Alkyl and alkoxycarbonyl radicals were generated by oxidative decarboxylation of oxalic acid monoesters by persulfate; they were then utilized for the selective substitution of quinones.
Organocatalytic Enantioselective Synthesis of Atropisomeric Aryl‐
<i>p</i>
‐Quinones: Platform Molecules for Diversity‐Oriented Synthesis of Biaryldiols
作者:Ye‐Hui Chen、Heng‐Hui Li、Xiao Zhang、Shao‐Hua Xiang、Shaoyu Li、Bin Tan
DOI:10.1002/anie.202004671
日期:2020.7.6
Presented here is a class of novel axiallychiral aryl‐p ‐quinones as platform molecules for the preparation of non‐C2symmetric biaryldiols. Two sets of aryl‐p ‐quinone frameworks were synthesized with remarkable enantiocontrol by means of chiral phosphoric acid catalyzed enantioselective arylation of p ‐quinones by central‐to‐axialchirality conversion. These aryl‐p ‐quinones were then used to access
axially chiral biaryldiols via asymmetric Friedel–Crafts aromatization between p-quinones and 2-naphthols was developed. A chiral cobalt(II) complex of N,N′-dioxide enabled the process to generate axially chiral biaryldiols in up to 98% yield and 95% ee. A large range of substituents at different positions of p-quinones and 2-naphthols was tolerable. The configuration of the product and the chiral N,N′-dioxide-Co(ClO4)2
The catalytic enantioselective [2+2] cycloaddition between quinones and fulvenes was achieved, for the first time, by the use of a chiral copper(II) complex catalyst. The transformation afforded a series of enantiomerically enriched [6,4,5]-tricyclic cyclobutane derivatives in good yields with excellent regio- and stereoselectivities. Furthermore, the [2+2] adducts could be easily converted into formal
A catalytic asymmetric one-pot [3+2] cyclization/semipinacol rearrangement sequence: an efficient construction of a multi-substituted 3<i>H</i>-spiro[benzofuran-2,1′-cyclopentane] skeleton
facile and efficient method to form a chiral multi-substituted 3H-spiro[benzofuran-2,1′-cyclopentane] structural unit has been developed via a one-pot [3+2] cyclization/semipinacol rearrangement cascade. A catalysis system of Cu(II)/BOX has been used to efficiently construct a key stereogenic center via a cyclization between substituted benzoquinones and allylic alcohols affording the desired products