Organic Letters最新文献

Trimeric phthalides in nature are rarely reported. This research successfully isolated three novel trimeric phthalides, triangesinenolides A-C (1-3), from Angelica sinensis. These compounds, derived from Z-ligustilide via diverse linkage patterns, display intricate polycyclic skeletons. Their structures were confirmed by spectroscopic and crystallographic analyses. Unlike previously identified trimeric phthalides, triangesinenolide C (3) is the first trimeric phthalide synthesized via [2 + 2]/[4 + 2] cycloaddition. In vitro assays evaluated the anti-renal fibrosis activity of trimeric phthalides for the first time.

The selective release of a molecule in its native form from a constructed framework is very attractive in the chemical and biological fields. The amide bond is ubiquitous in biological and chemical systems. However, the cleavage of an unmodified typical amide is a great challenge because of its high level of stabilization. Here, couplings of 8-azido-1-naphthoic acid prepared by us with amines afforded 8-azido-1-naphthamides. Reductions of 8-azido in 8-azido-1-naphthamides with sodium sulfide yielded 8-amino-1-naphthamides, and then, fast intramolecular nucleophilic attack of 8-amino to carbonyl of 1-amido in the presence of silica gel as the additive afforded 2,3-benzo[cd]indol-2(1H)-one freeing amines in almost quantitative conversion rates for the ipsilateral effect of 1,8-substituents on naphthalene. Furthermore, this strategy was extended to the cleavages of esters (alkyl 8-azido-1-naphthoates) successfully. The cleavages of amides and esters were performed in an aqueous medium at room temperature with wide functional group tolerance and were suitable for gram-scale production.

The functionalization of N-acylsulfenamides is a research focus in organosulfur chemistry, as the N-S array has unique properties and versatile applications. Although great progress has been made in S-functionalization, the N-functionalization, especially the N-arylation of N-acylsulfenamides, has rarely been explored because of the lower nucleophilicity of the N-site. Herein, we report a Brønsted acid-catalyzed regioselective N-arylation reaction of N-acylsulfenamides with o-quinone diimides. Under mild and metal-free conditions, a wide range of N-arylated N-acylsulfenamides have been prepared in good yields with excellent regioselectivity. The ease of gram-scale synthesis and transformations into useful sulfonamides demonstrates their synthetic practicality.

Despite progress in ortho C-H functionalization of aromatic rings directed by guiding groups, achieving highly selective hydroxylation in simple systems without the need for additional ligand assistance remains a significant challenge. Here, we report the direct hydroxylation of the ortho C-H bond of aromatic rings directed by quinoline under Cu(II) catalysis. Based on experimental analysis and DFT calculations, the main reason for the high selectivity of the quinoline-directed hydroxylation reaction is that the match between the new substrate and the method leads to an increased range of oxygen source incorporation. Isotope experiments and DFT calculations provide support for the origin of the oxygen source in the hydroxylation process and the rationale behind its observed distribution. Additionally, the introduction of various nucleophiles enabled the cyanation, nitration, and halogenation of ortho C-H bonds in the aryl group.

Hyperforin is considered the flagship congener among polycyclic polyprenylated acylphloroglucinols due to its compelling and complex molecular architecture, coupled with remarkable biological activity, thus rendering it an appealing synthetic target for chemists over the past two decades. Herein, an innovative linear total synthesis of hyperforin is reported. Our synthesis relies on the formation of the bicyclo[3.3.1]nonane-2,4,9-trione framework via transannular acylation of a decorated eight-membered ring, followed by late stage bridgehead substitution.