Tropone alkaloids

A synthesis of tropone alkaloids has been reported which includes the cycloaddition of 1, l,3,3-tetrabromopropan-2-one to N-methoxycarbonylpyrrole in the presence of iron nonacarbonyl. ... 

Rings Containing Nitrogen.— The a-position of saturated nitrogen heterocycles may be activated to subsequent C—C bond formation through anodic oxidation, and this method makes tropone alkaloid precursors (217) readily accessible. The synthesis of various 8- and 9-membered lactams is now possible from... 

The chemistry of 3-oxidopyridinium betaines has been extensively studied notably by Katritzky and Dennis in the late 1970s and early 1980s, who have applied their cycloaddition to the synthesis of core fragments of tropone alkaloids and related natural products [2b]. A major advantage of these cycloaddition reactions results from the... 

A RCM-ROM-RCM strategy was employed as the key step to the synthesis of these alkaloids (Scheme 10). Both alkaloids can be derived from the protected bis-hydropyrrole 31 which is the ring rearranged product from the seven-membered carbocycle 32. Compound 32 can be obtained from the enantiomerically pure triol derivative 33, which in turn can be obtained from commercially available tropone 34.34... 

An isoquinoline system condensed to a tropolone is the skeleton for a tropoloisoquinoline alkaloid. The general structure of the five alkaloids of this type known so far are derivatives of the tautomers of 10-hydroxy-9H-azuleno[l,2,3-i,j]isoquinolin-9-one (42) and 9-hydroxy-10H-azuleno[l,2,3 i,j]isoquinoline-10-one (43) [88]. Recently, the first tropone-isquinoline alkaloid, pareitropone (44) has been isolated from the roots of the South American Menispermaceae, Cissampebs pareira [48]. 

The name tropyliwn and other related names such as tropone CH) and tropolone (HI), which are in normal usage for these cycloheptatriene derivatives, derive from the historic name of cycloheptatriene, namely tropilidine. This in turn comes from tropine (IV), which is a breakdown product of the alkaloid atropine, obtained from deadly nightshade (Atropa belladonna), and from which cycloheptatriene was first prepared, using a series of exhaustive methylation steps [4],... 

The acyllactone rearrangement has been simplified by using exchange resins instead of mineral acids as catalysts Extension of this type of rearrangement to acyllactams gives a variety of pyrrolidine and piperidine derivatives related to alkaloids For the preparation of -pyrrolines andzl -piperideines,a new method has been found Easy access to 1-oxa- and 1-aza-azulene derivatives from tropones has been accomplished... 

A total synthesis of the dipyrrolidine alkaloid (—)-trans-dendrochrysine (22), isolated from the orchid endemic Dendrohium chrysanthum, was achieved by Blechert and coworkers utilizing RRM [21]. The asymmetric synthesis commenced with preparation of diolefin 20 from commercially available tropone (19, Scheme 2.6) in 11 steps involving a solid-phase supported Candida antarctica lipase B (Cal-B)-mediated desymmetrization. 

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