Hongchao Guo

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The phosphine-mediated [3 + 3] annulations of aziridines and allenes are experimentally simple reactions, run under very mild conditions, for the preparation of highly functionalized tetrahydropyridines in yields of up to 98% and trans/cis ratios of up to 97:3. In addition to steps that are typical of nucleophilic phosphine-catalyzed reactions of(More)
The COP9 signalosome has been implicated in pluripotency maintenance of human embryonic stem cells. Yet, the mechanism for the COP9 signalosome to regulate pluripotency remains elusive. Through knocking down individual COP9 subunits, we demonstrate that Cops2, but not the whole COP9 signalosome, is essential for pluripotency maintenance in mouse embryonic(More)
Members of a new family of chiral triskelion P ligands, namely helical C(3)-symmetric monophosphites P(OR)(3), have been prepared in two steps by monoacylation of (R)- or (S)-1,1'-binaphthyl-2,2'-diol (BINOL) or diphenol using a carboxylic acid chloride followed by PCl(3) phosphorylation. The most sterically hindered member of these monophosphites, derived(More)
This review discusses the tertiary phosphines possessing various chiral skeletons that have been used in asymmetric nucleophilic organocatalytic reactions, including annulations of allenes, alkynes, and Morita-Baylis-Hillman (MBH) acetates, carbonates, and ketenes with activated alkenes and imines, allylic substitutions of MBH acetates and carbonates,(More)
In this paper we describe the phosphine-catalyzed [3 + 2], [3 + 3], [4 + 3], and [3 + 2 + 3] annulations of azomethine imines and allenoates. These processes mark the first use of azomethine imines in nucleophilic phosphine catalysis, producing dinitrogen-fused heterocycles, including tetrahydropyrazolo-pyrazolones, -pyridazinones, -diazepinones, and(More)
The Cu(I)-catalyzed highly enantioselective [3 + 3] cycloaddition between two different 1,3-dipoles, phthalazinium dicyanomethanides and iminoester-derived azomethine ylides, has been achieved under mild reaction conditions, providing novel chiral heterocyclic compounds, 2,3,4,11b-tetrahydro-1H-pyrazino[2,1-a]phthalazine derivatives, in high yields with(More)
Much progress has been made in designing heme and dinuclear nonheme iron enzymes. In contrast, engineering mononuclear nonheme iron enzymes is lagging, even though these enzymes belong to a large class that catalyzes quite diverse reactions. Herein we report spectroscopic and X-ray crystallographic studies of Fe(II)-M121E azurin (Az), by replacing the axial(More)
An enantioselective synthesis of pharmaceutically important spirobarbiturates has been achieved via spirocyclic chiral phosphine-catalyzed asymmetric [4 + 2] annulation of barbiturate-derived alkenes with allenoates. With the use of this tool, various spirobarbiturate-cyclohexenes are obtained in good to excellent yields with excellent diastereo- and(More)
The previously reported concept of using mixtures of monodentate ligands in a combinatorial manner in order to influence enantio- or regioselectivity of transition metal catalyzed processes has been extended to include diastereoselectivity. Accordingly, 1,2- and 1,3-asymmetric induction in the Rh-catalyzed hydrogenation of a chiral allylic alcohol and a(More)