Enantioselective Total Synthesis of Cyathin A₃.

Abstract

The cyathins are a unique group of diterpenoids produced by the bird's nest fungi Cyathus helenae, C. africanus, and C. earlei In Section 2.2, the enantioselective Diels-Alder reaction of quinone 106 and diene 105 is presented. This reaction is effectively catalyzed by a carefully iii prepared Mikami catalyst. It was carried out on a preparative scale to give the chiral building block 108. The absolute configuration of the Diels-Alder adduct 108 was determined by NMR and X-ray analysis.

Enantioselective total synthesis of (−)-cyathin B2

“…The tert-butyldiphenylsilyl (TBDPS) group in 10 was removed by TBAF; the oxidation of the resultant primary alcohol group with Dess-Martin periodinane reagent afforded the final product, 1. The 1 H NMR, 13 C NMR, IR and HRMS spectral data of 1 completely matched with those reported by Ayer and Lee 1 and Kim and Cha, 16 thus confirming the formation of 1. They did not report the [a] D and melting point of 1 because Cha and co-workers reported the total synthesis of racemic cyathin B 2 ; therefore, herein we report the [a] D and melting point of 1 for the first time.…”

“…For example, (À)-erinacine E and (À)-scabronine A are the potent stimulators of nerve growth factor synthesis; moreover, (À)-erinacine E is a selective agonist of the k-opioid receptor and a promising substitute for morphine. 2 The therapeutic relevance and synthetic challenges of cyathane diterpenoids have attracted great attention over the past decade, and numerous synthetic studies as well as total syntheses of cyathane diterpenoids and congeners have been reported, [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] and review articles have been published. 20 Although the structure of 1 is relatively simple and its biological activity is moderate, the total synthesis of 1 involves a basic problem that needs to be solved, that is, the efficient construction of the cyathane core that would enable the total syntheses of other cyathane diterpenoids with potent biological activities.…”

Alkaline Earth Metal–Organic Frameworks Based on Tetratopic Anthraquinone-Based Linkers: Synthesis, Characterization, and Photochemical Applications

“…The product was isolated as a deep dark red solid (1.3 g, 100% yield). 1 Mg Metal−Organic Framework (5). 4 (35.0 mg, 0.05 mmol) was fully dissolved in 10 mL of DMF in a sealable glass vial to yield an orange solution.…”

“…The crude product was vacuum filtered, thoroughly washed with H 2 O and EtOH, until the alcoholic washing was colorless. Finally, the solid was dried at 100 °C overnight to yield 1.052 g of 2.1 (2.87 mmol, 91% yield) as a pale brown powder 1. H NMR (400 MHz, CDCl 3 ): δ 8.44 (d, 4 J = 1.6 Hz, 2H), 8.17 (d, 3 J = 8.1 Hz, 2H), 7.94 (d, 3 J = 9.8 Hz, 2H) ppm.…”

“…1 H NMR (400 MHz, CDCl 3 ): δ 8.14 (d, 2H, 3 J = 8.6 Hz) 8.02 (d, 8H, 3 J = 8.8 Hz) 7.90 (d, 2H, 4 J = 2.4 Hz) 7.37 (dd, 2H, 3,4 J = 8.6, 2.4 Hz) 7.18 (d, 8H, 3 J = 8.8 Hz) 4.39 (q, 8H, 3 J = 7.1…”