Unexpected Extension of Usage of PPh3/CBr4, a Versatile Reagent: Isomerization of Aromatic Allylic Alcohols

Abstract

The PPh3/CBr4-catalyzed isomerization of 2-aromatic allylic alcohols into the corresponding saturated aldehydes or ketones has been achieved at room temperature in good to excellent yields under mild and metal-free conditions. This new methodology has been applied successfully to the synthesis of ibuprofen in four steps.

Synthesis of 2,5-Diaryl-1,5-dienes from Allylic Bromides Using Visible-Light Photoredox Catalysis

“…R f 0.37 (5% ethyl acetate/hexanes); 1 H NMR (500 MHz, CDCl 3 ): δ 7.45 (d, J = 8.8, 2H), 6.91 (d, J = 8.8, 2H), 5.48 (s, 1H), 5.40 (s, 1H), 4.37 (s, 2H), 3.83 (s, 3H); 13 C NMR (125 MHz, CDCl 3 ): δ 159.8, 143.7, 130.1, 127.7, 115.6, 114.0, 55.4, 34.6. Characterization data obtained for 2i matched those previously reported in the literature …”

Light‐Triggered RNA Annealing by an RNA Chaperone

“…Various methods involving coupling the corresponding α‐hydroxyacetophenone with 3 were unsuccessful. Ultimately, the p ‐hydroxyphenacyl group was introduced indirectly via a Mitsunobu reaction between 3 and allyl alcohol 5 13. Nucleoside 1 was obtained from 6 via exhaustive deprotection following transformation of the terminal alkene ( 4 ) into the ketone ( 6 ) via a one‐pot osmylation/periodate oxidation 14.…”

Recent Advances in the Synthesis of Ibuprofen and Naproxen

“…Another synthetic protocol for ibuprofen synthesis is summarized in Scheme 11 [ 48 ]. It was attempted to substitute allylic alcohol 28 by the allylic oxidation of terminal methylene 27 using a simple Appel reaction [ 49 ].…”