Alkaloid antifungal

The total synthesis of the antifungal alkaloid K252a has been reported in which the indolocarbazole nucleus is constructed using novel rhodium carbenoid chemistry <1995JA10413, 1997JA9641>. Thus, reaction of 2,2 -biindole with diazolactam 173 in the presence of rhodium acetate in degassed pinacolone produces indolocarbazoles in moderate yields (Equation 107). 

Chiral enamine derivatives have also been used as electron-rich alkenes. The oxazoline derivative 17 reacted with benzaldehyde to yield the two stereoiso-meric oxetanes 18a and 18b with a diastereomeric excess of 67% (Scheme 5) [12]. A significantly higher diastereoselectivity was observed in the case of the reaction of the pyrrolidine derivatives 19 where the enamine function is localized inside the five membered ring [13]. Then the oxetane 20a (R — n-Cgil g) was used in an asymmetric synthesis of the antifungal alkaloid (+ )-preussin. The approach of the 3n,7T excited ketone preferentially occurred syn with respect to... 

Kato et al. [68] reported the isolation and characterization of a novel imidazole antifungal alkaloid, fungerin (33) from the fungus Fusarium sp. The authors employed a GHMBC experiment optimized for 60 ms (8.3 Hz) to establish... 

Antifungal alkaloids from Duguetia hadrantha. Muhammad and co-workers reported the isolation and structural characterization of two alkaloids from Duguetia hadrantha, hadranthine-A and -B (82) that were related to the known alkaloid imbiline-I. To confirm the placement of the annular nitrogen atoms in the skeletal framework, the authors utilized long-range HMBC data. Thus, correlations from protons... 

Zhao W, Wolfender JL, Hostettmann K, Xu R, Qin G. Antifungal alkaloids and limo-noid derivatives from Dictamus dasycarpus. Phytochemistry 1998 47 7-11. 

Hirota, H., Matsuuaga, S., and Fusetani, N. (1990b) Stelletamide A, an antifungal alkaloid from a marine sponge of the genus Stelletta. Tetrahedron Lett., 31, 4163—4164. 

Bach has described an example of unusual facial selectivity in the Paterno-Biichi reaction of chiral dihydropyrrole (230) (Scheme 18.38) [146]. The predominant adduct (231) that was formed featured a cis-relationship between the resident substituents on the heterocycle (n-C<)H,9) and the aldehyde (Ph). This oxetane intermediate 231 was readily elaborated into the antifungal alkaloid preussin (233). 

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