Shengping Zheng

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Jaboticaba (Myrciaria cauliflora) and false jaboticaba (Myrciaria vexator) fruits are two pleasant-tasting, dark-colored fruits, native to Brazil. They are rich sources of phenolic compounds, including anthocyanins, flavonoids, phenolic acids, and tannins, as well as less well known polyphenols such as depsides. These two fruits are very similar in(More)
We report the enantioselective total synthesis of cribrostatin IV (1). Key features of this synthesis involve the convergent coupling of two highly functionalized homochiral components followed by a "lynchpin" Mannich cyclization to establish the pentacyclic core (cf. 19 --> 20).
A well-defined nonprecious metal cobalt(II) catalyst based on a pincer PNP ligand has been employed for the efficient N-alkylation of both aromatic and aliphatic amines with alcohols. A subtle change of reaction conditions (simply adding 4 Å molecular sieves) was observed to readily switch the resulting products (amines vs imines) with high(More)
Although a range of nanoparticles have been developed as drug delivery systems in cancer therapeutics, this approach faces several important challenges concerning nanocarrier circulation, clearance, and penetration. The impact of reducing nanoparticle size on penetration through leaky blood vessels around tumor microenvironments via enhanced permeability(More)
Chiral polyamines can be utilized for a variety of potential applications, ranging from asymmetric catalysis to nonviral gene delivery systems for DNA and RNA. They can also be utilized to solubilize carbon nanotubes. Thus, methods for the straightforward synthesis of chiral polyamines are needed. We present herein two synthetic strategies for accessing(More)
An unexpected nucleophilic chlorination of a quinone monoketal while carrying out a pyrazolidine synthesis has led to a general preparation of multisubstituted phenols. The products are obtained in good to high yields under mild conditions. The bridged pyrazolidines that were the original targets are obtained in the presence of a protic solvent.
A general synthesis of bridged isoxazolidines from a double hetero-Michael addition of N-substituted hydroxylamines to quinone monoketals has been developed. The different addition order of N-benzylhydroxylamine and N-Boc hydroxylamine is also discussed. Moreover, the various functionalities in the isoxazolidine products allow facile derivatization.