Univ. Bordeaux, ISM (CNRS-UMR 5255) and IECB, 2 rue Robert Escarpit, 33607 Pessac Cedex (France).
Angew Chem Int Ed Engl. 2014 Sep 8;53(37):9860-4. doi: 10.1002/anie.201403571. Epub 2014 Jul 22.
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 and iodobiphenyls, their successful and selective DMDO-mediated oxidation into either λ(3)- or λ(5)-iodanes, and the evaluation of their capacity to promote asymmetric hydroxylative phenol dearomatization (HPD) reactions. Most notably, a C2-symmetrical biphenylic λ(5)-iodane promoted the HPD-induced conversion of the monoterpene thymol into the corresponding ortho-quinol-based [4+2] cyclodimer (i.e., bis(thymol)) with enantiomeric excesses of up to 94%.
长期以来，人们一直致力于寻找手性高价碘烷化合物（即碘烷）作为无金属试剂用于不对称合成。尽管最近在使用化学计量的末端氧化剂的有机碘催化反应中取得了显著进展，但仍然需要“可瓶化”的手性碘烷试剂。本文描述了新型碘联萘和碘联苯的合成，它们成功且选择性地被 DMDO 介导氧化为 λ(3)-或 λ(5)-碘烷，并评估了它们促进不对称羟基化苯酚去芳构化（HPD）反应的能力。值得注意的是，C2 对称联苯 λ(5)-碘烷促进了单萜香芹醇的 HPD 诱导转化，生成相应的邻醌基 [4+2] 环二聚体（即双香芹醇），对映过量高达 94%。
