Ethyl allenoate

Tricyclohexylphosphine can catalyze the reaction of ethyl allenoate with aldehydes to afford 6-substituted 2H-pyran-2-ones, which represents a type (iii) synthesis of 2//-pyran-2-ones (Equation 256) <2005OL2977>. 

A formal [4h-2] cycloaddition between arylidenoxin-doles and ethyl allenoate afforded dihydropyran-fused indoles, as shown by Wang and colleagues (Scheme 10, equation 1) [67]. Density functional theory (DFT) implicates a stepwise mechanism. A not-unrelated synthesis of indole-annulated dihydropyrano[3,4-c]chromenes via a hetero-Diels-Alder reaction was discovered by Jha and colleagues (equation 2) [68]. The requisite precursors 26... 

The reaction of ethyl allenoate 231 with the enone 232 in the presence of 2-phospha-[3]-ferrocenophanes affords the [3+2] annulation product 233 in 85 % yield (80 % ee). ... 

A Baylis-Hillman type product has been obtained through a ring-opening reaction of an epoxide with an allenoate <06OL2771>. The reaction of MgL, with ethyl propiolate provides the iodo allenoate 32. This nucleophile reacts with an aryl epoxide to provide the homoallylic alcohol 33. The Z iodide is the major product formed. 

To a dry flask filled with nitrogen were added the ketimine (0.2 mmol) and allenoate (0.4 mmol) in 2mL CHCI3. PPhj (0.04 mmol) was added. This solution was stirred at 60 °C until the complete consumption of the starting material as monitored by TLC. After the removal of the solvent, the residue was subjected to chromatography on a silica gel (60-120mesh) column using 20 1 petroleum ether/ethyl acetate solvent mixture as eluent to afford the aza-bicyclo[3,3,0]octane derivative. 

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