Synthesis of Tetramic Acid Derivatives via a Tandem Umpolung Alkylation/Reduction/Cyclization Reaction of γ-Hydrazono β-Ketoester

Histone Deacetylase 6 Inhibitor 5-Phenylcarbamoylpentyl Selenocyanide (SelSA) Suppresses Hepatocellular Carcinoma by Downregulating Phosphorylation of the Extracellular Signal-Regulated Kinase 1/2 Pathway

Histone deacetylase 6 (HDAC6) enzyme plays a crucial role in a variety of cellular processes related to cancer, and inhibition of HDAC6 is emerging as an effective strategy for cancer treatment. Although several hydroxamate-based HDAC6 inhibitors showed promising anticancer activities, the intrinsic defects such as poor selectivity, stability, and pharmacokinetics limited their application. In this study, a potent selenocyanide-bearing HDAC6 inhibitor, 5-phenylcarbamoylpentyl selenocyanide (SelSA), was evaluated for its antihepatocellular carcinoma (HCC) activity and further explored for its antitumor mechanisms. In vitro studies demonstrated that SelSA exhibited excellent antiproliferative activity against three HCC cells HepG2 (2.3 ± 0.29 μM), Huh7 (0.83 ± 0.48 μM), and LM3 (2.6 ± 0.24 μM). Further studies indicated that SelSA could downregulate the expression of extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation, inhibit the growth, invasion, and migration of Huh7 cells, and promote their apoptosis. Moreover, SelSA significantly suppressed tumor growth in Huh7 xenograft mouse models. Our findings suggest that SelSA could be a potential therapeutic agent for HCC.

Umpolung Chemo- and Regioselective Cascade Addition of Diethylzinc to α-Diketones Followed by Intramolecular Michael Reaction: Stereoselective Synthesis of Highly Substituted 1- Indanones

Herein we report an efficient stereoselective umpolung 1,2-addition of Et₂Zn onto α-diketones followed by intramolecular cascade Michael cyclization. This strategy effectively delivers a broad range of substituted 1-indanones in excellent yields in a chemo- and regioselective fashion. Additionally, we performed a variety of synthetic transformations on the 1-indanone products. Furthermore, a hitherto-unexplored asymmetric variant of this methodology that provides up to 94:6 er using an easily accessible cinchona alkaloid ligand has been addressed.

Highly Selective Synthesis of α-Aminoamide Utilizing an Umpolung Reaction and Characteristics of α-Hydrazonoester

An umpolung reaction with α-hydrazonoesters was investigated, and it was found that α-N,N-dialkylaminoamides could be directly synthesized in yields up to 92% via a concomitant rearrangement of dialkylamino groups. As an application, a short synthesis of an inhibitor of glycine type-1-transporter was accomplished via subsequent functional group transformations in 28% overall yield.

N-Alkylation/aldol reaction of α-aldimino thioesters: a facile three-component coupling reaction

Theoretical calculation of the reactivity of α-imino thioesters indicates that they are very reactive substrates for Umpolung N-alkylation. In fact, treatment of α-aldimino thioesters with dialkylzinc reagents in the presence of aldehydes or imines gives three-component coupling products in good yields.