Stereoselective Synthesis of Tetrasubstituted Olefins

The stereoselective synthesis of tetrasubstituted olefins represents a central challenge in modern organic chemistry, owing to the high steric congestion around the double bond and the need to control both geometry and substitution pattern. These fully substituted alkenes feature four distinct groups bonded to the carbon–carbon double bond, a motif found in advanced materials, pharmaceuticals and agrochemicals. Precise control of E/Z geometry impacts molecular shape, biological activity and material properties, while regioselectivity governs the arrangement of substituents. Recent advances have leveraged innovative catalysts, flow microreactor technologies and metal-free protocols to overcome energy barriers and expand functional-group tolerance. Strategic combination of borylmetallation, olefination and cross-coupling has enabled access to diverse tetrasubstituted frameworks under mild conditions, driving forward applications in drug development and optoelectronic materials.

Research from Nature Portfolio

Recent studies have demonstrated a flow microreactor approach to reductive syn-borylmetallation of arylacetylenes, generating β-borylalkenyllithium and β-borylalkenylsodium intermediates with exceptional stereo- and regiocontrol. The rapid mixing of alkyne and alkoxypinacolborane with alkali metal arenide suppresses unwanted diboration and enables subsequent trapping with electrophiles to furnish a variety of differently tetrasubstituted alkenes in high yield. This platform has been applied to the construction of complex oxaboroles, highlighting its versatility in multisubstituted olefin assembly.

Complementing this, a metal-free sulfur-mediated olefination of N-tosylhydrazones has emerged as an efficient route to tetraarylethylenes. Using elemental sulfur and base, diazo and thiirane intermediates converge to form tetraaryl alkenes under benign conditions. A modified protocol further extends to selective cross-coupling of different alkylidene fragments, enabling broader access to tri- and tetrasubstituted olefin scaffolds without reliance on transition metals.

Stereoselective Synthesis of Tetrasubstituted Olefins publication trend

The graph below shows the total number of articles in stereoselective synthesis of tetrasubstituted olefins across all publications each year (not limited to Nature Index journals).

Technical terms

Stereoselective synthesis: A process that selectively produces one stereoisomer over others in a chemical reaction.

Tetrasubstituted olefins: Alkenes featuring four substituents attached to the carbon–carbon double bond.

Regioselectivity: Preference for chemical bond formation at one position over other possible positions in a substrate.

Syn-borylmetallation: Concurrent addition of a boryl group and a metal species across a multiple bond in the same relative orientation.

Cross-coupling reaction: Catalytic formation of carbon–carbon bonds by coupling two different organic fragments.

Olefin metathesis: Redistribution of alkene fragments via catalyst-mediated exchange of substituents.

References

1. Reductive stereo- and regiocontrolled boryllithiation and borylsodiation of arylacetylenes using flow microreactors. Nature Synthesis (2023).
2. Synthesis of highly substituted alkenes by sulfur-mediated olefination of N-tosylhydrazones. Communications Chemistry (2023).
3. Synthesis of Tetrasubstituted Alkenes via Metathesis. Molecules (2012).
4. Palladium-Catalyzed Cross-Coupling Reactions of Borylated Alkenes for the Stereoselective Synthesis of Tetrasubstituted Double Bond. Organics (2022).
5. Palladium-catalyzed three-component synthesis of phosphine-containing tetrasubstituted acyclic unsymmetric all-carbon olefins. Cell Reports Physical Science (2021).