- Total synthesis of (-)-dihydrocorynantheol using bicyclo[3.2.1]octenone chiral building block
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The diastereocontrolled synthesis of (-)-dihydrocorynantheol from a bicyclo[3.2.l]octane chiral building block has been achieved by employing a tandem retro-aldol-Pictet-Spengler reaction-C-3 epimerization sequence as the key step.
- Tosaka, Ayako,Ito, Shinichiro,Miyazawa, Norio,Shibuya, Masatoshi,Ogasawara, Kunio,Iwabuchi, Yoshiharu
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- A Chiral Pentenolide-Based Unified Strategy toward Dihydrocorynantheal, Dihydrocorynantheol, Protoemetine, Protoemetinol, and Yohimbane
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An organocatalytic cross-aldol reaction of formaldehyde (formalin) with alkyl aldehydes, followed by the Z-selective Horner-Wadsworth-Emmons (HWE) reaction and immediate lactonization, afforded γ-alkylated pentenolides in good overall yields and excellent
- Xie, Changmin,Luo, Jisheng,Zhang, Yan,Zhu, Lili,Hong, Ran
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- A stereodivergent strategy for the preparation of corynantheine and ipecac alkaloids, their epimers, and analogues: Efficient total synthesis of (-)-dihydrocorynantheol, (-)-corynantheol, (-)-protoemetinol, (-)-corynantheal, (-)-protoemetine, and related
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Here we present a general and common catalytic asymmetric strategy for the total and formal synthesis of a broad number of optically active natural products from the corynantheine and ipecac alkaloid families, for example, indolo[2,3-a]- and benzo[a]quino
- Zhang, Wei,Bah, Juho,Wohlfarth, Andreas,Franzén, Johan
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- Enantioselective synthesis of indoloquinolizidines via asymmetric catalytic hydrogenation/lactamization of imino diesters
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We have developed a highly efficient cascade sequence for asymmetric synthesis of indoloquinolizidines with absolute control of cis-H2/H12b relative geometry in good to excellent yields and excellent enantioselectivities. This cascade was triggered by the Ru(II)-TsDPEN-catalyzed asymmetric transfer hydrogenation of imino diesters, with subsequent spontaneous lactamization with discrimination between the two diastereotopic 2-alkoxy-2-oxoethyl groups. The synthetic utility of this strategy was demonstrated by the asymmetric preparation of dihydrocorynantheol, geissoschizol, and isogeissoschizol.
- Liu, Yong,Wang, Qun,Zhang, Ying,Huang, Jianbiao,Nie, Linlin,Chen, Jie,Cao, Weiguo,Wu, Xiaoyu
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- Stereoselective total synthesis of dihydrocorynantheol.
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[reaction: see text] A stereoselective synthesis of the indole alkaloid dihydrocorynantheol (1) from indole-3-acetic acid has been achieved by a sequence involving 9 as a key intermediate. The synthesis of the unsaturated lactam ring in 9 highlights a series of catalytic organometallic reactions featuring two ring-closing metatheses and a zirconocene-catalyzed carbomagnesation. Since no protecting groups were used, the present synthesis of 1 is exceedingly concise, consisting of only eight distinct operations.
- Deiters, Alexander,Martin, Stephen F
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- Quinolizidines. XXXII. A Chiral Synthesis of 3,4,5,6-Tetradehydro-17-hydroxycorynanium, the Zwitterionic Structure Assigned to an Alkaloid from Aspidosperma marcgravianum
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The total synthesis of 3,4,5,6-tetradehydro-17-hydroxycorynanium , the zwitterionic structure assigned to an alkaloid from Aspidosperma marcgravianum, has been accomplished for the first time via a "lactim ether route".The route started with initial condensation between the lactim ether and 3-chloroacetylindole and proceeded through the lactam ester , lactam alcohol , acetoxylactam , quaternary iminium salt , and 3,4,5,6-tetradehydro-17-hydroxycorynanium perchlorate .The 1H NMR spectral data and the sign of specific rotation for the synthetic (+)-4 were in disagreement with those reported for a natural sample, leaving the chemistry of this A. marcgravianum alkaloid incomplete.
- Fujii, Tozo,Ohba, Masashi,Ohashi, Takako
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- Access to electron-rich arene-fused hexahydroquinolizinones through a gold-catalysis-initiated cascade process
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Golden Cascade: With a tethered, electron-rich arene as the internal nucleophile, a gold-catalyzed amide cyclization to an alkyne initiates a cascade process that ends with a Ferrier rearrangement. Electron-rich arene-bearing hexahydroquinolizin-2-ones are formed in good yields and can be converted into indole alkaloids in only a few steps. Copyright
- Liu, Lianzhu,Zhang, Liming
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supporting information; experimental part
p. 7301 - 7304
(2012/09/08)
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- Concise total synthesis of dihydrocorynanthenol, protoemetinol, protoemetine, 3-epi-protoemetinol and emetine
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A concise asymmetric assembly of secologanine tryptamine and dopamine alkaloids by means of a one-pot three-component cascade reaction methodology is disclosed. This is demonstrated by the expeditious total syntheses of (-)-dihydrocorynanthenol, (-)-protoemetinol, (-)-protoemetine, (-)-3-epi-protoemetinol, and emetine (3-6 steps). The biomimetic synthetic strategy involved the following key steps: (i) One-pot three-component highly enantioselective catalytic Michael/Pictet-Spengler/lactamization cascade reactions; (ii) One-pot tandem Swern oxidation/Wittig sequences; (iii) One-pot tandem hydrogenation sequences. Copyright
- Lin, Shuangzheng,Deiana, Luca,Tseggai, Abrehet,Cordova, Armando
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p. 398 - 408
(2012/02/16)
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- Organocatalytic approach for the syntheses of corynantheidol, dihydrocorynantheol, protoemetinol, protoemetine, and mitragynine
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O-Trimethylsilyl (TMS)-protected diphenylprolinol-catalyzed Michael addition of a functionalized alkylidene malonate and n-butanal affords an aldehyde. This adduct can serve as the common intermediate for the assembly of secologanin tryptamine and dopamin
- Sun, Xuefeng,Ma, Dawei
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p. 2158 - 2165
(2011/10/18)
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- Convenient synthesis of the key intermediate for dihydrocorynantheol and protoemetinol from the monoacetate of 4-cyclopentene-1,3-diol
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We invented an efficient method to obtain the key δ-lactone possessing the (CH2)2OTBDPS and Et groups at C3 and C4, respectively, starting with the acetate of 4-cyclopentene-1,3-diol, which was subjected to Pd-catalyzed allylation with malonate anion to attach the (CH 2)2OTBDPS group. The Et group was then installed by 1,4-addition to the derived enone. Finally, the resulting enol TMS ether was oxidized to afford the lactone. Furthermore, the lactone was converted to dihydrocorynantheol and protoemetinol, both of which are typical examples of indoloquinolizidine and benzo[α]quinolizine alkaloids. The Japan Institute of Heterocyclic Chemistry.
- Kobayashi, Yuichi,Yagi, Kaori,Kaneko, Yuki
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p. 1541 - 1548
(2011/05/05)
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- A divergent strategy for the synthesis of secologanin derived natural products
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The syntheses of d,l-geissoschizol, d,l-corynantheidol, d,l-dihydrocorynantheol, d,l-protoemetinol, and d,l-3-epi-protoemetinol have been accomplished from a single synthetic intermediate.
- English, Brandon J.,Williams, Robert M.
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supporting information; experimental part
p. 7869 - 7876
(2011/02/21)
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- General strategy for the syntheses of corynanthe, tacaman, and oxindole alkaloids
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We report herein the total synthesis of the corynanthe alkaloid dihydrocorynantheol and the formal syntheses of the indole alkaloids tacamonine, rhynchophylline, and hirsutine. The strategies for assembling the corynanthe and tacaman skeletal frameworks comprised of both the classical ABD → ABCD and ABC → ABCD approaches wherein the variously substituted piperidinone D-rings were formed via ring-closing metathesis (RCM) followed by a 1,4-addition to introduce the requisite side chain at C(15). Since 1,4-additions to α,β-unsaturated lactams represent an underdeveloped field, we conducted a series of studies with two unsaturated lactams employing organocuprates and metal enolates as the nucleophiles. These studies revealed that organocuprates derived from Grignard reagents and either stoichiometric amounts of CuCN or catalytic amounts of CuBr·DMS complex are excellent nucleophiles for such additions; TMSC1 was a crucial additive for optimizing these reactions. The anion derived from ethyl 1,3-dithiolane-2-carboxylate was also an excellent nucleophile in these 1,4-additions, although the stereochemistry of such 1,4-additions to carboline-derived, unsaturated lactams was sensitive to substitution on the indole nitrogen atom. The ABD → ABCD approach to these alkaloids featured a novel one-pot sequence of an RCM reaction and a zirconocene-catalyzed carbomagnesation followed by a second RCM to generate the D-ring.
- Deiters, Alexander,Pettersson, Martin,Martin, Stephen F.
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p. 6547 - 6561
(2007/10/03)
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- Synthetic studies on indole alkaloids. VI synthesis of tetrahydroakuammicine and dihydrocorynantheol via 2-(3-indolyl)-4-piperidones
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The synthesis of dihydrocorynantheol (5) and of the pentacyclic Strychnos alkaloid tetrahydroakuammicine (4) is reported from 5-ethyl-N-hydroxyethyl-2-(1-phenylsulfonyl-3-indolyl)-4-piperidineacet ates (1) by means of a K(t)OBu/BF3.Et2/su
- Diez,Vila,Sinibaldi,Troin,Rubiralta
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p. 733 - 736
(2007/10/02)
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- SYNTHESES OF (+/-)-Z-GEISSOSCHIZOL, (+/-)-3-EPI-Z-GEISSOSCHIZOL, (+/-)-CORYNANTHEIDOL, (+/-)-DIHYDROCORYNANTHEOL, (+/-)-3-EPI-DIHYDROCORYNANTHEOL AND THE CORRESPONDING CORYNAN-17-OIC ACID METHYL ESTERS
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The utility of the Claisen rearrangement using carefully separated, diastereoisomeric allylic alcohols (1a) and (1b) in the preparation of (+/-)-Z-geissoschizol (4a), (+/-)-3-epi-Z-geissoschizol (4b), (+/-)-corynantheidol (7a), (+/-)-dihydrocorynantheol (8a), (+/-)-3-epi-dihydrocorynantheol (8b) and the corresponding corynan-17-oic acid methyl esters (3a, 3b, 5a, 6a and 6b) is shown.Special attention is paid to the stereochemical outcome of catalytic (PtO2) hydrogenation of the C(20) Z-ethylidene side chain.
- Lounasmaa, Mauri,Jokela, Reija,Tirkkonen, Birgit,Miettinen, Jari,Halonen, Minna
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p. 321 - 339
(2007/10/02)
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- New approaches to Corynanthe alkaloids involving the conjugate addition of dialkyl malonates to unsaturated thiolactams: Synthesis of (±)-3-epi-dihydrocorynantheol
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Addition of dimethyl malonate to thiolactam 8 led to a mixture of Michael adducts 9 and 10 (6:1, respectively). Compound 9 has been converted in 4 steps into (±)-3-epi-dihydrocorynantheol 16.
- Gomez-Pardo,Desmaele,D'Angelo
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p. 6633 - 6636
(2007/10/02)
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- Asymmetric Synthesis of the Corynantheine Alkaloids via an Intramolecular Blaise Reaction. (-)-Corynantheidol and (-)-Dihydrocorynantheol
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An asymmetric total synthesis of the corynantheine family of alkaloids has been accomplished, leading to corynantheidol (1a) and dihydrocorynantheol (1b).Formal synthesis to corynantheidine and dihydrocorynantheine are also shown.The key to this asymmetric route is the use of (1) chiral β-carboline formamidines, which allow high degrees of diastereoselection at C-3 with chloroacetonitrile, and (2) a new version of the Blaise reaction using Zn-Ag couple and ultrasonic radiation.These two synthetic techniques combine to allow an efficient entry into the title compounds.The overall yield of 1a was 16.4percent in seven steps from starting carboline 5.
- Beard, Richard L.,Meyers, A. I.
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p. 2091 - 2096
(2007/10/02)
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- QUINOLIZIDINES. XXIX. PREPARATION OF (-)-DIHYDROCORYNANTHEOL
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An alternative, total synthesis of the indoloquinolizidine alkaloid (-)-dihydrocorynantheol , adaptable to that on a gram scale preparation, has been achieved via a "lactim ether route".The route started with an initial condensation between the lactim ether and 3-(chloroacetyl)indole and proceeded through the lactam ketone , oxazolium salt (6), N-substituted lactam , quaternary iminium salt (9), and tetracyclic ester .
- Ohba, Masashi,Ohashi, Takako,Fujii, Tozo
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p. 319 - 328
(2007/10/02)
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- Homochiral Syntheses of (-)-Dihydrocorynantheol
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A Corynanthe-type indole alkaloid, (-)-dihydrocorynantheol (7), was enantioselectively synthesized from (+)-(4S,5R)-4-(2-benzyloxyethyl)-5-ethyl-3,4,5,6-tetrahydro-2-pyrone (3), derived from ethylmalonic acid.The synthetic compound (7) was identical in al
- Ihara, Masataka,Taniguchi, Nobuaki,Yasui, Ken,Fukumoto, Keiichiro
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p. 2771 - 2773
(2007/10/02)
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- SHORT SYNTHESIS OF (+/-)-CORYNANTHEIDOL AND (+/-)-3-EPICORYNANTHEIDOL
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A short synthesis for (+/-)-corynantheidol and (+/-)-3-epicorynantheidol is described.
- Lounasmaa, Mauri,Jokela, Reija
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p. 1351 - 1358
(2007/10/02)
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- A Stereoselective Total Synthesis of (+/-)-Dihydrocorynantheol via Radical Cyclisation
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Stereoselective total synthesis of (+/-)-dihydrocorynantheol (1) has been accomplished via radical cyclisation of a bromoacetal (9) of a homoallylic alcohol.
- Ihara, Masataka,Taniguchi, Nobuaki,Fukumoto, Keiichiro,Kametani, Tetsuji
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p. 1438 - 1439
(2007/10/02)
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- An Enantioselective Total Synthesis of (-)-Dihydrocorynantheol
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The total synthesis of (-)-dihydrocorynantheol (3) has been achieved using a potentially useful chiral synthon, thioketal carboxylic acid (8), derived from (R)-1,2-isopropylideneglyceraldehyde (4) in 7 steps.Keywords - enantioselective total synthesis; (-)-dihydrocorynantheol; (R)-1,2-isopropylideneglyceraldehyde; chiral synthon; Corynanthe-type indole alkaloid
- Suzuki, Toshio,Sato, Etsuko,Unno, Katsuo,Kametani, Tetsuji
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p. 1584 - 1588
(2007/10/02)
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- THE TOTAL SYNTHESIS OF (-)-DIHYDROCORYNANTHEOL
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The total synthesis of (-)-dihydrocorynantheol (4) has been achieved using a potentially useful chiral synthon, thioketal carboxylic acid (2).
- Suzuki, Toshio,Sato, Etsuko,Unno, Katsuo
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p. 835 - 838
(2007/10/02)
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- A Specific and Efficient Synthesis of (+/-)-Dihydrocorynantheol
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A specific and efficient synthesis of (+/-)-dihydrocorynantheol (1) is reported.Starting with the easily accessible imine (3), ring D was built via stereoselective reaction with the lactone (4a), thus providing the complete carbon skeleton of (1); subsequ
- Danieli, Bruno,Lesma, Giordano,Palmisano, Giovanni,Tollari, Stefano
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p. 1237 - 1240
(2007/10/02)
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- Stereoselective Total Synthesis of (+/-)-Hirsutine and Related Corynanthe Alkaloids
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In a completely stereoselective sequence, an analogue of dihydrosecologanin aglucone has been synthesised via a novel cyclopentenedione dimer and converted into tetracyclic indole alkaloids.
- Brown, Richard T.,Jones, Martin F.,Wingfield, Mark
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p. 847 - 848
(2007/10/02)
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- GUETTARDINE, A POSSIBLE BIOGENETIC INTERMEDIATE IN THE FORMATION OF CORYNANTHE-CINCHONA ALKALOIDS
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The structure of guettardine 1, an indole alkaloid isolated from the bark of Guettarda heterosepala (Rubiaceae), was determined from an analysis of its MS, 1H and 13C NMR spectral data,and by a chemical correlation with dihydrocorynantheol 7.Guettardine 1 can be considered to be an intermediate between the Corynanthe and the cinchonamine groups of alkaloids which are precursors of quinine and its derivatives.
- Brillanceau, M. H.,Kan-Fan, C.,Kan, S. K.,Husson, H.-P.
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p. 2767 - 2770
(2007/10/02)
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- A NEW SYNTHETIC ROUTE TO THE CORYNANTHE TYPE INDOLE ALKALOIDS USING (+/-)-NORCAMPHOR
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Conversion of (+/-)-norcamphor (5) into a number of the corynanthe alkaloids in racemic forms has been achieved.The conversion allows a formation the 18,19-saturated alkaloids with all four possible configurations and Δ18,19-unsaturated alkaloi
- Takano, Seiichi,Shibuya, Kimiyuki,Takahashi, Mikoto,Hatakeyama, Susumi,Ogasawara, Kunio
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p. 1125 - 1131
(2007/10/02)
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- STUDIES ON THE SYNTHESES OF HETEROCYCLIC AND NATURAL COMPOUNDS. PART 949. A TOTAL SYNTHESIS OF (+/-)-CORYNANTHEIDOL
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A facile synthesis of (+/-)-corynantheidol (17) has been achieved by the application of enamine annelation using 3,4-dihydro-1-methyl-β-carboline (5) and dimethyl 3-methoxyallylidenemalonate (6).Stereochemical assignment for catalytic hydrogenation products of the corresponding enamides has also been investigated.
- Kametani, Tetsuji,Kanaya, Naoaki,Honda, Toshio
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p. 1937 - 1946
(2007/10/02)
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- A Stereoselective Synthesis of Corynantheine-type Alkaloids via Enamine Annulation. Total Synthesis of (+/-)-Dihydrocorynantheol and Formal Total Synthesis of (+/-)-Corynantheine and (+/-)-Ajmalicine
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Enamine annulation between 3,4-dihydro-1-methyl-β-carboline (4) and dimethyl 3-methoxyallylidenemalonate (5) yielded 2-(2,2-dimethoxyethyl)-2,3,4,6,7,12-hexahydro-3-methoxycarbonyl-4-oxoindoloquinolizine (6), which was transformed into (+/-)-dihydrocorynantheol (1). (+/-)-Corynantheal (19), which is convertible into (+/-)-corynantheine (2) and (+/-)-ajmalicine (3), was stereoselectively synthesised from (6) via epimerisations at the angular position using Adams catalyst.
- Kametani, Tetsuji,Kanaya, Naoaki,Hino, Hiroaki,Huang, Shyh-Pyng,Ihara, Masataka
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p. 3168 - 3175
(2007/10/02)
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- STEREOSELECTIVE SYNTHESIS OF (+/-)-DIHYDROCORYNANTHEOL VIA ENAMINE ANNELATION
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A facile stereoselective synthesis of (+/-)-dihydrocorynantheol (8) was achieved via the key step of enamine annelation using 3,4-dihydro-1-methyl -β-carboline (1) and dimethyl 3-methoxyallidenemalonate (2).
- Kametani, Tetsuji,Kanaya, Naoaki,Hino, Hiroaki,Huang, Shyh-Pyng,Ihara, Masataka
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p. 1771 - 1774
(2007/10/02)
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