A direct catalytic synthesis of substituted α-benzyloxyamino-γ-butyrolactones is reported, starting from simple oxime acids and alkenes. The substituted O-benzyloxime acid starting materials are cyclized with oxidizable alkenes, via Polar Radical Crossover Cycloaddition (PRCC) reactions. The catalytic reaction is carried out using the Fukuzumi acridinium photooxidant and substoichiometric amounts of a redox-active cocatalyst. The utility of this method has been demonstrated through the use of 3 oxime acids and 19 oxidizable olefins.

Halofunctionalization of alkenes is a classical method for olefin difunctionalization and give rise to adducts which are found in many natural products, biologically active molecules, and offer a synthetic handle for further manipulation. Classically, this reaction is performed with an electrophilic halogen source and gives rise to regioselective formation of the halofunctionalized adducts. In this work, we demonstrate a reversal of the native regioselectivity for alkene halofunctionalization reactions through the use of an acridinium photooxidant in conjunction with a copper cocatalyst.

Halofunctionalization of alkenes is ac lassical method for olefin difunctionalization. It gives rise to adducts which are found in many natural products and biologically active molecules,a nd offers as ynthetic handle for further manipulation. Classically,t his reaction is performed with an electrophilic halogen source and leads to regioselective formation of the halofunctionalized adducts.H erein, we demonstrate ar eversal of the native regioselectivity for alkene halofunctionalization through the use of an acridinium photooxidant in conjunction with ac opper cocatalyst. Scheme 1. Alkene halofunctionalization: Catalytic reversal of regioselectivity.LED = light-emitting diode, NBS = N-bromosuccinimide. Scheme 2. Scope of the alkene halofunctionalization reaction. Products were isolated as single regioisomers except where noted. [a] CuCl 2 /phen (10 mol %), NCP (1 equiv);[ b] CuBr 2 /bpy (10 mol %), DEBM (1 equiv);[ c] CuCl 2 /phen (10 mol %), NCS (1 equiv);[d] CuBr 2 /phen (10 mol %), NBP (1 equiv);[ e] with AcOH (5.0 equiv);[f] with 2,6-lutidine( 10 mol %). Boc = tert-butoxycarbonyl, DCE = 1,2-dichloroethane, Ms = methanesulfonyl. Scheme 3. Initial mechanistic proposal. Angewandte Chemie Communications

Title compounds are synthesized from simple oxime acids such as (II) and (VIII) and oxidizable alkenes using the Fukuzumi acridinium photooxidant and substoichiometric amounts of diphenyl disulfide as a redox‐active cocatalyst.

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