Synthesis of tetrahydropyrans and related heterocycles via prins cyclization; extension to aza-prins cyclization

Metal-catalyzed amidation

Nature employs dihydroxyacetone phosphate (DHAP) as the donor component in various enzyme-catalyzed aldol reactions. Probably the most significant example in this regard is photosynthesis, in which D-glucose, the most widespread natural product, is formed in just a few steps from DHAP. In recent years a number of synthetic equivalents of DHAP have been reported that deserve particular attention, as their applicability in organic synthesis is not limited to (stereoselective) aldol reactions. The power of these reagents has also been demonstrated convincingly in numerous other asymmetric electrophilic alpha-substitution reactions in target-oriented syntheses. Furthermore, the related 1,3-dioxins are useful equivalents of 2-substituted acrolein derivatives.

The Dihydroxyacetone Unit—A Versatile C3 Building Block in Organic Synthesis

The applications of nitroalkenes in the synthesis of three- to five-membered O, N and S-heterocycles, including natural products are investigated in this review. These heterocyclic compounds were synthesized from nitroalkenes with a variety of substituents at the α and β-positions and those that were part of common and medium rings via a wide variety of reactions such as Michael addition reactions, epoxidation, [3 + 2] cycloaddition and many cascade/domino/tandem reactions. In addition, the potential of nitroalkenes to take part in multi-component and cascade reactions, particularly, in diastereo- and enantioselective versions is reviewed. The high reactivity of nitroalkenes and their potential to coordinate with the metal catalysts as well as organocatalysts signify them as efficient precursors in synthetic organic chemistry. Also, the flexibility of the nitro group in functional group manipulations has expanded the scope of the nitro group, in general, and nitroalkenes, in particular, in organic synthesis.

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Part I: Nitroalkenes in the synthesis of heterocyclic compounds

Lactic acid as an invaluable bio-based solvent for organic reactions

Intramolecular Diels-Alder cycloaddition of N-substituted oxazolone triene I allows direct entry to the functionalized octahydroquinoline II. Further manipulation of this framework by stereo- and regioselective introduction of the 5-methyl substituent, followed by excision of the carbamate, yields (+/-)-2-epi-pumiliotoxin C.

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Stephen Philip Fearnley

Papers

Oxazolone Cycloadducts as Heterocyclic Scaffolds for Alkaloid Construction – Synthesis of (±)-2-epi-Pumiliotoxin C

Preparation of 2-Alkyl- and 2-Acylpropenals from 5-(Trifluoromethanesulfonyloxy)-4H-1,3-dioxin: A Versatile Acrolein α-Cation Synthon

Intramolecular Diels–Alder reactions of N-substituted oxazolones

Intramolecular Vinylsilane−Oxocarbenium Condensations: Concise Assembly of Cis-Bicyclic Ether Arrays†

2-(3H)-Oxazolone - A Simple Heterocycle with Manifold Potential