[85028-55-3] · C14H23AlSe · Diisobutylaluminum Phenyl Selenide · (MW 297.28)
Solubility: sol toluene, CH2Cl2, hexane.
Form Supplied in: prepared in situ from commercially available reagents.
Preparative Methods: by addition of Diphenyl Diselenide (1 equiv) to a 1 M hexane solution of Diisobutylaluminum Hydride (2 equiv) in CH2Cl2 at 0 °C for 30 min.1
Handling, Storage, and Precautions: use in a fume hood; the dry solid and solutions are highly flammable and must be handled in the absence of oxygen and moisture; the solution should be used as prepared for best results.
Treatment of cyclododecanone and acetophenone oxime methanesulfonates with diisobutylaluminum phenyl selenide (1.1 equiv) in hexane/CH2Cl2 at 0 °C for 30 min provides the corresponding imino selenoethers in good yields via organoaluminum-promoted Beckmann rearrangement of oxime sulfonates and subsequent trapping of the intermediary iminocarbocation by phenyl selenide (eqs 1 and 2).1,2 Dimethylaluminum methyl selenide is also employable for this transformation.3
A new method for preparation of monoselenoacetals has been developed which involves the reaction of acetals with diisobutylaluminum phenyl selenide.4 When Dimethoxymethane was treated with diisobutylaluminum phenyl selenide (1 equiv) in hexane/toluene at 40 °C for 5 h, methoxy(phenylseleno)methane was formed in 98% yield (eq 3). Diethylaluminum ethyl selenide is also employable as a selenolate agent. Alkyl methoxymethyl ethers are transformed to the alkyl phenylselenomethyl ethers with high selectivity under similar reaction conditions (eq 4). Diselenoacetals are accessible with excess amounts of diisobutylaluminum phenyl selenide (eq 5).
1-Methoxy-1-(phenylseleno)ethane, prepared in this way, generates the 1-methoxyethyl radical upon treatment with catalytic Azobisisobutyronitrile and Tri-n-butylstannane in benzene at 80 °C for 2 h, and this radical adds to methyl acrylate to furnish a Michael adduct in good yield (eq 6).5
Treatment of an a,b-epoxy alcohol with NaSePh affords the 1,3-diol exclusively in 90% yield. However, use of diisobutylaluminum phenyl selenide in CH2Cl2 at 0 °C to rt exhibits the opposite regioselectivity, furnishing the 1,2-diol as a major product (eq 7).6 When diisobutylaluminum phenyl selenide is combined with Titanium Tetraisopropoxide as a cocatalyst, the selectivity of epoxide opening is considerably lowered. Dimethylaluminum Methylselenolate was less selective for this transformation, giving two isomeric diols in a 1:2 ratio. This tendency is also observed with the epoxy t-butyldimethylsilyl ether substrate (eq 8).
Keiji Maruoka & Hisashi Yamamoto
Nagoya University, Japan