Water Mediated Rearrangement of Alkynyl Cyclohexadienones: Access to meta-Alkenylated Phenols

Abstract

We report an efficient water mediated, Brønsted acid-catalyzed rearrangement of alkynyl cyclohexadienones to access meta-olefinated phenols under metal-free conditions. The reaction displayed excellent substrate scope and yields in water. Synthetic utility of the protocol was highlighted by carrying out gram scale synthesis, further functionalizations, and late stage modification. Mechanistic studies highlighted the key role of water, as the reaction proceeds via a water addition–elimination sequence on to a vinyl cation intermediate.

Lewis Acid-Driven Meyer–Schuster-Type Rearrangement of Yne-Dienone

“…To our disappointment, compound 1x (having a methoxy group in the angular position of yne-dienone) decomposed during the course of the reaction. Overall, the present demonstration is comparatively productive and effective over the complementary method . In addition, the electron-rich alkyne-containing yne-dienone delivers the best result; this information supports the involvement of a cationic intermediate in this transformation.…”

“…Despite the broad synthetic transformations uncovered in MSRs, a detailed investigation on the current findings α-arylative MSR is yet to be explored in detail. During the preparation of this manuscript, a silver­(I)-catalyzed and TfOH-mediated cyclization-aromatization cascade of alkyne-tethered-cyclohexadienone has recently been appeared …”

A metal-free four-component sulfonylation, Giese cyclization, selenylation cascade via insertion of sulfur dioxide

“…12 Our group has had a long standing interest in the study of alkynyl cyclohexadienones. 13 Along this, we had reported a visible-light mediated synthesis of sulfenylated dihydrochromenones, wherein a sulfenyl radical underwent Giese type cyclization (Scheme 1a, left). 13 a Subsequently, we also demonstrated a Pd-catalyzed regioselective synthesis of bis -halogenated dihydrobenzofuranones (Scheme 1a, right).…”

Accessing meta-Enone-Substituted Anisoles using ArN2BF4 as Precatalyst via Rearrangement of Alkyne-Tethered Cyclohexadienones

“…2 New developments of arene diazonium compounds are still emerging persistently. 3 Aryldiazonium salt of tetrafluoroborate was also recently employed as a potential Lewis acid catalyst for some benchmark reactions. 4 Fluoroboric acid is very common acid in chemical laboratories that has diverse application in organic synthesis.…”