The Cubane Cage – A Sensitive Probe for Assessing Substituent Effects on a Four-Membered Ring, Part II

✍ Scribed by Hermann Irngartinger; Stefan Strack; Frank Gredel; Andreas Dreuw; Ernest W. Della

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 234 KB
• Volume: 1999
• Category: Article
• ISSN: 1434-193X
• DOI: 10.1002/(sici)1099-0690(199905)1999:5<1253::aid-ejoc1253>3.0.co;2-m

✦ Synopsis

The crystal structures of methyl 4-methoxycubane-1-length with respect to the orientation of this group relative to bonds within the cubane skeleton has been investigated carboxylate (1), 1-acetamido-4-fluorocubane (2), methyl 4acetoxycubane-1-carboxylate (3), 1,4-difluorocubane (4), 1,4-experimentally. The effect of the methoxy group has also been found to depend on the orientation. The cage bond dichlorocubane

(5), and N,N-diisopropylcubane-1,4dicarboxamide ( 6) have been investigated by means of X-ray antiperiplanar to the methyl group is shortened, while the cage bonds in gauche orientation to this group are diffraction analysis. Fluorine and chlorine substituents cause a shortening of the vicinal bonds, as is seen in the 4-lengthened. As seen in the case of the halogen-substituted derivatives, the bonds bearing the acetoxy substituent are halocubane-1-carboxylates. The cage bonds vicinal to the ester substituent, with a favorable orientation with regard to shortened due to the σ-acceptor property of this group. Ab initio calculations on compounds 1, 2, 4, and 5 performed at the π-acceptor influence of this group become longer than the CH-CH bonds. Furthermore, the influence on bond the 6-31G* level confirm the experimental results.

into the twofold acid chloride and subsequent solvolysis Im Neuenheimer Feld 253, D-69120 Heidelberg, Germany with diisopropylamine yielded N,N-diisopropylcubane-1,4-