Alkaloid studies. LIX. Structure and absolute configuration of vallesamidine

Abstract

equivalent* and uI = 0.5 for fluorine, we calculate that the inductive effect alone of a 9 fluorine would result in a rate increase of lo5; hence, the ?r-conjugation effect actually results in a millionfold rate decrease.By contrast, two a fluorines increase the LiCHAcatalyzed exchange of toluene by a factor of >104.'j (6) D. J. Cram, "Fundamentals of Carbanion Chemistry," Academic Press Inc., New York, N. Y . , 1965, p 59, reports that all four hydrogens of m-methylbenzal fluoride undergo hydrogen-deuterium exchange at comparable rates with potassium t-butoxide in t-butyl alcohol-d. This corresponds to a far slower relative rate for the difluoromethyl hydrogen than we have found, but this apparent discrepancy may very well be due to extensive internal return in the t-butyl alcohol system.(7) On leave from the Institute

Alkaloids from Roots ofStrempeliopsis strempelioides- Structures of Strempeliopine and Strempeliopidine

“…Besides the known alkaloids (+)-pleiocarpamine (7,8), (-)aspidospermine (9-12), (+)-eburnamonine (13)(14)(15), (+ )-tubotaiwine (16), (+)-haplocidine (17,18), (-)-vallesamidine (19,20), (+)-tubotaiwine N-oxide (21), the hitherto unknown alkaloids strempeliopine (la) and bisindole compounds strempeliopidine (2) and a base of the formula C38HH4 were isolated. Haplocidine was correlated to fannine in a two step reaction (6).…”

“…Strempeliopidine 2 Compound CHN4: m.p. 158-171° C; [aJ° +210° (chloroform); UV: 234(4.13)and294(3.66);LR: 3350,2880,1620,1490, 1310and750 cm; MS (m/z, relative abundance): 558 (M, C38HN4, 100%), 557 (27), 530(5), 529(7), 488 (25), 459(3), 309(3), 308(3), 295(5), 294(7), 293 (4), 279(14), 252 (19), 249 (8), 208(7), 180 (5), 167 (12), 156(10), 124(17), 111(7), 109(13),97 (20),85 (27),83(22),81 (21)and7l (50).…”

Asymmetric total synthesis of (+)-.DELTA.9(12)-capnellene

“…The residue was dissolved in ether and washed with water and brine. Chromatography (Et20/hexanes 1:2) gave 124 mg (78%) of (+)-23: [«]% +58.6°( c, 1.44, CHC13); IR 3074,1713,1672 cm'1; NMR 7.42 (d, J = 5.6, 1 ), 6.04 (d, J = 5.6,1 ), 3.98-3.90 (m, 4 H), 2.32, 2.12 (AB, Jab = 18.7, 2 ), 1.64-1.55 (m, 4 ), 1.29 (s, 3 ), 1.22 (S)-4-(3,3-Ethylenedioxybutyl)-4-methyl-2-cyclopenten-1-one (S-(-)-23). In a fashion similar to that described for (fi)-(+)-23, the bicyclic lactam (+)-19 was subjected to the same series of reactions (ozonolysis, ketalization, reduction, and hydrolysis).…”

“…The aspidospermine skeleton can be generated by oxidative cyclization of quebrachamine (6).13,14 Vallesamidine differs from aspidospermine in that C-19 is attached to the indoline ring at C-2 rather than at C-12, suggesting that the biosynthesis of Aspidosperma alkaloids involves quebrachamine-type intermediates and that vallesamidine may be regarded as the product of an "abnormal" cyclization, generating the same stereochemistry at carbons 2, 12, and 19 as the "normal" (Aspidosperma) cyclizations.6 Et x>…”

Recent developments in syntheses of the post-secodine indole alkaloids. Part III: Rearranged alkaloid types

“…The following reduction/reductive methylation using NaBH 3 CN as the reducing agent gave lactam 1156 (90%) which, upon final heating with LiAlH 4 to reflux, afforded racemic (±)-vallesamidine (1144) in 92% yield. (-)-Vallesamidine (1144) was isolated from Vallesia dichotoma 65 and Strempeliopsis strempelioides 66 .…”