Chanoclavines

Dehydration. Dehydration of hydroxy fatty acids is quite common. Other compounds undergo the same reaction, eg, elymoclavine [548-43-6] to agroclavine [548-42-5] chanoclavine [2390-99-0] and other compounds and <7j -terpin hydrate [2541-01-63] to a-terpineol [98-55-5] (19). 

Ceroplastol synthesis, 1, 428 Cetyl alcohol synthesis, 1, 478 Chaetoglobasins structures, 4, 376 Chalcone, o -azido-2 -oxy-synthesis, 3, 823 Chalcone, 2-hydroxy-reduction, 3, 751 Chalcone, 2 -hydroxy-mass spectra, 3, 618 Chalcone dibromides flavone synthesis from, 3, 823 Chalcones polymers, 1, 304 Chanoclavine synthesis, 6, 423 Charge density waves in stacks of ions, 1, 351-352 Chartreusin... 

Somei adapted this chemistry to syntheses of (+)-norchanoclavine-I, ( )-chanoclavine-I, ( )-isochanoclavine-I, ( )-agroclavine, and related indoles [243-245, 248]. Extension of this Heck reaction to 7-iodoindoline and 2-methyl-3-buten-2-ol led to a synthesis of the alkaloid annonidine A [247]. In contrast to the uneventful Heck chemistry of allylic alcohols with 4-haloindoles, reaction of thallated indole 186 with 2-methyl-4-trimethylsilyl-3-butyn-2-ol affords an unusual l-oxa-2-sila-3-cyclopentene indole product [249]. Hegedus was also an early pioneer in exploring Heck reactions of haloindoles [250-252], Thus, reaction of 4-bromo-l-(4-toluenesulfonyl)indole (11) under Heck conditions affords 4-substituted indoles 222 [250], Murakami described the same reaction with ethyl acrylate [83], and 2-iodo-5-(and 7-) azaindoles undergo a Heck reaction with methyl acrylate [19]. 

In a related approach, Murakami synthesized clavicipitic acid and costaclavine [79], and later extended this chemistry to a synthesis of chanoclavine-I featuring the intramolecular Heck vinylation 240 to 241 [266], The corresponding enone failed to cyclize under these conditions. Noteworthy is that radical cyclizations, which often compete successfully with Heck reactions, were poor in this system. 

Yang described the Pd-induced cyclization of an aryl bromide onto a pendant cyano group leading to y-carbolines and related compounds [488], Genet studied the use of chiral palladium complexes in the construction of the C-ring of ergot alkaloids, a study that culminated in a synthesis of (-)-chanoclavine I [489-491]. For example, nitroindole 388 is cyclized to 389 in 57% yield and with enantioselectivities of up to 95% using Pd(OAc)2 and (S)-(-)-BINAP. 

Scheme 3. Pd-catalyzed intramolecular asymmetric allylic alkylation in Genet s synthesis of chanoclavine I (1994).

Mothes, K., u. K. Winkler Zur Frage der Biosynthese des Chanoclavins. Tetrahedron Letters [London] 1902, 1243,... 

Stauffacker, D. u. H. Tscherter Isomere des Chanoclavins aus Claviceps purpurea (Fr.) Tul. (Sccale comutum). 63. Mitt, fiber Mutterkornalka-loide. Helv. chim. Acta 47, 2186 (1954). 

Voigt, R., u. M. Bornschein Zur SteUung des Chanoclavins im Alkaloid-stollwecbsel von Claviceps purpurea Tul. Pharmazie 19, 342 (1964). 

Fig. 10 Chanoclavine mannosylation using enzymatic transglycosylation and reversed glycosylation...

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