Polyneuridine aldehyde

At the outset we would like to emphasize the generally easy interconversion between ajmaline and sarpagine derivatives, schematically presented here for the not yet naturally found 1,2-didehydroquebrachidine (142) and polyneuridine aldehyde (143) (Scheme 9). 

Polyneuridine aldehyde esterase Rauvolfia serpentina Rauvolfia serpentina... 

First enantiospecific total syntheses of biogenetic intermediates on the way to sarpagine (5), such as polyneuridine aldehyde (46) or 16-epi-vellosimine (49), have been reported recently by Cook and coworkers. For most recent publications see Refs 43,44. 

Polyneuridine aldehyde esterase catalyzes the conversion of polyneuridine aldehyde (48) to 16- i-veUosimine (49) through the intermediate polyneuridine aldehydoacid (64) The intermediate 64 could not be isolated up to now. Because of its high instability, probably it spontaneously decar-boxylates to the enzyme product 49, see Figure 14. 

Figure 14 Catalytic function of polyneuridine aldehyde esterase (PNAE), delivering the pathway intermediate 49 through the unstable alkaloid polyneuridine aldehydoacid (64). Taken from Ref. 106.

PNAE), converts the intermediate polyneuridine aldehyde (11) into 16-epi-veUosimine (10). ... 

---