CAN-Mediated Oxidations for the Synthesis of Xanthones and Related Products

Abstract

Reaction of (2,4,5-trimethoxyphenyl)(2-hydroxyphenyl)methanone with ceric ammonium nitrate furnished the xanthone, 2,3-dimethoxy-9H-xanthen-9-one. Under the same conditions the related (1,4-dimethoxynaphthalen-2-yl)(2-hydroxyphenyl)methanone resulted in the formation of 12a-methoxy-5H-benzo[c]xanthenes 5,7(12aH)-dione. Other examples of this novel transformation are also outlined.

Total Synthesis of (R,R,R)‐γ‐Tocopherol through Cu‐Catalyzed Asymmetric 1,2‐Addition

“…Vilsmeier–Haack reaction (phosphoryl chloride and DMF),29 Rieche formylation (titanium tetrachloride and dichloromethyl methyl ether),30 and also ortholithiation with n BuLi/TMEDA followed by reaction with DMF31 did not provide significant amounts of 18 . In an alternative approach, using the conditions reported by Fukuyama et al., 16 was first brominated,32 followed by bromo–lithium exchange and reaction with DMF 33. This led after optimization to 18 in an excellent yield from 16 .…”

Mild and Versatile Potassium Fluoride/Tetrabutylammonium Fluoride Protocol for Ester Hydrolysis

“…7a, 7b, 7e, 7f, 7g, 7h, 7i, 7j, 7k and 7l) and the carboxylic acids (8a, 8b, 8e, 8f, 8g, 8h, 8i, 8j, 8k and 8l) mentioned in the Table-1 are commercially known compounds and are confirmed by matching with the authentic compounds. The esters 7c, 7d, 7m, 7n, 7o and the carboxylic acids 8c, 8d, 8m, 8n, 8o are reported in the literature [8][9][10][11][12][13][14][15][16] and are confirmed by matching the analytical data with the authentic compounds. Further the reaction was tried on p-nitromethyl benzoate (7a) in different solvents (Table-2) and the solvent THF was found the best in terms of time and yield of the reaction.…”

Synthesis and Biological Properties of Pharmaceutically Important Xanthones and Benzoxanthone Analogs: A Brief Review.

“…Scheme 1 [33] Scheme 2 [34] Scheme 3 [35] Scheme 4 [36] Scheme 5 [37] Scheme 6 [38] Scheme 7 [38] Scheme 8 [39] Bedi et al Bedi et al…”