Natural and synthetic 2H-pyran-2-ones and their versatility in organic synthesis☆

A Formal [3 + 3] Cycloaddition Approach to Natural-Product Synthesis

Syntheses of chromenes and chromanes via o-quinone methide intermediates

Evidence is described here to support that a highly stereoselective 6π-electron electrocyclic ring closure of 1-azatrienes is a key step in formal [3 + 3] cycloaddition or annulation reactions of chiral vinylogous amides with α,β-unsaturated iminium salts. This would represent the first highly stereoselective 6π-electron electrocyclic ring closure of 1-azatrienes. We have also unambiguously demonstrated that these specific ring closures are reversible, leading to the major diastereomer that is also thermodynamically more stable, and that a rotation preference likely also plays a role. A synthetic application is illustrated here to stereoselectively transform the resulting dihydropyridines to cis-1-azadecalins with unique anti relative stereochemistry at C2 and C2a, leading to synthesis of epi isomers of (−)-pumiliotoxin C.

Stereoselective Formal [3 + 3] Cycloaddition Approach to cis-1-Azadecalins and Synthesis of (−)-4a,8a-diepi-Pumiliotoxin C. Evidence for the First Highly Stereoselective 6π-Electron Electrocyclic Ring Closures of 1-Azatrienes

Sequential 1,2-Addition−Electrocyclic Ring Closures Involving Acyclic α,β-Unsaturated Iminiums: A Formal [3 + 3] Cycloaddition Strategy to Unique Pyranyl Spirocycles

The reactivity of 4-hydroxy-6-methyl-2-pyrone towards aliphatic saturated and α,β-unsaturated aldehydes

Lithiation of 1‐benzylimidazole. A hypothesis on the regioselectivity of the electrophilic attacks on the lithiated species

The reactivity of 4‐hydroxy‐6‐methyl‐2‐pyrone towards different types of ketones

Functionalization at C‐5 and at the C‐6 methyl group of 4‐methoxy‐6‐methyl‐2‐pyrone

4‐Hydroxy‐6‐methyl‐2‐pyrone (triacetic acid lactone) and its 3‐phenylthiomethyl derivative towards aldehydes in the presence of piperidine

R. Pleixats

Papers

The reactivity of 4-hydroxy-6-methyl-2-pyrone towards aliphatic saturated and α,β-unsaturated aldehydes

Lithiation of 1‐benzylimidazole. A hypothesis on the regioselectivity of the electrophilic attacks on the lithiated species

The reactivity of 4‐hydroxy‐6‐methyl‐2‐pyrone towards different types of ketones

Functionalization at C‐5 and at the C‐6 methyl group of 4‐methoxy‐6‐methyl‐2‐pyrone

4‐Hydroxy‐6‐methyl‐2‐pyrone (triacetic acid lactone) and its 3‐phenylthiomethyl derivative towards aldehydes in the presence of piperidine