Sakai T, Matsuoka J, Shintai M, Mori Y. C
Ar-O Rotamers in 3,3'-Disubstituted BINOL Esters.
J Org Chem 2017;
82:3276-3283. [PMID:
28226205 DOI:
10.1021/acs.joc.6b03035]
[Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Rotamers around the CAr-O bond were disclosed in 3,3'-disubstituted BINOL esters by NMR spectroscopy. A bulky R1 group increased the rotational barrier. The pivalate showed two rotamers at 2 °C, and broad signals were observed close to room temperature when R2 = Ph. The highest rotational barrier was recorded for the (tetracyanocyclopentadienyl)carboxylate, and C-O rotamers were present at room temperature. DFT calculations indicated the presence of repulsion between R1 and R2 during rotation of the CAr-O bond.
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