Stereoselective Synthesis of (<i>E</i>)-2-En-4-ynoic Acids with Ynolates: Catalytic Conversion to Tetronic Acids and 2-Pyrones

A highly torquoselective olefination of alkynoates to provide functionalized tetrasubstituted olefins, (E)-2-en-4-ynoic acids, is described. Addition of Brønsted acids dramatically switched the mode of the Ag(I)-catalyzed cyclization of the resulting enyne carboxylic acids to give either tetronic acids or 2-pyrones

Cu(II)-Catalyzed Acylation by Thiol Esters Under Neutral Conditions: Tandem Acylation-Wittig Reaction Leading to a One-Pot Synthesis of Butenolides

The first catalytic acylation of alcohols with a thiol ester present in Wittig reagents under neutral conditions catalyzed by the Cu(II) salt through a push−pull mechanism is reported. Furthermore, a new methodology for the one-pot lactonization of acyloins by a copper catalyst is developed. The synthetic utility of this method for the synthesis of natural products is shown

Cu(II)-Catalyzed Acylation by Thiol Esters Under Neutral Conditions: Tandem Acylation-Wittig Reaction Leading to a One-Pot Synthesis of Butenolides

The first catalytic acylation of alcohols with a thiol ester present in Wittig reagents under neutral conditions catalyzed by the Cu(II) salt through a push−pull mechanism is reported. Furthermore, a new methodology for the one-pot lactonization of acyloins by a copper catalyst is developed. The synthetic utility of this method for the synthesis of natural products is shown

Hyperconjugative Effects in the Stereoselective Ring-Opening Reactions of Oxetenoxides

Unexpectedly, the pattern of the stereoselectivity in the ring-opening reactions of lithium oxetenoxides is not consistent with the bulkiness of substituents, and both the bulkier tert-butyl and silyl substituents favor inward rotation. With the aid of B3LYP calculations, the hyperconjugative interaction between the breaking C1−O σ and its anti-periplanar Z-Me (Z = Si or C) σ* orbital is found to be responsible among the secondary orbital interactions of the substituents and the oxetene moiety

Efficient Synthesis of Dissymmetric Malonic Acid <i>S</i>,<i>O</i>-Esters via Monoalcoholysis of Symmetric Dithiomalonates under Neutral Conditions

A novel method for the highly selective synthesis of dissymmetric S,O-malonates starting from symmetric diphenyl dithiomalonates under neutral conditions is described. The key step is the thermal formation of an acylketene, the stability of which would contribute to the selectivity. The synthetic utility of the dissymmetric S,O-malonates is also shown

Stereoelectronic Effect on Stereoselective Olefination of Ketones Providing Tetrasubstituted Olefins via Ynolates

Stereoelectronic Effect on Stereoselective Olefination of Ketones Providing Tetrasubstituted Olefins via Ynolate

A Novel Tandem [2 + 2] Cycloaddition−Dieckmann Condensation with Ynolate Anions. Efficient Synthesis of Substituted Cycloalkenones and Naphthalenes via Formal [<i>n</i> + 1] Cycloaddition

A novel tandem [2 + 2] cycloaddition−Dieckmann condensation via ynolate anions is described. Ynolate anions are useful for the formation of reactive β-lactone enolates via a pathway not involving the enolization of the corresponding β-lactones. The [2 + 2] cycloaddition of ynolate anions with δ- or γ-keto esters, followed by Dieckmann condensation, gives bicyclic β-lactones, which are easily decarboxylated to produce synthetically useful 2,3-disubstituted cyclopentenones and cyclohexenones in one pot. This tandem reaction was applied to a novel, one-pot synthesis of highly substituted naphthalenes

The Effect of Alkynyl Groups on Torquoselectivity. Highly Stereoselective Olefination of Alkynyl Ketones with Ynolates

The Effect of Alkynyl Groups on Torquoselectivity. Highly Stereoselective Olefination of Alkynyl Ketones with Ynolate

A Novel Tandem [2 + 2] Cycloaddition−Dieckmann Condensation: Facile One-Pot Process To Obtain 2,3-Disubstituted-2-cycloalkenones from Ynolates

A Novel Tandem [2 + 2] Cycloaddition−Dieckmann Condensation:  Facile One-Pot Process To Obtain 2,3-Disubstituted-2-cycloalkenones from Ynolate

The Effect of Alkynyl Groups on Torquoselectivity. Highly Stereoselective Olefination of Alkynyl Ketones with Ynolates

The Effect of Alkynyl Groups on Torquoselectivity. Highly Stereoselective Olefination of Alkynyl Ketones with Ynolate