Lagerstroemia subcostata

We use the name demethyllasubine-I and -II for quinolizidols 64a and 65b. b a, Heimia salicifoiia Link and Otto b, Lagerstroemia subcostata Koehne. 

Fuji et al. (16) have recently isolated lasubine-I (64b) and lasubine-II (63b) from Lagerstroemia subcostata Koehne. The structures of these alkaloids have been established by correlation with synthetic compounds (63a and 64a) as well as by analysis of IR, PMR, 13C-NMR, and mass spectra. These alkaloids are listed in Table IV (16, 47, 48, 50, 51). 

Two minor ester alkaloids, subcosine-I (69) and subcodine-II (67), have been isolated recently by Fuji et al. (16) from Lagerstroemia subcostata. 

Lagerstroemia subcostata Koehne/Subcostata crape myrtle 73 37 17 27 18 7 4 1.5 1.4... 

Isol. from leaf tannin of Lagerstroemia subcostata. [a] -1-40.8° (c, 1 in HjO). Exact struct, unknown. 

The phenylquinolizidine alkaloids lasubine I and lasubine II were obtained from the leaves of Lagerstroemia subcostata as major alkaloids, together with the ester alkaloids subcosine I and subcosine II. These alkaloids are considered to be intermediates in the biogenetic route of the lactonic alkaloids. Thus, lysine, phenylalanine, and a C2 unit (acetate) produce the phenylquinolizidine alkaloids. These are then esterified with another phenylalanine unit to the ester alkaloids, followed by conversion to the lactonic alkaloids by oxidative coupling. 

Fuji K, Yamada T, Fujita E, Murata H 1978 Lythraceous alkaloids. X. Alkaloids of Lagerstroemia subcostata and L. fauriei A contribution to the chemotaxonomy. Chem Pharm Bull 26 2515-2521... 

The Blechert group also applied the tandem RRM process with CM (RCM-ROM-RCM sequence) to the synthesis of (—)-lasubine 11 (141, Scheme 24.36), an alkaloid extracted from the leaves of Lagerstroemia subcostata Koehne. ° This strategy requires a careful choice of substrates and catalysts to avoid the CM reaction before the RRM reaction takes place. Therefore, cyclopentenone 138 was chosen as a starting material from the outcome of their study. In the presence of [Ru]-II (5 mol%), the treatment... 

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