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Published on: May 20, 2019
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Diastereoselective β-hydroxy vinylsulfone isomerizations.
G W O'Neil1, T D Clark1, A P Jones1
1Department of Chemistry, Western Washington University, Bellingham, WA 98225, USA. oneilg@wwu.edu.
Organic & Biomolecular Chemistry
|January 15, 2025
Summary
Vinylic phenylsulfones isomerize to allylic compounds using 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU). Reaction diastereoselectivity increases with steric bulk, favoring the erythro-isomer.
Area of Science:
- Organic Chemistry
- Stereoselective Synthesis
Background:
- Vinylic phenylsulfones are versatile synthetic intermediates.
- Control of stereochemistry in isomerization reactions is crucial for complex molecule synthesis.
Purpose of the Study:
- To investigate the diastereoselective isomerization of β-hydroxy vinylic phenylsulfones.
- To explore the influence of substrate structure on reaction stereoselectivity and yield.
Main Methods:
- Treatment of β-hydroxy vinylic phenylsulfones with 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU).
- Analysis of diastereomeric ratios using Nuclear Magnetic Resonance (NMR) spectroscopy.
- Isolation and yield determination of the allylic phenylsulfone products.
Main Results:
- Diastereoselective isomerization to allylic phenylsulfones was achieved.
- Stereoselectivity increased with the steric bulk of the substituent on the carbinol carbon, reaching >20:1 dr for tert-butyl.
- Isolated yields ranged from 59-66%, with C-C bond cleavage as a competing pathway.
Conclusions:
- DBU-mediated isomerization provides a stereoselective route to allylic 1,2-hydroxy phenylsulfones.
- Steric effects play a significant role in controlling the diastereoselectivity of the isomerization.
- The erythro-isomer is consistently favored, indicating a predictable stereochemical outcome.
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