A concise asymmetric total synthesis of (+)-erysotramidine is described, using chiral base desymmetrisation of a meso-imide, N-acyliminium addition, retro-Diels-Alder cycloaddition and radical cyclisation as the key steps. A related route, starting from a cyclobutene-fused imide, was explored, and established a novel construction of the Erythrina alkaloid skeleton using a key ring-opening/ring-...

Artificial ribozymes catalyze a variety of chemical reactions. Their structures and reaction mechanisms are largely unknown. We have analyzed a ribozyme catalyzing Diels-Alder cycloaddition reactions by comprehensive mutation analysis and a variety of probing techniques. New tertiary interactions involving base pairs between nucleotides of the 5' terminus and a large internal loop forming a pse...

α,β-Unsaturated acylammonium salts, generated in situ from commodity acid chlorides and a chiral isothiourea organocatalyst, comprise a new and versatile family of chiral dienophiles for the venerable Diels-Alder (DA) cycloaddition. Their reactivity is unveiled through a highly diastereo- and enantioselective Diels-Alder/lactonization organocascade that generates cis- and trans-fused bicyclic γ...

2-Silicon-substituted 1,3-dienes containing non transferrable groups known to promote transmetallation were prepared by Grignard chemistry and enyne metathesis. These dienes participated in one pot metathesis/Diels-Alder reactions in regio- and diastereoselective fashions. Electron-rich alkenes showed the fastest rates in metathesis reactions, and ethylene, a commonly used metathesis promoter s...

Bromoenynamides represent precursors to a diversity of azacycles by a cascade sequence of carbopalladation followed by cross-coupling/electrocyclization, or reduction processes. Full details of our investigations into intramolecular ynamide carbopalladation are disclosed, which include the first examples of carbopalladation/cross-coupling reactions using potassium organotrifluoroborate salts; a...

A series of 1,3-dipolar cycloaddition reactions are carried out using cyclodimers of simple nitrones and various dipolarophiles; substituted isoxazolidines are isolated and identified. It is proved that such cyclodimers, in solution, are in equilibrium with their corresponding nitrones and enamines. It is also concluded that aldocyclodimers are more potent than keto-cyclodimers in establish...

Diels-Alder reactions of nickel(II) N-confused tetraarylporphyrins as dienophiles with o-benzoquinodimethane yield nickel(II) N-confused isoquinoporphyrins.

Arynes continue to stimulate new reactions and theoretical insight in aromatic chemistry. This has been driven in recent years by the exceptional versatility of 2-(trimethylsilyl)phenyl triflate (1) as a precursor to ortho-benzyne. Such compounds react under mild conditions and have enabled a substantial development of aryne chemistry both in terms of classical transformations (nucleophilic add...

The enantioselective total syntheses of 11-acetoxy-4-deoxyasbestinin D and asbestinin-12 have been completed. A glycolate aldol reaction provided a diene useful for ring-closing metathesis to form an oxonene, which was ultimately employed as a template to execute a highly stereoselective intramolecular Diels-Alder cycloaddition, forming the hydroisobenzofuran moiety. The absolute configuration ...

An eight-step linear sequence for the preparation of two diastereomers an 8-fluoro-ABC-steroid building block was developed. Key step intramolecular Diels–Alder reaction intermediate o-quinodimethane formed from a benzocyclobutene substituted with 5-fluorohex-5-en-4-one chain. This side chain prepared 6-chlorohex-1-ene by bromofluorination, elimination HBr, Finkelstein and alkylation literature...