Allylation Mediated by Zinc

Alternatively, 2-(chloromethyl)-3-iodo-l-propene reacted with aldehydes or ketones to give after basic treatment methylenetetrahydrofuran in excellent yields. The reaction is as expected chemo- and regioselective conjugated carbonyl compounds gave 1,2-addition, and aldehydes react more preferably than ketones [106]. Simharly, 3-chloro-homoallylic alcohols were prepared in high yields from the reaction of 2,3-dichloropropene with carbonyl compounds in a two-phase system containing a small amount of acetic acid. In this reaction, the presence of water in the reaction medium was shown to be essential as the reaction did not occur under non-aqueous conditions [107]. 

Propargyl halides also react with carbonyl compounds in the presence of zinc powder in concentrated aqueous salt solutions to give homopropargylic alcohols with high selectivity. High yields are obtained with aromatic and aliphatic aldehydes whereas ketones react only partially [1081. 

Hannessian and co-workers recently reported the allylation of AT-protected a-amino aldehydes as an efficient route to Phe-Phe hydroxyethylene dipeptide iso-stere utilized for the design of potential inhibitors of renin and HIV-protease 

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