Conformational Shift by Mutual Steric Interactions between Two Multiarmed Units

Naama Zuaretz, Oren Golan, Silvio E. Biali*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Decakis(bromomethyl)biphenyl (3) has been prepared by reaction of decamethylbiphenyl with Br2/CCl4 in the presence of tetrabutylammonium bromide as catalyst. The attempted synthesis of decakis(bromomethy)benzophenone resulted only in bromopentakis(bromomethyl)benzene (8). X-ray diffraction of a single crystal of 3 shows that the preferred conformation of 3 is not the alternate “up-down” conformation observed for the parent hexakis(bromomethyl)benzene, but a conformation in which the up-down alternation of the CH2Br groups is disrupted at the meta-para positions of each ring. MM2(85) calculations on 3 indicate that some conformations with disrupted “up-down” alternation of the CH2Br groups are favored over the all-alternate up-down form. It is suggested that this conformational shift is the result of the mutual steric interactions between arms of different moieties, and that syn interactions between m- and p-CH2Br groups operate in order to avoid bromine contacts between ortho groups at different rings. The barrier for Ar-CH2Br rotation was estimated from dynamic NMR data as 12.5 kcal mol-1.

Original languageAmerican English
Pages (from-to)2444-2449
Number of pages6
JournalJournal of Organic Chemistry
Issue number7
StatePublished - 1 Mar 1991


Dive into the research topics of 'Conformational Shift by Mutual Steric Interactions between Two Multiarmed Units'. Together they form a unique fingerprint.

Cite this