Alkynyl propargylic carboxylates

In general, allylic and propargyllic electrophiles are much more reactive than alkenyl and alkynyl electrophiles. Thus, a wide variety of electrophiles containing halogens, e.g. I, Br, and Cl, and oxygen groups, e.g. sulfonates, phosphates, carboxylates, carbonates, alkyl and aryl ethers, and even silyl... 

Alkynylepoxides [123,142,143 Eq. (68) 142] and alkynyl propiolactones [Eq. (69) 144] afforded allenyl-alcohols or allenyl-carboxylic acids. Diastereoselective ring opening of alkynylepoxides has been studied [143,145]. The use of optically active propargyl substrates enables the synthesis of optically active allenes [Eq. (70) 146] [10,140,145-147]. A subtle change of the reaction medium may drastically change the degree of chirality transfer, which has been systematically examined [145]. 

Cross coupling of EtsAl with aryl phosphates or alkynyl bromides proceeds with a Ni catalyst to provide alkylated arenes or aUrynes (eqs 5 and 6). While Pd or Cu complexes are used as the catalyst for the coupling of EtsAl with carboxylic acid chlorides or thioesters (eq 7), Iron(HI) Chloride is used for reactions of propargyl acetates to give substituted allenes (eq 8)."... 

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