Stereoselective inverse conjugate addition of nitrogen and carbon nucleophiles to allenyl phosphine oxide. Synthesis of α,β-unsaturated phosphine oxides

Jesús M De Los Santos,Zelai Ochoa,Francisco Palacios,Gyorgy Hajos

doi:10.3998/ark.5550190.0013.406

Abstract

The reactivity of new three carbon synthon, generated in situ from the reaction of electron- deficient allenes with an appropriate phosphine as the catalyst, toward pronucleophilic reagents is described. Triphenylphosphine-catalyzed reaction of allenes derived from phosphine oxides with nitrogen- or carbonucleophiles gave the γ-addition product as a mixture of cis and trans isomers.

Highlights

In recent years, electron-deficient allenes have emerged as attractive electrophiles for various synthetic purposes.[1]
Taking into account our interest in the synthesis of allenes and their use as building blocks in organic synthesis,[8] we have recently describe the first approach for the construction of tertiary and quaternary stereocenters via stereoselective γ-addition of carbonucleophiles to allenes bearing a chiral auxiliary.[9]
It has been previously observed that the selection of the appropriated temperature, solvent and phosphine stoichiometry is important to optimize this umpolung reaction.6b the γ-addition of phthalimide 2a to allene 1 leading to compound 3 was carried out under different reaction conditions (Scheme 2, Table 1, entries 1–5)

Summary

Introduction

Electron-deficient allenes have emerged as attractive electrophiles for various synthetic purposes.[1]. Triphenylphosphine-catalyzed reaction of allenes derived from phosphine oxides with nitrogen- or carbonucleophiles gave the γ-addition product as a mixture of cis and trans isomers.

Results

Conclusion