Biomimetic Synthesis of Nauclea Indole Alkaloids, Naucleidinal, and 3-epi-Naucleidinal, by Stereoselective Rearrangement of Strictsamide and the Vincoside Lactam Aglycones.

Recent progress in the chemistry of the monoterpenoid indole alkaloids

“…A biomimetic conversion of strictosamide 11a into naucleidinal 12a, the alkaloid of Nauclea latifolia and N. officinalis, has been achieved by removal of the glucose unit, and heating the resulting strictosamide aglycone in aqueous pyridine (Scheme 3). 15 The stereochemistry of the product was established by the observation of a NOE between H-15 and H-19, and by the large J 19,20 and J 15,20 coupling constants, which argues for an axial arrangement of hydrogen atoms at C-15, C-19 and C-20; further, the CD spectrum reveals that naucleidinal contains -hydrogen at C-3. Similarly, vincosamide 11b, the 3 -H epimer of 11a, gives 3-epinaucleidinal 12b, which has so far not been found in nature.…”

“…The 15 N chemical shifts and long range 1 H- 15 N coupling pathways for strychnine, brucine and holstiine have been established, 56 and complete assignments of all the 13 C and proton chemical shifts in both amide rotamers of strychnobrasiline have been made. 57 Bosch and his co-workers have reported the first enantioselective synthesis of ( )-tubifoline, 58 together with syntheses of ( )-norfluorocurarine, ( )-akuammicine, 59 ( )tubifolidine, ( )-19,20-dihydroakuammicine, and a second synthesis of ( )-akuammicine.…”

“…Tenuisine B 266 is 11,11 -dimethoxytenuisine A, and tenuisine C 267 is 3,3dioxotenuisine A. 103 The long-range 1 H, 15 N couplings and 15 N chemical shifts have been assigned for navelbine (5 -noranhydrovinblastine) by application of gradient-enhanced HMQC for the observation of long-range heteronuclear couplings at natural abundance. 104 Kuehne and Bandarage 105 have improved the enantioselectivity of an earlier synthesis 46 of vinblastine by making use of a chiral auxiliary derived from ferrocene for the construction of the vital intermediate 270.…”

Chemistry of Indole Alkaloids Related to the Corynanthe-Type from Uncaria, Nauclea and Mitragyna Plants

“…Further, recent pharmacological studies of oxindole alkaloids, which are the constituents of this herbal medicine, have suggested that pteropodine (59) and isopteropodine (60), which are heteroyohimbine-type oxindole alkaloids, act as positive modulators of muscarinic M 1 and 5-HT 2 receptors [37], and rhynchophylline (6) and isorhynchophylline (8), which are Corynanthe-type oxindole alkaloids, act as noncompetitive antagonists of the N-methyl-D-aspartate (NMDA) receptor in Xenopus oocytes [38]. Peruvian Uña de Gato used in our study was the powdered stem of U. tomentosa.…”

“…Based on biogenetic considerations, a Nauclea alkaloid, naucleidinal ( 87), and its 3-epimer (88) the aglycons of strictosamide and vincoside lactam, and their absolute stereochemistry was confirmed [60].…”