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ChemInform Abstract A properly positioned alkoxide-metal complex, possessing a transferable ligand, can exert a high degree of regio-and stereocontrol on the delivery of that ligand to a second reactive site. Thus, the complex (IV) generated from the quinone (I) undergoes Michael addition at the β-position of the unsaturated carbonyl functionality to give the product (V). Similarly, the use of such tandem 1,2/1,4-additions permits the preparation of products with defined stereochemistry such as (VIII) or (XII); the X-ray structure of (VIII) is determined. These conjugate addition processes are not restricted to the delivery of carbon nucleophiles; the alkoxyaluminum hydride complex derived from (XIV) and LiAlH4 delivers a hydride ion at the cis-position with regard to the OH moiety to give the product (XV).

Lithium dimethylcuprate (II) reacts with the benzylselenenylcyclopentenone (I) to give an enolate which undergoes direct C-alkylation with the halides (III), producing a mixture of the isomeric cyclopentanones (IV) and (V). In contrast, alkylation of the α-allylselenenyl ketones (IX) and (XII) with benzyl bromide (X) results in the formation of the benzyl homoallyl selenides (XI) or (XIII). Treatment of the selenide (XIII) with lithium phenyl selenide yields the deselenated product (XIV).