New chromenochalcones from Flemingia

An Efficient and Concise Synthesis of Biologically Interesting Natural Flemichapparin A, Flemingin A, Flemingin D, and Their Non-natural Analogues

“…The spectral data of our synthetic materials 5 and 8 are the same as values reported in the literature. 6,8 In conclusion, the efficient and concise total synthesis of biologically interesting pyranochalcone natural products flemichapparin A (1), flemingins A (5) and D (8), and their non-natural anogues 2-4. The key strategy in the synthetic procedures involves the ethylenediamine diacetate-catalyzed benzopyran formation and the aldol reactions.…”

“…Similarly, reactions of 24 with aldehydes 25 and 26 afforded products 28 and 29 in 75 and 79% yields, respectively. Deprotection of 28 and 29 with 3 N HCl afforded flemingins A (5) and D (8) in 82 and 87% yields. The spectral data of our synthetic materials 5 and 8 are the same as values reported in the literature.…”

“…7 Flemingin D (8) was isolated from Flemingia congesta. 8 Although a few synthetic methods to flemicharpparin A (1) and flemingin A derivatives have been reported, these synthetic approaches have been limited due to many reaction steps, harsh reaction conditions, and low yield involving side reactions. 9 In particular, no convergent total syntheses of flemingin A (5) and D (8) are unknown.…”

“…As part of an ongoing examination of the synthetic efficacy of this methodology, we investigated ethylenediamine diacetatecatalyzed condensation of 2,4,5-trihydroxyacetophenone with 3-methyl-2-butenal and citral to yield benzopyranes. Using synthesized benzopyrans as a key step, we report herein an efficient and rapid synthetic routes to biologically interesting natural flemichapparin A (1), flemingins A (5) and D (8), and their non-natural anogues 2-4.…”

Reactions of o-quinones with some bis-phosphonium salts in the presence of lithium ethoxide

“…C26H,60 requires C, 90.67; H, 4.68%); v, , , . (Nujol) 3 440, 3 060, 1 620, 1 590, 1 205, 1 077, 1 025, 860, 820, 760, and 750 cm-'; h,,,,(CHCl,) 256sh, 273sh, 301sh, 311, 323, 338sh, 357, and 408sh nm (log E 4.62, 4.32,4.16, 4.03, 4.18, 3.91, 3.60, and 3.26); G(CDC1,) 8.82-8.30 (3 H, m), 7.98-7.12 (12 H, m), and 5.98 (1 H, br s); m/z 345 (24%), 344 ( M + , loo), 343 (36), 342 (59), 327 (7), 326 (5), 316 (ll), 315 (33), 314 (16), 313 (38), 172 (3, and 163 (8).…”