Dihydrocorynantheine structure

Hirsutine (85) is a corynantheine-type indole alkaloid with a C/D cis ring juncture (pseudo stereochemistry). This compound has recently been found to exhibit highly potent inhibition of the replication of the strains of influenza A (subtype H3N2) [63]. The EC50 of hirsutine was 11- to 20-fold more potent than that of the clinically used ribavirin. Exploration of the important structural features of this molecule revealed that the stereochemistry at C-3 (.R) and C-20 (R) as well as the presence of the Nb lone pair were essential for the anti-influenza A activity. Thus, the C-3 epimer, dihydrocorynantheine (86) (normal stereochemistry), was much less active than hirsutine (85). 

Dihydrocorynantheine (86), in turn, along with other structurally related alkaloids, has been found to decrease specific [3H]-5-hydroxytryptamine (5-HT) binding to membrane preparations from rat... 

The total structures of this alkaloid (XCVIIIa) and its dihydroderivatives (XCVIIIb) as well as a synthesis of the former have been reviewed (Vol. VII, p. 42). In the meantime, a total synthesis of dl-dihydrocorynantheine (Cllb) has been reported (69,70). 

Most information regarding the action of alkaloids relates to the alpha 2 receptor, where the indole alkaloids yohimbine and its isomer, rauwolscine, bind with high affinity and block the receptor [187, 191]. Dihydrocorynantheine, an indole alkaloid of similar structure preferentially binds to the alpha 1 receptor, as do some aporphines [192,... 

Dihydrobumamicine has been synthesized (Chart V) but could not be compared (32) with the same derivative of the natural product because none of the latter remained from structural studies (33). The action of lead tetraacetate in benzene transformed dihydrocorynantheine into 7-acetoxy-7H-dihydrocorynantheine (XXVI mp 180°-181°) which was converted into its methiodide (mp 206° decomp.). Hydrolysis of the methiodide in refluxing aqueous acetic acid containing sodium acetate gave the 2-acylindole XXVII (mp 153°-155° or 208°-209°) which gave the expected UV-spectrum in ether but in a more polar solvent (ethanol)... 

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