This Personal Account summarizes our recent efforts in searching for novel synthetic strategies for a number of organic molecules by using allene derivatives as valuable substrates. It starts with a concise description of the background of allene-related synthetic chemistry. The second part deals with the reactions of 1,2-allenic ketones, including the reactions of 1,2-allenic ketones with various nucleophiles to afford functionalized benzenes, heterocycles, and fluoroenones, and those of allenic ketones as nucleophiles under the promotion of bases to provide 1,3,4′-triones or functionalized furans. The third part of this account focuses on the reactions of α-allenic alcohols. In this section, multicomponent reactions involving α-allenic alcohols, and cascade reactions of α-allenic alcohols promoted by Brønsted acid or iodine, are presented.

Pyrimido[4,5-b]quinolinones have attracted considerable interest from both chemical and medicinal scientists as these compounds display remarkable antimicrobial, anti-inflammatory, antitumor, antiallergy, analgesic, and antioxidant activities. The importance of pyrimido[4,5-b]quinolinones has stimulated enormous efforts to develop efficient methodologies for their synthesis. Herein, we disclose a novel synthetic protocol toward pyrimido[4,5-b]quinolin-4-ones through Cu(OAc)₂-catalyzed one-pot four-component reactions of 2-bromobenzaldehydes, aqueous ammonia, cyanoacetamides and aldehydes. The synthetic procedure combines amination/condensation/cyclization/dehydrogenation reactions in one pot, allowing synthesis of complex compounds in a simple and practical manner. Compared with literature procedures, the synthetic strategies developed herein showed advantages such as readily available and economically sustainable starting materials, structural diversity of products, good functional group tolerance, and a remarkably simple operation process.

An efficient synthesis of substituted indolizine and its benzo derivatives, pyrrolo[1,2-a]quinolines and pyrrolo[2,1-a]isoquinolines, by the reaction of allenyl ketones with α-bromo carbonyl compounds and pyridines (quinoline or isoquinoline) under mild conditions without an added oxidant other than molecular oxygen from air was developed. Notably, allenyl ketones with or without a substituent attached to the internal position of the allene moiety afforded indolizine derivatives with different substitution patterns.

The efficient syntheses of 3-cyanoquinolin-2-ones, 3-(2-bromobenzyl)-3-cyano-3,4-dihydroquinolin-2-ones, 3-(2-bromobenzyl)quinolin-2-ones, and 12H-chromeno[2,3-b]quinolin-12-ones through copper-catalyzed N- and O-arylation of amides by using readily available 2-bromobenzyl bromides and cyanoacetamides as starting materials were developed.