Intramolecular cyclization of phenol derivatives with C C double bond in a side chain

A recyclable copper(ii) catalyst for the annulation of phenols with 1,3-dienes

“…The Lewis acidic copper(II) complex facilitates the aromatic Claisen rearrangment of intermediate I to II, which then undergoes a second hydroalkoxylation to furnish the heterocycle. 11 The proposed mechanism complements the following observations: (1) Product mixtures obtained from 2,3-dimethylbutadiene (Table 2, entries 3 and 11) can be explained by the competitive formation of tertiary carbocations in intermediate II;…”

Hidden Brønsted Acid Catalysis: Pathways of Accidental or Deliberate Generation of Triflic Acid from Metal Triflates

“…The development of metal-catalyzed additions of oxygen nucleophiles to nonactivated alkenes − had seen limited success prior to 2002, ,− but the number of reports on such catalytic hydroalkoxylations (including hydroaryloxylations, if R = aryl; Scheme ), or related hydroacyloxylations, dramatically increased after 2004. ,− Many of the new catalysts are electrophilic metal trifluoromethanesulfonate (triflate) salts that display a similar substrate range and product selectivity profile…”

Aluminum‐Catalyzed Hydroalkoxylation at Elevated Temperatures: Fast and Simple Access to Coumarans and Other Oxygen Heterocycles

“…The search for a specific metal catalyst for hydroalkoxylation [4a, 5-7] of nonactivated alkenes, using the reaction of Scheme 1 as a model reaction, was initiated by a 1998 report on a ruthenium triflate catalyst. [18][19][20] Since then, numerous similar reports on catalysis with ZrCl 4 , [21] Sn(OTf) 4 , [22] Al(OTf) 3 , [23] Cu(OTf) 2 or AgOTf, [24] Ln(OTf) 3 in ionic liquids, [25,26] or with Au(PPh 3 )OTf [27] have appeared. Related catalysts were also reported for the tandem conversion of allyl aryl ethers, via 2-allylphenols to coumarans.…”