Alkaloids from tonduzia pittieri

A General Strategy for the Synthesis of Vincamajine-Related Indole Alkaloids: Stereocontrolled Total Synthesis of (+)-Dehydrovoachalotine, (−)-Vincamajinine, and (−)-11-Methoxy-17-epivincamajine as Well as the Related Quebrachidine Diol, Vincamajine Diol, and Vincarinol1

“…The aldehydic group in 63 was converted into the methyl ester 64 in 91% yield by the elegant procedure of Yamamoto et al The C(17) ketone which remained was stereoselectively reduced from the top face to furnish the synthetic (−)-11-methoxy-17-epivincamajine ( 9 ) in 93% yield with NaBH 4 in EtOH. The spectroscopic properties and optical rotation [[α] 26 D −10.5 (lit 9b. [α] 26 D −12.0)] of synthetic (−)- 9 were in excellent agreement with those of natural (−)-11-methoxy-17-epivincamajine ( 9 ).…”

“…The mixture which resulted was diluted with CH 2 Cl 2 (5 mL), washed with brine (2 × 10 mL), dried (Na 2 SO 4 ), and filtered and the solvent removed under reduced pressure. The residue that resulted was purified by preparative TLC on silica gel (CHCl 3 /MeOH = 9:1) to provide 9 as a pale yellow foam (3.5 mg, 93%): [α] D = −10.5 ( c 0.15, CHCl 3 ) [lit 9b. [α] D = −12 ( c 0.5, CHCl 3 )]; FTIR 3300, 2918, 1720, 1612, 1461, 787 cm -1 ; 1 H NMR (300 MHz, CDCl 3 ) δ 1.52 (dd, J = 14.1, 10.0 Hz, 1 H), 1.62 (d, J = 6.8 Hz, 3 H), 1.73 (m, 1 H), 2.27 (dd, J = 12.1, 4.5 Hz, 1 H), 2.68 (s, 3 H), 2.99 (dd, J = 13.2, 5.2 Hz, 1 H), 3.41 (d, J = 4.7 Hz, 1 H), 3.44 (d, J = 4.6 Hz, 1 H), 3.47 (m, 2 H), 3.48 (d, J = 4.8 Hz, 1 H), 3.60 (m, 1 H), 3.72 (s, 3 H), 3.82 (s, 3 H), 4.00 (s, 1 H), 5.29 (q, J = 6.8 Hz, 1 H), 6.33 (d, J = 2.2 Hz, 1 H), 6.40 (dd, J = 8.1, 2.2 Hz, 1 H), 6.97 (d, J = 8.0 Hz, 1 H); 13 C NMR (75.5 MHz, CDCl 3 ) δ 12.9, 22.7, 29.6, 34.9, 35.8, 52.1, 53.3, 53.7, 54.1, 55.4, 56.0, 61.7, 76.5, 85.9, 97.4, 104.5, 116.4, 122.0, 122.8, 136.6, 156.4, 160.7, 175.0; EIMS ( m / e , relative intensity) 396 (M + , 100), 365 (17), 222 (87), 190 (83), 187 (64), 174 (29).…”

“…(+)-Alstomacroline ( 1 ), a bisindole alkaloid, was isolated from the root bark of A. macrophylla collected in Thailand and exhibited potent activity against drug-resistant strains of malaria parasites (IC 50 of 1.12 μM against the K1 strain of Plasmodium falciparum ). , A partial synthesis of 1 was reported by Le Quesne et al via a biomimetic coupling process by condensation of the two components, (+)-quebrachidine ( 3 ) and macroline ( 10 ) (Figure ). The related bisindole alkaloid (−)-11-methoxy-10-(11‘-vincorinyl)-17-epivincamajine ( 2 ) was isolated in 1992 from the leaves of Tonduzia pettieri ( Alstonia pettieri ),9a accompanied by the monomeric base (−)-11-methoxy-17-epivincamajine ( 9 ) . The latter two alkaloids have not been evaluated for antimalarial activity to date.…”

“…(+)-Vincarine ( 8 ), an N a -H analogue of (−)-vincamajinine, was isolated from Vinca erecta , Vinca herbacea , and Vinca major . The constitution and relative configuration of these indole alkaloids were determined on the basis of NMR studies and chemical correlation or confirmed by chemical conversion and spectral data. − These indole alkaloids typically possess a unique rigid, caged hexacyclic carbon skeleton which contains seven stereogenic centers (carbons 2, 3, 5, 7, 15, 16, and 17) as well as the key olefinic bond at C(19)−C(20) in the E -configuration. However, the configuration of the C(17)-hydroxyl group in 3 − 6 [17( S )] is different from that in 7 − 9 [17( R )].…”

A New Structural Class of Bisindole Alkaloids from the Seeds of Catharanthus roseus: Vingramine and Methylvingramine

“…It would appear that in the seeds of C. roseus , in contrast to other parts of the plant, monomer alkaloids undergo oxidative coupling into 11,10‘-bisindole at an early step of biogenesis before more complex rearrangements take place. , The biphenyl bisindoles of the other Apocynaceae, unknown in the Catharanthus species, were found in various biogenetic states, such as 10,11‘-dimethoxyvincamajinyl-cathafolines before skeleton rearrangement; pelankine, cabufiline, desoxycabufiline, and (11-methoxyvancamajinyl)-vincorines23a after half-rearrangement to vincorine; peceyline and peceylanine 21 after two-portion skeleton rearrangements into the vincorine−vincovine 23b type of alkaloids.…”