Chartellines

In addition, there are many important nonantibiotic uses of 2-azetidinones in fields ranging from enzyme inhibition [15-21] to gene activation [22], Systems containing one carbon atom common to two rings, spirocyclic compounds, represent an important structural organization. Spirocyclic p-lactams (Fig. 3) behave as p-tum mimetics [23-26] as well as enzyme inhibitors [27, 28], they are precursors of a,a-disubstituted p-amino acids [29-32], and the spiranic p-lactam moiety is present in chartellines and chartelamides [33-38], a family of marine natural products. Synthetic studies and biosynthetic speculation inspired by an unexpected reaction on the marine alkaloid chartelline C have been described [38],... 

A model compound 15 containing an indole (3-lactam moiety in chartellines was synthesized from the Mannich reaction of isatin imine with ketene silyl acetal, followed by (3-lactam formation through cyclization of the resulting (3-amino acid 14 (Scheme 5) [52]. L-Proline-catalyzed direct asymmetric Mannich reactions of... 

Kajii S, Nishikawa T, Isobe M (2008) Chem Commun 3121, Synthetic studies and biosynthetic speculation inspired by an unexpected reaction on the marine alkaloid chartelline C have been described... 

Scheme 40 Efficient synthesis of indolenine spiro-P-lactams in Chartelline...

Isobe et al. [114] have revealed the novel synthesis of indolenine spiro-p-lactams 173 (Scheme 40) in Chartelline, which belongs to the family of marine natural products. The starting precursors 172 were submitted to cyclization by employing a variety of bases such as EtMgBr, n-BuLi, t-BuOK, LDA, KHMDS, NaHMDS, and LiHMDS in THF at different reaction temperatures. Out of all these bases, LiHMDS at -78°C was found to be the best which provided the exclusive formation of spiro-p-lactams 173 without /V-methylamide 174 as a side product. 

Baran PS, Shenvi RA, Mitsos CA (2005) A Remarkable Ring Contraction En Route to the Chartelline Alkaloids. Angew Chem IntEd 44 3714... 

Unique /3-lactam indole alkaloids, namely, chartellines A (77) (87), B (78), and C (79), methoxydechlorochartelline A (80) (88), and chartella-mides A (81) and B (82) (89), were isolated from a marine bryozoan (Chartella papyracea) collected in North Britanny waters. The structure of chartelline A (77) was confirmed by X-ray analysis, and the absolute... 

Scheme 12. Alkaloids from Chartella papyracea. At left, chartelline A, B, C, and methoxy-dechlo-rochaitelline A. At right chartellamide A and B.

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