Transmission of electronic effects through 2-[donor]-1-[acceptor] cyclopropanes. Part III. Conformational studies of 2-(p-x-aryl)-1-cyclopropane aldehydes with lanthanide shift reagents.

✍ Scribed by Miguel E. Alonso; José Daniel Gómez; Sarah V. Pekerar

• Book ID: 104204412
• Publisher: Elsevier Science
• Year: 1993
• Tongue: French
• Weight: 614 KB
• Volume: 49
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(01)87219-7

✦ Synopsis

Substituent mesomeric eflects transmitted through cyclopropane have been examined by the influence that a p-x-atyI group (X= OMe, Me, H, Cr) on C2 might have on preferential conformer popukztions of an a&?&z unit on Cl in solution. The lanthanide induced sh# method, which proved to be applicable to this non rigid system by testing the structural sev consistency of the model with OhhznWs correhztim, was used to determine the prefemed C-C=O rotational angk 7 rehztive to the cyclopropane plane. This gave t around 3P-50' away from the bisected conformation in the direction of the Cl-C3 bond irrespective of the electron

withakwer or donor nature of the arene substituents. This showed that true mesomeric eflects do not occur in cyclopropane. Imte&, competitive conjugation of substituents for the electron dens@ in the ring is the dominant feature, as predicted by conventionaiM theory,