Sequential O-Arylation/Lanthanide(III)-Catalyzed [3,3]-Sigmatropic Rearrangement of Bromo-Substituted Allylic AlcoholsWe are grateful for financial support by Takeda Pharmaceutical Company (TPC) Ltd. and by the Natural Sciences and Engineering Research Council (NSERC) of Canada for a Discovery Grant to R.A.B and Alexander Graham Bell Canada Graduate Scholarships M and D3 to T.R.R.
Received: 03 July 2017
Accepted after revision: 28 July 2017
25 August 2017 (eFirst)
Dedicated to the Cardinal Chemist, the inimitable Prof. Victor Snieckus, on the occasion of his 80th birthday
Lanthanide(III)-catalyzed aryl-Claisen rearrangement of substrates bearing halo-substituted allyl groups, specifically 2-bromoallyl aryl ethers, afford ortho-2-bromoallylphenols. Aryl ether substrates were synthesized from brominated allylic alcohols via Mitsunobu reaction, Cu(II)-catalyzed arylation using potassium aryltrifluoroborate salts, or SNAr reaction. Aryl-Claisen rearrangements proceeded in moderate to excellent yields using Eu(III) catalysis. The alkenylbromide functionality remains intact, illustrating the compatibility of synthetically important alkenylhalides during C–O/C–C σ-bond migration processes. Subsequent derivatization of the ortho-2-bromoallylphenol products through O-alkylation or C-arylation/alkenylation via Suzuki–Miyaura cross-coupling demonstrate the potential to access densely-functionalized molecules.