Asymmetric total synthesis of rhinacanthin A

Aryne Precursors for Selective Generation of 3-Haloarynes: Preparation and Application to Synthetic Reactions

The synthesis and reaction of new 3-haloaryne precursors 2a-2h were studied. The ortho-(trimethylsilyl)aryl triflate precursors 2a-2h were prepared by a simple procedure involving O-trimethylsilylation and migration of a trimethylsilyl group followed by triflation. The remarkable feature of new precursors is the selective generation of 3-haloarynes by suppressing the competitive thia-Fries rearrangement, which is the problem in the reaction using the well-known 3-haloaryne precursors. The advantage of new precursor 2a over a typical precursor 1 was confirmed by the direct comparisons in several reactions. The application of precursors 2a-2h to the syntheses of heterocycles was also reported.

The anionic Fries rearrangement: a convenient route to ortho-functionalized aromatics

The scope and mechanism of anionic (hetero-) Fries rearrangements are summarized for various migrating groups and arenes, including applications and computational studies.

Isolation and Identification of Benzochroman and Acylglycerols from Massa Medicata Fermentata and Their Inhibitory Effects on LPS-Stimulated Cytokine Production in Bone Marrow-Derived Dendritic Cells

Massa Medicata Fermentata (MMF), known as Shenqu, is an important traditional Chinese medicine widely used to treat indigestion, vomiting, and diarrhea. In this study, a new benzochroman, 3(S)-3,4-dihydro-5,10-di-β-d-glucopyranoside-2,2-dimethyl-2H-naphtho(2,3-b)pyran-3-ol (1), and five known galactosyl acylglycerols (2–6) were isolated from a methanol extract from MMF. In addition, their chemical structures were determined by chemical and spectroscopic methods, which were compared with the previously reported data. Furthermore, the effects of isolated compounds on lipopolysaccharide (LPS)-stimulated bone marrow-derived dendritic cells were investigated. Compounds 1–3 exhibited significant inhibitory effects on the LPS-induced production of IL-6 and IL-12 p40, with IC₅₀ values ranging from 1.6 to 10.2 μM. Compounds 2 and 3 also exhibited strong inhibitory effects on the LPS-stimulated production of TNF-α with IC₅₀ values of 12.0 and 11.2 μM, respectively. The results might provide a scientific basis for the development of the active components in MMF, as well as for novel anti-inflammatory agents.

First Synthesis of 1,4-Dimethoxy-2-Naphthoxyacetic acid

2-Acetyl-1-hydroxynaphthalene was converted into 1,4-dimethoxy-2-naphthoxyacetic acid in seven steps (methylation, Bayer-Villiger oxidation, hydrolysis, bromination, methylation, alkylation and hydrolysis). 2-Hydroxy-1,4-naphthoquinone on acetylation, aromatization, methylation and hydrolysis, respectively, also yielded the title compound.

Chiral squaramide-catalyzed asymmetric synthesis of pyranones and pyranonaphthoquinones via cascade reactions of 1,3-dicarbonyls with Morita-Baylis-Hillman acetates of nitroalkenes

Cascade reactions of 1,3-dicarbonyls with Morita-Baylis-Hillman acetates of nitroalkenes using a quinine derived chiral squaramide organocatalyst led to the formation of pyranones and pyranonaphthoquinones in good to excellent yields and high diastereo- and enantioselectivities. Representative examples of the reaction scale-up with a much lower catalyst loading without an appreciable loss of selectivities and synthetic transformations of the products are also reported here. The compounds described herein for the first time were evaluated against the infective bloodstream form of Trypanosoma cruzi, the etiological agent of Chagas disease, since the structures are related to bioactive α-lapachones.