Uncatalysed reactions of zinc organometallics

PAUL KNOCHEL, PHILIP JONES, and FALK LANGER 

By using chiral diorganozincs, it is possible to obtain chiral phosphines or diphosphines of interest as ligand for metal catalysed asymmetric synthesis. 

The selective preparation of various chlorophosphines used as building blocks for the preparation of polyfunctional phosphines is achieved using dichloro (diethylamino)phosphine (Et2NPCl2). Alkylation of this phosphine with organozinc halides furnishes, after borane treatment, protected aminodi-organophosphines. These in turn can be converted to the corresponding 

The Michael-addition of zinc organometallics to enones can be catalysed by transition metals like copper16 21 or nickel.22-25 However, by using a polar cosolvent like N-methylpyrrolidinone (NMP) in the presence of TMSC1 or  

The same experimental procedure can be used with alkylidenemalonate and other related Michael-acceptors, as well as nitroolefins.26 However, under these reaction conditions only one of the two R groups of R2Zn is transferred to the enone. This problem can be solved by using mixed diorganozincs of the 

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The Reformatsky reaction,uncatalysed reactions of zinc organometallics, asymmetric additions using diorganozincs have been reviewed. 

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