A CONVENIENT METHOD FOR THE SYNTHESIS OF δ-ALKOXY-β-KETOESTER THE TITANIUM TETRACHLORIDE-ACTIVATED REACTION OF DIKETENE WITH ACETAL
作者:Toshio Izawa、Teruaki Mukaiyama
DOI:10.1246/cl.1974.1189
日期:1974.10.5
It was established that, in the presence of TiCl4, diketene [1] reacts with acetals [2] at −78∼−20°C to afford δ-alkoxy-β-ketoesters [3] in good yields. This reaction provides a novel method for the introduction of –COCH2COCH2– unit to an electrophile as acetal activated by TiCl4.
Treatment of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with alpha -chlorocarboxylic acid chlorides resulted in chemo- and regioselective formation of 6-chloro-3,5-dioxo esters, which were regioselectively converted into functionalised 3(2 H)furanones. Chemo- and regioselective condensation of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with alpha -chloroacetic dimethyl acetal afforded 6-chloro-5-methoxy-3-oxo esters, which could be regio- and stereoselectively transformed into 2-alkylidene-4-methoxytetrahydrofurans.