Abstract
A TiCl4 /n -Bu4 NI combination induces ring opening coupling of vinylcyclopropanes with aldehydes and acetals. The coupling products obtained with this protocol can be converted into dienes in good yields.
Key words
vinylcyclopropane - titanium tetrachloride - aldehydes - quaternary ammonium halide - diene
References and Notes
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6 The use of Et2 AlI in place of TiCl4 -n -Bu4 NI provided homoallyl alcohol 2 in moderate yields. The reaction of vinylcyclopropane 1a with benzaldehyde in the presence of Et2 AlI (2.0 equiv) at 0 °C yielded homoallyl alcohol 2a in 68% yield.
7 The apparent reversed E /Z ratio results from change in the priority of R1 and the 2-hydroxyalkyl group. The sense of the stereoselectivity is the same.
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9 Vinylcyclopropanes react with acyl chlorides in the presence of SnCl4 as a Lewis acid. The use of SnCl4 in place of TiCl4 -n -Bu4 NI provided β,γ-unsaturated carbonyl compounds in good yield.
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