Application of Vinyl Nucleophiles in Matteson Homologations

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.

Stereospecific and Regioselective Synthesis of E-Allylic Alcohols through Reductive Cross Coupling of Terminal Alkynes

We have developed a convergent method for the synthesis of allylic alcohols that involves a reductive coupling of terminal alkynes with α-chloro boronic esters. The new method affords allylic alcohols with excellent regioselectivity (anti-Markovnikov) and an E/Z ratio greater than 200:1. The reaction can be performed in the presence of a wide range of functional groups and has a substrate scope that complements the stoichiometric alkenylation of α-chloro boronic esters performed using alkenyl lithium and Grignard reagents. The transformation is stereospecific and allows for the robust and highly selective synthesis of chiral allylic alcohols. Our studies support a mechanism that involves hydrocupration of the alkyne and cross-coupling of the alkenyl copper intermediate with α-chloro boronic esters. Experimental evidence excludes a radical mechanism of the cross-coupling step and is consistent with the formation of a boron-ate intermediate and a 1,2-metalate shift.

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.

A unified strategy for the synthesis of aldohexoses by boronate assisted assembly of CH2X2 derived C1-building blocks

A synthetic strategy for all aldohexoses with individually addressable protecting groups from dihalomethane C1-units is reported. The underlying synthesis of C6-sugar alcohols relies on three consecutive Matteson sequences, vinylation and bishydroxylation. Erythro and threo isomers have been realized for every glycol motif by strategic variation of the sequence.

Stereodivergent Zweifel Olefination and its Mechanistic Dichotomy

Stereoselective Zweifel olefination using boronate complexes carrying two different reactive π-systems was achieved to synthesize vinyl heteroarenes and conjugated 1,3-dienes in good yield and up to 100 % stereoselectivity, which remains unexplored until now. Most importantly, we report the unprecedented formation of E vs. Z-vinyl heteroarenes for different heteroarenes under identical conditions. Density functional theory (DFT) investigations unveil the mechanistic dichotomy between olefin and heteroarene activation followed by 1,2-migration, leading to E or Z-vinyl heteroarenes respectively. We also report a previously unknown reversal of stereoselectivity by using 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as an electrophile. The Zweifel olefination using a boronate complex that carries two different olefins was previously unexplored due to significant challenges associated with the site-selective activation of olefins. We have solved this problem and reported the site-selective activation of olefins for the stereoselective synthesis of 1,3-dienes.

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.