[3+2] Cycloaddition of Alkynyl Boronates and in situ Generated Azomethine Ylide

• Published in: Chemistry : a European journal 2024-02, Vol.30 (11), p.e202303504-n/a
• Main Authors: Liashuk, Oleksandr S., Ryzhov, Ihor A., Hryshchuk, Oleksandr V., Volovenko, Yulian M., Grygorenko, Oleksandr O.
• Format: Article
• Language: English
• Subjects: Aldehydes; bicyclic compounds; boronate; building blocks; Catalysts; Cycloaddition; Functional groups; pyrroline; Stoichiometry
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.202303504

Scalable [3+2] cycloaddition of alkynyl boronates and in situ generated unstabilized azomethine ylide is reported for the first time. The selective formation of either 1 : 1 or 1 : 2 cycloaddition products was achieved by carefully optimizing the reaction conditions, mainly by controlling the reactant stoichiometry, catalyst loading, and internal temperature. The developed protocol tolerated many valuable functional groups, including TMS, protected alcohol (as ether or THP derivatives), or aldehyde (as acetal). Further common C−C and C−heteroatom bond‐forming reactions, as well as scaled‐up procedures demonstrate the utility of the prepared compounds as building blocks for organic synthesis and drug discovery. [3+2] cycloaddition of alkynyl boronates and in situ generated azomethine ylide is used for the selective scalable synthesis of pyrroline‐ and diazabicyclo[3.3.0]octane‐derived boronates (i. e., 1 : 1 and 1 : 2 cycloadducts). The C−C and C−heteroatom bond‐forming reactions of the obtained building blocks illustrate their utility for organic synthesis and drug discovery.