Addition of a 3-alkoxy allenylzinc to N-acyliminium ions: new entry to propargyl syn-1,2-aminoalcohol units

A new addition reaction of a 3-alkoxy allenylzinc reagent to N-acyliminiums prepared in situ from imines and acid halides is reported. Unlike addition onto imines or nitrones that affords the trans adducts, acetylenic syn-1,2 amino ethers are yielded with good selectivities, thus providing a new entry to propargyl syn-1,2-aminoalcohol units.