Abstract
We report a study on the relationship between the polarization of C≡C bond in a series of 2‐alkynylbenzaldehydes and the regioselectivity of their Pd‐catalyzed annulation reactions. The electrophilic and nucleophilic character of the triple bond carbon atoms was examined using 13C and HMBC NMR experiments. The direction of polarization is determined only by the formyl group and its position on an aromatic ring. On the other hand, the strength of the polarization expressed through chemical shift difference Δδ of acetylenic carbon atoms is a result of electron‐withdrawing or electron‐donating ability of the other substituent. Out of two possible regioisomers, the Pd‐catalyzed cyclization reactions of 2‐alkynylbenzaldehydes that were studied predominantly afforded 1H‐isochromenes suggesting that the polarization of a triple bond is one of the contributing factors in the regioselectivity of this process.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
