Steric strain in syn[2.2]Metacylophane.

✍ Scribed by Shô Itô; Yoshisuke Nakasato; Yutaka Fujise; Hideaki Hioki; Miwa Nagaku; Yoshimasa Fukazawa

• Book ID: 104215861
• Publisher: Elsevier Science
• Year: 1993
• Tongue: French
• Weight: 129 KB
• Volume: 34
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)79229-x

✦ Synopsis

Absbu& The conformation of syn-5,13dimethyl[2.2]metac crystallographic analysis, and its steric energy evaluated by lJ clophane was established by X-ray M2 calculations. Based on these data the steric ?rain inherited in the compound was concluded to originate mainly from the nearly eclipsed conformamm of two ethano bridges. In 1986 we achieved the synthesis of syn-5.l3-dimethyl[2.2]metacyclophane (Is)? the 2nd member of ryn[2.2]metacyclophanes with no substituent at inner positions: It is surprisingly stable; no decomposition at room temperature in the solid state, sublimes at -75°C to the sari isomer la, and isomerizes to la at temperatures above O'C in solution? Interested in the origin of the unexpected stability, we have evaluated its inherent strain utilizing molecular mechanics calculations.