Science of Synthesis

Zeller, K.-P., Science of Synthesis, (2001) 9, 37.

The introduction of the oxirene double bond should be achievable by β-elimination reactions of suitable 1,2-disubstituted oxiranes. The most obvious way would be the dehydrohalogenation of halooxiranes. The exo-oxide ‌111‌ of 2-chlorobicyclo[2.2.1]heptene, when heated under reflux in a benzene/diethyl ether solution in the presence of excess lithium diethylamide as base, affords tricyclo[2.2.1.02,6]heptan-3-one (‌116‌) as the major product (84%)[‌73‌] (‌Scheme 28‌). Clearly, compound ‌116‌ arises from intramolecular carbenoid insertion; however, nothing is known about the origin of the α-oxo carbene (or carbenoid) intermediate ‌113‌. It could be formed via carbanion ‌112‌ or via the oxirene ‌115‌. The same reaction product is obtained when the exo-oxide ‌114‌ of 2,3-dichlorobicyclo[2.2.1]heptene is dehalogenated with zinc in dioxane.[‌74‌] In this case, oxirene ‌115‌ and α-oxo carbene ‌113‌ have been suggested as intermediates (‌Scheme 28‌).

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References

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• 8.Meeeee-Meee, (8888) M 88e8, 8888.