Asymmetric Synthesis Techniques for Natural Products

Asymmetric synthesis lies at the heart of modern natural product chemistry, enabling the construction of complex bioactive molecules in enantiomerically pure form. Central strategies encompass chiral catalysis, auxiliary-mediated approaches and tandem cyclisation sequences, each designed to control stereochemical outcomes during bond-forming events. Transition-metal catalysts bearing chiral ligands have been widely adopted for enantioselective cycloadditions and cross-couplings, while Brønsted acids and organocatalysts offer complementary routes for electrophile-induced ring closures. Chiral auxiliaries, exemplified by oxazolidinones, provide time-tested stereocontrol in enolate alkylations, with facile removal after key transformations. Tandem or domino processes, such as Prins cyclisations combined with cycloetherifications, further accelerate the assembly of polycyclic frameworks in a single operation. Recently, the integration of biocatalytic halocyclisation and hydrolactonisation has opened new frontiers in mild, environmentally benign asymmetric methodologies. Collectively, these advances continue to expand the synthetic toolbox for accessing natural products with precise three-dimensional architectures, underpinning the discovery of novel pharmaceuticals and agrochemicals.

Research from Nature Portfolio

Recent studies have reported the enantioselective total synthesis of a complex meroterpenoid through a copper-catalysed intramolecular Diels–Alder cycloaddition tethered by a silicon linker, delivering a bicyclo[2.2.2]octane core with high stereocontrol. Subsequent Brønsted acid promoted tandem O-deprotection, Prins cyclisation and cycloetherification introduced multiple oxygenated rings in one sequence. Fleming–Tamao oxidation and an iron-catalysed Wacker-type oxidation were then employed to fine-tune oxidation states and install secondary hydroxyl and ketone functionalities. This convergent route exemplifies how combined organometallic and acid-catalysed processes can streamline access to architecturally elaborate natural products in enantiomerically enriched form.

Asymmetric Synthesis Techniques for Natural Products publication trend

The graph below shows the total number of articles in asymmetric synthesis techniques for natural products across all publications each year (not limited to Nature Index journals).

Technical terms

Enantioselectivity: The preferential formation of one enantiomer over its mirror image in a chiral synthesis.

Chiral auxiliary: A removable stereochemical controller attached to a substrate to induce enantioselectivity in subsequent transformations.

Organocatalyst: A small organic molecule that accelerates a chemical reaction and induces asymmetry without metal centres.

Diels–Alder cycloaddition: A [4+2] reaction between a diene and dienophile forming a six-membered ring with potential stereochemical control.

Prins cyclisation: An acid-catalysed reaction combining an alkene and an aldehyde to form tetrahydropyran or related rings.

Hydrolactonisation: Intramolecular addition of a carboxylic acid to an alkene or alkyne under catalytic conditions, yielding a lactone.

References

1. Enantioselective total synthesis of (‒)-lucidumone enabled by tandem prins cyclization/cycloetherification sequence. Nature Communications (2024).
2. A Catalytic Asymmetric Hydrolactonization. Journal of the American Chemical Society (2023).
3. Applications of oxazolidinones as chiral auxiliaries in the asymmetric alkylation reaction applied to total synthesis. RSC Advances (2016).
4. Prins cyclization-mediated stereoselective synthesis of tetrahydropyrans and dihydropyrans: an inspection of twenty years. Beilstein Journal of Organic Chemistry (2021).
5. Chemoenzymatic Halocyclization of γ,δ‐Unsaturated Carboxylic Acids and Alcohols. ChemSusChem (2019).