteson homologations, the polyketide fragment of lagunamide B is synthesized.

Stereoselective Synthesis of a Protected Side Chain of Meliponamycin A

The Matteson homologation was found to be a versatile tool for the construction of the linear polyketide side chain of meliponamycin and related compounds in only four steps. The ester dienolate version of this reaction allowed the introduction of the unsaturated ester moiety in a highly stereoselective fashion. Boronate oxidation/deoxygenation and Sharpless dihydroxylation are additional key steps in the stereoselective construction of this highly functionalized tetrahydropyran ring system, which is characteristic of this substance class.

Application of Allylzinc Reagents as Nucleophiles in Matteson Homologations

Allylzinc reagents are versatile nucleophiles that can be used in Matteson homologations. The linear substitution products are formed almost exclusively, and excellent E selectivities are observed in reactions of reagents with sterically demanding or aryl substituents on the double bond. The allylated boronic esters obtained can be converted into trifluoroborates or subjected to further homologations. Ozonolysis of the double bond provides aldehydes or ketones, and therefore, allylzinc reagents are useful acetaldehyde or ketone enolate equivalents.

Total synthesis of apratoxin A and B using Matteson's homologation approach

Apratoxin A and B, two members of an interesting class of marine cyclodepsipeptides are synthesized in a straightforward manner via Matteson homologation. Starting from a chiral boronic ester, the polyketide fragment of the apratoxins was obtained via five successive homologation steps in an overall yield of 27% and very good diastereoselectivity. This approach is highly flexible and should allow modification also of this part of the natural products, while previous modifications have been carried out mainly in the peptide fragment.