In this report, we establish that
DM-Segphos copper(I) complexes
are efficient catalysts for the enantioselective borylation of para-quinone methides. This method provides straightforward
access to chiral monobenzylic and dibenzylic boronic esters, with
enantiomeric ratios up to 96:4, using a commercially available chiral
phosphine. Standard manipulations of the C–B bond afford a
variety of chiral diaryl derivatives.
Suggesting novel disconnections: A powerful Ni-catalyzed cascade reaction involving cyclization followed by cross-coupling allows the formation of up to three alkyl-alkyl bonds in a single operation by using alkene-containing alkyl iodides and Grignard reagents (see scheme; acac = acetylacetonate; TMEDA = N,N',N'-tetramethyl ethylenediamine). Mechanistic experimental and computational studies suggest a Ni(I)-Ni(II)-Ni(III) catalytic cycle and the intermediacy of radicals.
A straightforward access to polyhydroxylated terpenoids based on two key titanocene(III)-mediated reactions is presented: the "head-to-tail" Barbier-type addition of prenyl chlorides to α,β-unsaturated aldehydes, which allows the introduction of hydroxy groups at desirable positions of the acyclic precursor, and the subsequent bioinspired radical cyclisation. This methodology has been also used in the first total synthesis of pentacyclic sesterstatin 1 and a model compound of the C-D rings of aspergilloxide.
Reaction of a variety of 1,7-enynes with bis(pinacolato) diboron catalysed by Pd bis(trifluoroacetate) affords homoallylic and allylic boronates containing a six membered carbo- or heterocycle, by formation of C-C and C-B bonds.
The formation of catalytically active alkyl-Ni(I) complexes by comproportionation of diorgano-Ni(II) precursors and Ni(0) species proceeds easily through triplet states by alkyl ligand exchange. The process involves inversion of the...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.