Indolizine alkaloid

The same principle of sequential cyclopentene-opening RCM resulting in the formation of a dihydropyrrole ring was the key step in Blechert s novel approach to the polyhydroxylated indolizine alkaloid (-)-swainsonine (378) via RRM of 375 (Scheme 73) [157]. 

Castanospermine (67) Indolizine alkaloid MX-3253 (formerly MBI-3253 Celgosivir 6-0-butanoyl castanospermine) (68) Antiviral [Hepatitis C virus (HCV)] Inhibits a-glucosidase I Phase 11 MIGENIX (received license from Virogen Ltd., UK) 577-581... 

The mass spectra of indolizine alkaloids have been reviewed in detail (B-75MI30800). Some principles may be taken from the fragmentation pattern of slaframine, given in Scheme 3. 

Comins, D. L. LaMunyon, D. H. Chen, X. Enantiopure N-acyldihydropyridones as synthetic intermediates asymmetric synthesis of indolizine alkaloids (-J-205A, (-J-207A, and (-J-235B./. Org. Chem. 1997, 62, 8182-8187. Padwa, A. Muller, C. L. Rodriguez, A. Watter-son, S. H. Alkylation reactions of3-(phenyl-sulfonyl) methyl substituted cyclopentanones. Tetrahedron 1998, 54, 9651-9666. 

On deprotection, followed by neutralization, the acetal 190 rearranges spontaneously to the azasugar 191 [153], an analog of the indolizine alkaloids for which synthetic approaches starting from carbohydrates [154] have recently been described [155] employing the olefin... 

Several perhydropyrrolo[l,2-c]oxazoles, such as (234), described by Overman et al. in the context of synthesis of indolizine alkaloids, can be transformed into perhydroindolizines (235) by treatment... 

Myrmicarins. Pyrrolo[2,l,5-cd]indolizine alkaloids from the poison gland secretion of the African mtMyr-micaria opaciventris e.g., the monomeric M. 213 B (1) heptacyclic M. 430 A (2), and the most complex... 

The earliest application of inverse-detected 2D NMR techniques to a terrestrial alkaloid of which we are aware was the assignment of the H and NMR spectra of the indolocarbazole alkaloid staurosporine (7) reported by Meksuriyeri and Cordell (1988). Later in 1988, Edwards et al. utilized HMQC in the elucidation of the structure of pumiliotoxin-A (10) and related indolizine alkaloids isolated from Panamanian poison frogs. These were the only applications of inverse-detected 2D NMR techniques in alkaloid to appear in 1988. We will thus begin with staurosporine (7) and proceed to related carbazole-based alkaloids before continuing to pumiliotoxin-A (10) and other terrestrial alkaloids. 

Digressing, we noted above that the other 1988 application of inverse-detected 2D NMR was to indolizine alkaloids of the pumiliotoxin-A and allopumiliotoxin classes (Edwards et al. 1988). A total of ten alkaloids were... 

Scheme 20.11 Pummerer reaction in the synthesis of indolizine alkaloids.

Jergensen and coworkers reported Cu(OTf)2/t-Bu-BOX (13)-catalyzed Mukaiyama aldol reactions between silylketene acetals and pyridine N-oxide aldehydes (78) and (81) (Scheme 17.16) [21]. The chemical efficiencies were high and good to excellent enantioselectivities were observed. This work further expanded the scope of aldehydes capable of bidentate coordination in aldol reactions. The authors utilized aldol adduct (83) in the synthesis of indolizine alkaloid (84). 

A biogenetically patterned synthesis of the indolizine alkaloid septicine has been reported. The uncommon addition of a jS-keto acid to an imine was the important step which created the bicyclic structure shown in Scheme 119. A neat intramole-... 

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