Enantioselective total synthesis and absolute configuration of the alleged structure of crassinervic acid

Current-Regulated Selective Nickel-Catalyzed Electroreductive Cross-Electrophile Carbonylation to β/γ-Hydroxy Ketones

The nickel catalyzed multi-component cross-electrophile carbonylation which emerges as a powerful and efficient method for constructing diverse ketones has attracted increasing attention of organic chemists. However, the selectivity of this reaction poses a significant challenge. In this work, we have developed a current-regulated selective nickel-catalyzed electroreductive cross-electrophile carbonylation, which offers a direct convergent synthesis of β/γ-hydroxy ketones, which represent pivotal structural motifs found in numerous natural products, bioactive molecules, pharmaceutical compounds, and essential building blocks. A diverse range of multi-substituted β/γ-hydroxyketones can be accessed with high chemo- and regioselectivity from epoxides, aryl iodides, and a simple CO source (ClCO2Pr). This electroreductive carbonylation strategy exhibits high functional group tolerance and can be applied in late-stage derivatization of drugs and natural products. Notably, chiral epoxides can be employed as reactants with chirality retention, enabling the synthesis of asymmetric β-hydroxy ketones. Our approach demonstrates a novel electrochemical selectivity-controlled strategy in multi-component cross-electrophile coupling.

Developments in the Catalytic Asymmetric Synthesis of Agrochemicals and Their Synthetic Importance

Catalytic asymmetric synthesis has become an essential tool for the enantioselective synthesis of pharmaceuticals, natural products, and agrochemicals (mainly fungicides, herbicides, insecticides, and pheromones). With continuous growing interest in both modern agricultural chemistry and catalytic asymmetric synthesis chemistry, this review provides a comprehensive overview of some earlier reports as well as the recent successful applications of various catalytic asymmetric syntheses methodologies, such as enantioselective hydroformylation, enantioselective hydrogenation, asymmetric Sharpless epoxidation and dihydroxylation, asymmetric cyclopropanation or isomerization, organocatalyzed asymmetric synthesis, and so forth, which have been used as key steps in the preparation of chiral agrochemicals (on R&D, piloting, and commercial scales). Chiral agrochemicals can also lead the new generation of such chemicals having specific and novel modes of action for achieving sustainable crop protection and production. Some perspectives and challenges for these catalytic asymmetric methodologies in the synthesis of chiral agrochemicals are also briefly discussed in the final section of the manuscript. This review will provide the insight regarding understanding, development, and evaluation of catalytic asymmetric systems for the synthesis of chiral agrochemicals among the agrochemists.

Total Synthesis of Nominal ent-Chlorabietol B

The nominal enantiomer of chlorabietol B was regio- and stereoselectively synthesized from (-)-abietic acid in 13 steps. Key features of the synthesis involved an oxidative [3+2] cycloaddition to install the dihydrobenzofuran moiety and an Aldol reaction, followed by elimination and reduction steps to introduce the long chain with three cis double bonds. However, obvious differences in the NMR spectra of the synthetic and natural samples suggested that the proposed structure of chlorabietol B should be revised carefully.

Enantioselective synthesis of boron-substituted quaternary carbon stereogenic centers through NHC-catalyzed conjugate additions of (pinacolato)boron units to enones

The first examples of Lewis base catalyzed enantioselective boryl conjugate additions (BCAs) that generate products containing boron-substituted quaternary carbon stereogenic centers are disclosed. Reactions are performed in the presence of 1.0-5.0 mol% of a readily accessible chiral accessible N-heterocyclic carbene (NHC) and commercially available bis(pinacolato)diboron; cyclic or linear α,β-unsaturated ketones can be used and rigorous exclusion of air or moisture is not necessary. The desired products are obtained in 63-95% yield and 91:9 to >99:1 enantiomeric ratio (e.r.). The special utility of the NHC-catalyzed approach is demonstrated in the context of an enantioselective synthesis of natural product antifungal (-)-crassinervic acid.

Total synthesis of gonytolides C and G, lachnone C, and formal synthesis of blennolide C and diversonol

The total syntheses of gonytolide C and related compounds have been accomplished from the aldol reaction between acetophenone derived from orcinol and butyrolactone containing ketone, followed by the diastereoselective intramolecular cyclization.