Stereoselective Annulation Research Articles

One‐Step Synthesis of α‐Pyrones from Acyl Chlorides by the Stille Reaction.

AbstractFor Abstract see ChemInform Abstract in Full Text.

One-step synthesis of alpha-pyrones from acyl chlorides by the Stille reaction.

Palladium-catalyzed stereoselective annulation of a functional vinylstannane by acyl chlorides gives the corresponding alpha-pyran-2-ones in good yields. This annulation most probably proceeds through a Stille reaction/cyclization sequence.

Palladium-catalysed annulation reaction of allenyltins with β-iodo vinylic acids: selective synthesis of α-pyrones

Palladium-catalysed regio- and stereoselective annulation of allenyl stannanes by β-iodo vinylic acids gives the corresponding α-pyrones in high yields. This annulation most probably proceeds through a Stille reaction/cyclisation sequence.

Palladium-Catalyzed Annulation of Allenes Using Functionally Substituted Vinylic Halides

Palladium catalyzes the regio- and stereoselective annulation of allenes by vinylic halides bearing alcohol-, amine-, sulfonamide-, carboxylic acid-, carboxamide- and carbanion-stabilizing groups to produce a variety of five- and six-membered-ring unsaturated heterocycles and carbocycles. The reaction appears to proceed by vinylic palladium formation and addition to the allene, followed by intramolecular nucleophilic displacement of the palladium. Six-membered rings are formed more readily than five-membered rings. The regioselectivity is generally high, with vinylic halides bearing alcohol, carboxylic acid, or carboxamide groups affording predominantly the product of intramolecular attack on the more substituted end of the π-allylpalladium intermediate, while amines and carbanions attack quite selectively at the less substituted end of the π-allylpalladium intermediate. Vinylic halides bearing tosylamides afford mixtures of regioisomers, where the predominant six-membered ring product arises by attack on...

Remote stereocontrol as a synthetic strategy: diastereoselective annulations on an arene tricarbonylchromium template †

Stereoselective annulations on Cr(CO)3 complexed tetralone and benzosuberone§ derivatives have been achieved. Diastereomeric products are shown to be related by an epimerisable chiral centre. An unusually facile de-ethoxycarbonylation has been observed.

ChemInform Abstract: Synthesis and Lewis Acid Assisted Rearrangement of Novel Donor‐ Acceptor Substituted Cyclopropanes: Highly Stereoselective (4 + 1) Annulation Approach to Substituted and Spiro Cyclopentene Derivatives.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A synthetic approach to the pseudopterosins

Three Lewis acid catalysed reactions used in a synthesis of the tricyclic core of the marine anti-inflammatory pseudopterosins are reported; the reductive cleavage of an oxirane with inversion, the cyclisation of an α-hydroxy ketenedithioacetal to an arene, and a stereoselective annulation using an allylic sulfone as the electrophile.

Highly regio- and stereo-selective annulation–elimination reactions of 1-cycloalkenyl 3-hydroxypropyl ethers

Highly regio- and stereo-selective annulation–elimination reactions of 1-cycloalkenyl 3-hydroxypropyl ethers in the presence of triflic anhydride and tertiary amines are described; the bicyclic vinyl ethers produced are converted to 2-substituted δ-lactones, macrocyclic oxolactones and bicyclic hydroxy ethers by ozonolysis and stereoselective hydroboration.

ChemInform Abstract: Acid‐Promoted Reaction of Cyclic Allylic Diols with Carbonyl Compounds. Stereoselective Ring‐Enlarging Tetrahydrofuran Annulations.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.