Imides, alkylation conjugate addition

A thermal rearrangement of 7-oxabenzonorbornadienes mounted on a [3]polynorbornane bis-imide molecular rack has been shown to yield an oxepine using flash vacuum pyrolysis (13TL5335). Substituted oxepin-3(2Ji)-ones 67 have been shown to result from a tandem conjugate addition-alkylation-isomerization process between 1,2-allenic ketones 65 and ethyl 4-chloroacetoacetate 66 (13RA4156). 

In 1999, Jacobsen reported on a catalytic asymmetric conjugated addition of hydrazoic acid to unsaturated imide derivatives (Equation 4.1). This breakthrough was possible through the use of aluminium salen azide complex 1 as catalyst. The reaction proceeded in excellent yields and enantioselectivities for alkyl substituted acceptors. Two mechanisms were proposed for this reaction activation of the azide as an aluminium azide as shown by Chung and co-workers or Lewis acid activation of the imide. The first-order dependence of the rate law on catalyst 1 indicated that dual activation was improbable. In 2005, Jacobsen reported on the extension of this methodology to ,j8-unsaturated ketones. 

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