Asymmetric Hydroxylative Phenol Dearomatization Promoted by Chiral Binaphthylic and Biphenylic Iodanes
作者:Cyril Bosset、Romain Coffinier、Philippe A. Peixoto、Mourad El Assal、Karinne Miqueu、Jean-Marc Sotiropoulos、Laurent Pouységu、Stéphane Quideau
DOI:10.1002/anie.201403571
日期:2014.9.8
The long‐standing quest for chiral hypervalent organoiodine compounds (i.e., iodanes) as metal‐free reagents for asymmetric synthesis continues. Although remarkable progress has recently been made in organoiodine‐catalyzed reactions using a terminal oxidant in stoichiometric amounts, there is still a significant need for “flaskable” chiral iodane reagents. Herein, we describe the synthesis of new iodobinaphthyls
dearomatization of 2‐substituted phenols to either 1,2‐benzoquinols or their cyclodimers, catalyzed by 4,5‐dimethyl‐2‐iodoxybenzenesulfonic acid with Oxone, has been developed. Natural products such as biscarvacrol and lacinilene C methylether could be synthesized efficiently under mild reaction conditions. Furthermore, both the reaction rate and site selectivity could be further improved by the introduction of
Phase-Transfer-Catalyzed Oxaziridine-Mediated Hydroxylative Phenol and Naphthol Dearomatization
作者:Charlotte Grandclaudon、Patrick Y. Toullec
DOI:10.1002/ejoc.201501340
日期:2016.1
ortho-hydroxylation of substituted phenolic substrates is reported. In the presence of a phase-transfer catalyst and a base, N-sulfonyloxaziridines react with phenols to give the corresponding 6-alkyl-6-hydroxycyclohexadienone products in moderate to good yields. The reaction proceeds in fair to good yields and excellent chemoselectivity for 2,6-disubstituted phenols, 1-naphthols, and 2-naphthols.
ortho-quinols could be obtained in high yields (up to 99%) and enantioselectivities (up to 95:5 er). This methodology could be applied in the synthesis of bioactive lacinilenes in a gram-scale reaction. Based on the experimental investigations and previous work, a possible catalytic model was proposed.