Etherification reactions of propargylic alcohols catalyzed by a cationic ruthenium allenylidene complex

• A ruthenium catalyzed etherification of propargylic alcohols is reported.
• The catalyst load is only 1.1 mol% and no further additives are required.
• After heating at 100 °C for 18 h, the catalyst was not deactivated.

The cationic ruthenium allenylidene complex RRuRax −[Ru(indenyl)L(PPh3)CCCPh2]+PF6 catalyzes the etherification of secondary and tertiary propargylic alcohols in a formal nucleophilic substitution reaction utilizing primary and secondary alcohols as the nucleophiles. At a catalyst loading of only 1.1 mol%, the corresponding propargylic ether products were obtained in 9 to 73% isolated yields (18 h reaction time at 100 °C); no further additives are required. The reaction exhibits an induction period; as shown by a control reaction, the high reaction temperature may chemically change the allenylidene complex to be employed as the catalyst but does not lead to catalyst deactivation.

Figure optionsDownload as PowerPoint slide