Electrophilic addition to allenic derivatives: selectivity, regio- and stereochemistry and mechanisms

Expeditious Syntheses of Conjugated Allenyl Esters and Oxazoles through a Cascade Reaction of .ALPHA.-Alkynyl Malonates under Alkaline Conditions

“…[1][2][3][4][5][6][7][8][9] Allenylic compounds have been efficiently utilized as a key intermediate to synthesize biologically active natural products. [10][11][12] The specific reactivities of allenylic compounds have been widely applied to carbon-carbon and carbon-hetero atom cyclizations, aldol reactions, DielsAlder reactions, [2ϩ2] and [4ϩ2] cycloadditions, etc.…”

“…[13][14][15][16][17][18][19] Because of this usefulness of allenes, there have been many reports on methods for constructing the allenylic moieties. [1][2][3][4][5][6][7][8][9][20][21][22][23][24][25][26] Previously, we communicated a characteristic synthetic method for conjugated allenyl esters and trisubstituted oxazoles via alkaline hydrolysis of diethyl a-alkynyla-methoxy(or acetylamino)malonates followed by decarboxylation of the corresponding resultant monocarboxylates in a cascade reaction manner. …”

Stereochemistry of the Asymmetric Carbopalladation of Allenes Followed by Nucleophilic Substitution Reactions with Carbo- and Aminonucleophiles

“…6,7) The axial chirality has received much attention for the stereochemical characteristics, and many methodologies of the asymmetric synthesis of allenes with the axial chirality have been reported so far.8) Currently, the use of the allene functionality in transition metal-catalyzed reactions has become of great importance from the synthetic and theoretical points of view with regard to the chemical characteristics associated with the axial chirality.9-12) Therefore, an allene with the axial chirality might be a synthetically useful chiral director for the elaboration of chiral complex organic molecules in asymmetric synthesis with metal catalysts. For the approach to chiral allenes, however, few synthetically useful methodology has been devised so far by asymmetric synthesis, especially with catalytic versions, [13][14][15][16][17] despite the efforts to access chiral allenes that were made by many investigators.…”

“…6,7) The axial chirality has received much attention for the stereochemical characteristics, and many methodologies of the asymmetric synthesis of allenes with the axial chirality have been reported so far.…”

“…6,7) The axial chirality has received much attention for the stereochemical characteristics, and many methodologies of the asymmetric synthesis of allenes with the axial chirality have been reported so far. 8) Currently, the use of the allene functionality in transition metal-catalyzed reactions has become of great importance from the synthetic and theoretical points of view with regard to the chemical characteristics associated with the axial chirality.…”