((E)-3-Iodo-1-methylpropenyl)-trimethylsilane

Physical properties

bp 60 °C/20 mmHg.

Uses

(E)-1-Iodo-3-trimethylsilyl-2-butene can be used as annulation reagent; alkylative equivalent of 3-buten-2-one; 3-ketobutyl synthon.

Preparation

the first reported preparation of this reagent lacked full experimental details. The preparation given is a compilation of thework of several groups; the various steps have been selected to give optimum yields. 2-Propyn-1-ol is converted3 into its 3-(trimethylsilyl) derivative (1), which is then reduced4 using sodium bis(2-methoxyethoxy)aluminum hydride (Red-Al). The intermediate vinylaluminum is reacted with iodine to produce the (Z)-iodoalkene (2). Treatment of this with lithium dimethylcuprate gives the allylic alcohol (3);. transformation into (E)-(3-chloro-1-methyl-1-propenyl)trimethylsilane (4) followed by halogen exchange with sodium iodide then gives reagent (5).