Table 1. Preparation of α-Allenols from Propargyl Substrates with Acetate and Protected Hydroxyl on Opposite Sides of the Alkynea.
Isolated yields. Conditions: 0.1 M solution of substrate 1 (1 equiv), R4 MgX (1.25 equiv), and 1 mol % of Fe(acac)3 in Et2O, addition of R4 MgX for 5 and 10 min reaction time.
R4 MgX (1.5 equiv), 5 mol % of Fe(acac)3.
R4 MgX (1.75 equiv), 7.5 mol % of Fe(acac)3.
R4 MgX (1.75 equiv), 5 mol % of Fe(acac)3.
5 mol % of Fe(acac)3.
R4 MgX (2 equiv), 7.5 mol % of Fe(acac)3.