Conformations of [m.3.3]Propellane Ketones and Alcohols

Anand Natrajan, Joseph D. Ferrara, John D. Hays, Mahesh Khot, Jennifer Colonell, Wiley J. Youngs, Chaim N. Sukenik

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

We have prepared a series of [m.3.3]propellanediones (m = 3, 4, 10, 12, 22) and have studied various structural aspects of these diones and their ketol and diol reduction products. We have used X-ray crystallography to establish stereochemistry and to explore cyclopentyl ring conformations. The 1H NMR spectra of the ketols and diols have also been used to probe their conformations. They provide evidence for intramolecular hydrogen bonding between the OH groups of some of the anti,anti (aa) diols. The folding needed for this interaction is also seen in the gas phase in the j-C4H10 CIMS. For an aa diol, this leads to a bridged [M + 1]+ ion. For an anti ketol, it promotes an intramolecular proton transfer leading to H2O elimination from the [M + 1]+ ion. This results in unusual stability for the protonated parent ion of an aa diol and enhanced fragmentation of the parent ion of an anti ketol, relative to their stereoisomers. The ease of the molecular puckering that is the key observation of both the NMR and CIMS work, is shown to be dependent on the size of the propellane polymethylene bridge.

Original languageEnglish
Pages (from-to)2164-2169
Number of pages6
JournalJournal of Organic Chemistry
Volume55
Issue number7
DOIs
StatePublished - 1990
Externally publishedYes

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