The Favorsky reaction of a wide range of aldehydes and ketones with alkynes has been implemented under mild conditions (5–20 °C). Using a Bu4NOH/H2O/DMSO catalytic system, propargylic alcohols are formed cleanly in 39–93 % (mostly 72–93 %) yields and with ca. 100 % selectivity. The method is suitable for aliphatic, aromatic, and heteroaromatic aldehydes and ketones, and for aliphatic, aromatic, and functionalized acetylenes. Thus, this represents the most general and efficient protocol to achieve the Favorsky reaction.

Acetylene reacts with methylaryl(hetaryl)ketones in the presence of 6.5 mol % KOH in DMSO to give diastereoselectively in single operationally functionalized cyclopentenes. This domino cyclization involving two molecules of acetylene and two molecules of ketone proceeds with the formation of four C-C bonds. The complementary assembly of the cyclopentenes with similar functionalities from acetylenes and 1,5-diketones has been developed.

Base-Catalyzed Domino Cyclization of Acetylenes with Ketones to Functionalized Cyclopentenes. -(SCHMIDT, E. Y.; TROFIMOV*, B. A.; BIDUSENKO, I. A.; CHERIMICHKINA, N. A.; USHAKOV, I. A.; PROTZUK, N. I.; GATILOV, Y. V.; Org. Lett. 16 (2014) 15, 4040-4043, http://dx.

Ketones with bulky aromatic, heteroaromatic and ferrocene substituents react with acetylene in the presence of a KOH/DMSO super-base suspension (90 °C, 15 min) to give polysubstituted furans in up to 86 % isolated yields in a one-pot fashion. This assembly of the furan scaffold involves a domino sequence in which one molecule of ketone reacts with two molecules of acetylene.

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