Vanadyl Bis(acetylacetonate)-Azobisisobutyronitrile


[3153-26-2]  · C10H14O5V  · Vanadyl Bis(acetylacetonate)-Azobisisobutyronitrile  · (MW 265.18) (AIBN)

[78-67-1]  · C8H12N4  · Vanadyl Bis(acetylacetonate)-Azobisisobutyronitrile  · (MW 164.24)

(catalyst for oxygen-promoted allylic oxidation coupled with hydroxyl-directed epoxidation of C=C double bonds1)

Physical Data: AIBN: solid, mp 100 °C (dec). VO(acac)2: solid, mp 250 °C (dec).

Solubility: see Azobisisobutyronitrile and Vanadyl Bis(acetylacetonate). The combination may be used in 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2-trichloroethane, acetonitrile, benzene, 1,4-dioxane, or n-hexane.

Form Supplied in: AIBN is sold as a white solid; VO(acac)2 is sold as a green powder.

Handling, Storage, and Precautions: see the individual entries for AIBN and VO(acac)2. AIBN causes convulsions.

Allylic Oxidation/Epoxidation Reactions.

The reagent combination is an effective catalyst for the oxidation of cyclic alkenes, except cyclooctene, to epoxy alcohols using molecular Oxygen as the oxidant. The conversion proceeds by way of allylic oxidation to give an allylic hydroperoxide, which is reduced by the metal to give an allylic alcohol. Hydroxyl-directed epoxidation of the latter intermediate occurs in situ to give the epoxy alcohol. Cyclohexene is converted to (1), together with (2), (3), and (4), the relative amounts of which depend on reaction conditions, primarily solvent (eq 1). Best results are obtained by using cyclohexene (20 mmol), VO(acac)2 (0.01 mmol), AIBN (0.1 mmol), O2 (1 atm), and 1,1,2-trichloroethane (2.0 mL) at 60 ± 1 °C, which gives 30% yield of a mixture of (1) (65%), (2) (17%), (3) (5%), and (4) (13%). While similar conversions can be effected by O2 in the presence of CpV(CO)4 or V2O5, and by VO(acac)2 in the absence of AIBN, the yields and product distribution differ from those obtained by using the title reagent.

1,4-Cyclooctadiene undergoes a transannular epoxidation reaction under the above reaction conditions to give a mixture of (5) (43%) and four other products (57% combined yield; the published results are not clear), from which crystalline (5) can be obtained in 18% yield by chromatography on Florisil, followed by sublimation of the residue (eq 2).

1. Kaneda, K.; Jitsukawa, K.; Itoh, T.; Teranishi, S. JOC 1980, 45, 3004.

Anthony J. Pearson

Case Western Reserve University, Cleveland, OH, USA

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