Total Synthesis and Assignment of the Absolute Configuration of (+)-Omphalic Acid

Mukaiyama aldol reaction: an effective asymmetric approach to access chiral natural products and their derivatives/analogues

The Mukaiyama aldol reaction is generally a Lewis-acid catalyzed cross-aldol reaction between an aldehyde or ketone and silyl enol ether. It was first described by Mukaiyama in 1973, almost 5 decades ago, to achieve the enantioselective synthesis of β-hydroxy carbonyl compounds in high percentage yields. Mukaiyama aldol adducts play a pivotal role in the synthesis of various naturally occurring and medicinally important organic compounds such as polyketides, alkaloids, macrolides, etc. This review highlights the significance of the Mukaiyama aldol reaction towards the asymmetric synthesis of a wide range of biologically active natural products reported recently (since 2020).

Recent Progress in the Synthesis of Sesquiterpenoid Involving Spirocyclic Carbon Framework

Spirocarbocyclic natural products have been attracting considerable attention from synthetic organic chemists. This review focused on total syntheses of sesquiterpenoids involving spiro[4.5]decane and spiro[5.5]undecane scaffolds, compiling syntheses of colletoic acid, cubebol, axenol, vetispirene, hinesol, agarospirol, axenol, gleenol, exiguamide, exigurin, erythrodiene, spirojatamol, antroalbocin A, omphalic acid, dactylone, and aplydactonee since 2015.

Catalytic Asymmetric Spirocyclizing Diels-Alder Reactions of Enones: Stereoselective Total and Formal Syntheses of α-Chamigrene, β-Chamigrene, Laurencenone C, Colletoic Acid, and Omphalic Acid

We disclose a general catalytic enantioselective Diels–Alder reaction of exo-enones with dienes to give spirocyclanes. The obtained products feature highly congested quaternary stereogenic spirocenters and are used in concise total and formal syntheses of several sesquiterpenes, including of α-chamigrene, β-chamigrene, laurencenone C, colletoic acid, and omphalic acid. The stereo- and regioselectivities of our spirocyclizing cycloaddition are effectively controlled by strongly acidic and confined imidodiphosphorimidate catalysts. Computational studies shed light on the origin of reactivity and selectivity.