Grandisin

The NMR spectra of indolizidine derivatives have already been described accurately <1984CHEC(4)443 1996CHEC-II(8)237> more recently, the extensive use of mono- and bidimensional H and 13C NMR spectra allowed the structural assignment of natural compounds such as grandisine A possessing an indolizidine nucleus (Figure 3) <2005JOC1889>. 

Grandisine Active against mouse leukemia L1210 cells — 145... 

Grandisine-I 1,5-diOH, 3,6-diOMe, 10-Me Citrus grandis [17], C. maxima [40]... 

Figure 21 Alkaloids isolated from Elaeocarpus grandis isoelaeocarpiline (851) +)-grandisine A (852) grandisine B (853) (—)-grandisine C (854) grandisine D (855) grandisine E (856) (-)-grandisine F (857) grandisine G (858) mearsine (859).

Whether grandisines B, F, and G are true alkaloids or artifacts of the isolation procedure is moot. Carroll confirmed in a personal commimication... 

Scheme 107 Possible biogenesis of the grandisines." (a) Condensation (b) aldol reaction (c) retro-aldol reaction (d) reduction (e) cyclization, dehydration (f) reduction (g) amination (h) cyclization and dehydration (imine formation) (i) methanolysis (j) enolization and cyclization (k) hydration.

Tamura and coworkers have reported a fairly general route to several of the grandisines and analogs in which the chiral imide (—)-877, itself prepared by a known route from L-mahc acid, ° served as the precursor (Scheme 109). Regioselective reduction, ethanolysis, and cross-metathesis... 

Another short synthesis of (+)-grandisine D (855), by Lindsley and coworkers, took advantage of the inherent chirahty of (5)-teri-butyl sulfin-amide to control the absolute stereochemistry of the target (Scheme 112). The diol 902 was converted in three steps into the (S)-N-sulfinyl... 

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