Bifunctionalized allenes. Part XXI. Electrophilic cyclization and addition reactions of 3-(α- or β-hydroxyalkyl)-allenylphosphonates and allenyl phosphine oxides

Abstract

The present paper discusses the electrophilic cyclization and addition reactions of 3-(α- or β-hydroxyalkyl)-allenylphosphonates and phosphine oxides. Treatment of 3-(α- or β-hydroxy-alkyl)-allenylphosphonates with electrophiles takes place with 5-endo-trig cyclization and gives 2-methoxy-2,5-dihydro-1,2-oxaphosphole 2-oxides as a result of the neighboring phosphonate group participation in the electrophilic cyclization. On the other hand, 3-(α- or β-hydroxyalkyl)-alk-(1E)-en-1-yl phosphine oxides were prepared by chemo-, regio-, and stereoselective electrophilic addition to the C²-C³-double bond in the 3-(α- or β-hydroxyalkyl)-alka-1,2-dienyl phosphine oxides and subsequent attack of the external nucleophile (halide anion). The paper proposes a possible mechanism that involves electrophilic cyclization and addition reactions of the phosphorylated (α- or β-hydroxyalkyl)allenes.

Graphical Abstract

Keywords:

• 3-(α- or β-Hydroxyalkyl)allenylphosphonates
• 3-(α- or β-hydroxyalkyl)allenyl phosphine oxides
• electrophilic cyclization
• 2,5-dihydro-1,2-oxaphospholes
• addition
• 3-(α- or β-hydroxyalkyl)-alk-(1E)-en-1-yl phosphine oxides

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the the Research Fund of the Konstantin Preslavsky University of Shumen under Grants RD-08-109/2016 and RD-08-98/2017.