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1.
《Tetrahedron: Asymmetry》2007,18(18):2211-2217
(1R,2S,3R,5S,7aR)-1,2-Dihydroxy-3-hydroxymethyl-5-methylpyrrolizidine 10 [(+)-5-epihyacinthacine A5] and (1R,2S,3R,5S,7aS)-1,2-dihydroxy-3-hydroxymethyl-5-methylpyrrolizidine 17 [ent-5-epihyacinthacine A4] have been synthesized by either Horner–Wadsworth–Emmons (HWE) or Wittig methodology using aldehydes 6 and 13, prepared from (2R,3S,4R,5R)-3,4-dibenzyloxy-N-benzyloxycarbonyl-2′-O-tert-butyldiphenylsilyl-2,5-bis(hydroxymethyl)pyrrolidine 5 (partially protected DALDP) and (2R,3S,4R,5S)-3,4-dibenzyloxy-N-benzyloxycarbonyl-2,5-bis(hydroxymethyl)-2′-O-pivaloylpyrrolidine 12 (partially protected DGADP), respectively, and the appropriated ylide, followed by cyclization through an internal reductive amination process of the corresponding intermediate pyrrolidinic ketones 7 and 14 and subsequent deprotection. 相似文献
2.
Narihito Ogawa 《Tetrahedron letters》2008,49(50):7124-7127
The TES ether of 2-((1R,2S,3R)-3-hydroxy-2-((Z)-pent-2-enyl)cyclopentyl)acetic acid (5, equal to the reduction product of epi-jasmonic acid) derived from (1R,4S)-4-hydroxycyclopent-2-enyl acetate (19) in 13 steps was activated by using isobutyl chloroformate and was subjected to condensation with isoleucine at room temperature for 48 h. The product was desilylated and oxidized to the isoleucine conjugate of epi-jasmonic acid in 68% yield over three steps. Similarly, allo-isoleucine conjugate of epi-jasmonic acid and three isoleucine conjugates of ent-epi-jasmonic acid, jasmonic acid, and ent-jasmonic acid were synthesized. 相似文献
3.
《Tetrahedron: Asymmetry》2004,15(9):1465-1469
(1R,2R,3S,5R,7aR)-1,2-Dihydroxy-3-hydroxymethyl-5-methylpyrrolizidine [(+)-3-epi-hyacinthacine A3] 1 and (1R,2R,3S,7aR)-1,2-dihydroxy-3-hydroxymethylpyrrolizidine [(+)-3-epi-hyacinthacine A2] 2 have been synthesized by Wittig's methodology using aldehyde 6, prepared from (2R,3R,4R,5S)-3,4-dibenzyloxy-N-benzyloxycarbonyl-2′-O-tert-butyldiphenylsilyl-2,5-bis(hydroxymethyl) pyrrolidine 3 (a partially protected DGDP), and the appropriated ylides, followed by cyclization through an internal reductive amination process of the resulting α,β-unsaturated ketone 7 and aldehyde 8, respectively, and total deprotection. 相似文献
4.
Herbert Cadosch Ulrich Vgeli Peter Rüedi Conrad Hans Eugster 《Helvetica chimica acta》1978,61(5):1511-1519
Structure and properties of 5-epi-flavoxanthin and 5-epi-chrysanthemaxanthin The absolute configurations of 5-epi-flavoxanthin ( 6 ) and 5-epi-chrysanthemaxanthin ( 7 ) prepared by acid catalysed rearrangement of semi-synthetic lutein epoxide 5 are shown to be (3S, 5S, 8R, 3′R, 6′R) and (3S, 5S, 8S, 3′R, 6′R), respectively. Contrary to published data [5] the relationship of the polyene chain and H3(18) on the dihydrofurane ring is cis for the pair of stereoisomers having a Δδ = δ (H? C(7)) ? δ (H? C(8)) = 0,22 ppm and 3J ≡ 0. These conclusions are in full accord with the chiroptical data. 相似文献
5.
Nermeen A. Eltahawy Amany K. Ibrahim Mohamed M. Radwan Mahmoud A. ElSohly Hashim A. Hassanean Safwat A. Ahmed 《Tetrahedron letters》2014
Chemical investigation of the Red Sea soft coral Sarcophyton auritum led to the isolation and structure elucidation of two new diterpene cembranoids; 2-epi-sarcophine (2) and (1R,2E,4S,6E,8R,11R,12R)-2,6-cembradiene-4,8,11,12-tetrol (4), as well as two known diterpene cembranoids, reported for the first time from this species, namely sarcophine (1) and (+)-7α,8β-dihydroxydeepoxysarcophine (3). Structure elucidation was achieved using spectroscopic techniques, including 1D and 2D NMR and HRMS. The isolated cembranoids were found to display high cytotoxicity against HepG2 (liver cancer cell line) and MCF-7 (breast cancer cell line). 相似文献
6.
A short, versatile, and enantioselective synthesis of 1-deoxy-8-epi-castanospermine (5), 1-deoxy-8-hydroxymethyl castanospermine (6), and (6S,7S,8R,8aR)-8-amino-octahydroindolizine-6,7-diol (7) is achieved from a common template 12. The key step utilized is PET provoked amine radical cyclization of 11 to 12 in excellent diastereoselectivity. The exocyclic double bond at C-8 of the template is functionalized to obtain 5-7 as exclusive diastereomers. 1-Deoxy-8-epi-castanospermine exhibited inhibition of α- and β-galactosidase and β-glucosidase. Compounds 6 and 7 were found to be weak inhibitors of β-glucosidase. 相似文献
7.
Isidoro Izquierdo María T. Plaza Juan A. Tamayo Miguel Rodríguez Alicia Martos 《Tetrahedron》2006,62(25):6006-6011
(1R,2S,3S,5R,7aR)-1,2-Dihydroxy-3-hydroxymethyl-5-methylpyrrolizidine[(−)-3-epihyacinthacine A5, 1a] and (1S,2R,3R,5S 7aS)-1,2-dihydroxy-3-hydroxymethylpyrrolizidine[(+)-3-epihyacinthacine A5, 1b] have been synthesized either by Wittig's or Horner-Wadsworth-Emmond's (HWE's) methodology using aldehydes 4 and 9, both prepared from (2S,3S,4R,5R)-3,4-dibenzyloxy-2′-O-tert-butyldiphenylsilyl-2,5-bis(hydroxymethyl)pyrrolidine (2, partially protected DADP), and the appropriate ylides, followed by cyclization through an internal reductive amination process of the resulting α,β-unsaturated ketones 5 and 10, respectively, and total deprotection. 相似文献
8.
《Tetrahedron: Asymmetry》2001,12(17):2481-2487
Two short and highly stereocontrolled syntheses for 7a-epi-hyacinthacine A2 (7-deoxyalexine) 3 and 5,7a-diepi-hyacinthacine A3 4 are, respectively, reported herein. An appropriately protected polyhydroxypyrrolidine, (2R,3R,4R,5S)-3,4-dibenzyloxy-N-benzyloxycarbonyl-2′-O-tert-butyldiphenylsilyl-2,5-bis(hydroxymethyl)pyrrolidine 5, readily available from d-fructose, was chosen as the chiral starting material. 相似文献
9.
Pedro Joseph-Nathan Suzana Guimarães Leitão Gilda Guimarães Leitão Fabio Luiz Paranhos Costa Natalia Martinez Angelina Hernández-Barragán 《Tetrahedron letters》2010,51(15):1963-1965
Reevaluation of 13C NMR data in combination with X-ray diffraction and VCD studies led us to reassign the structure of (−)-epi-presilphiperfolan-1-ol (1), isolated from Anemia tomentosavar.anthriscifolia, to (−)-9-epi-presilphiperfolan-1-ol (2) and to establish its absolute configuration as 1S,4S,7R,8R,9S. 相似文献
10.
Naturally occurring (1S,2R,3R,5R,7aR)-1,2-dihydroxy-3-hydroxymethyl-5-methylpyrrolizidine [(+)-hyacinthacine A6, 2] together with unnatural (1S,2R,3R,7aS)-1,2-dihydroxy-3-hydroxymethylpyrrolizidine [(+)-7a-epi-hyacinthacine A1, 3] and (1S,2R,3R,5S,7aS)-1,2-dihydroxy-3-hydroxymethyl-5-methylpyrrolizidine [(+)-5,7a-diepi-hyacinthacine A6, 4] have been synthesized from a DALDP derivative [5, (2R,3S,4R,5R)-3,4-dibenzyloxy-2′-O-tert-butyldiphenylsilyl-2,5-bis(hydroxymethyl)pyrrolidine], as the homochiral starting material. The synthetic process employed took advantages of Wittig methodology followed by internal lactamization, in the case of (+)-7a-epi-hyacinthacine A1 (3), and reductive amination for (+)-hyacinthacine A6 (2) and (+)-5,7a-diepi-hyacinthacine A6 (4). 相似文献
11.
An investigation was conducted to identify the structures and bioactive properties of five compounds isolated from the Halichondrida sponges Amorphinopsis foetida and Axinyssa aplysinoides. All compounds possessed the spiro-axane sesquiterpene core and all were substituted at C-2 with nitrogen containing functionality. The stereochemistry of one known compound has been revised to (2R,5R,10S)-2-formamido-6-axene (3). It exhibited mild selective solid tumor and mild antibacterial activity and was found from Axinyssa. A second known substance whose stereochemistry has also been revised, (2R,5R,10S)-2-isothiocyanato-6-axene (4) plus its undescribed diastereomer (5) were isolated from Amorphinopsis. Both sponges were the source of two new N-phenethyl-2-formamido-6-axene diastereomeric compounds 6 and 7. No solid tumor or antibacterial activity was found for 4-7. 相似文献
12.
Enantioselective synthesis of the proposed structure of communiol C, an antibacterial tetrahydrofuran derivative produced by Podospora communis, and its stereoisomers revealed that the genuine stereochemistry of communiol C should be 3R, 5R, and 6S. Two other structurally related metabolites of the same microbial origin, communiols A and B, were also synthesized based on the revised stereochemistry. 相似文献
13.
Kenji Mori 《Tetrahedron letters》2007,48(32):5609-5611
Absolute configuration of gomadalactones A (1), B (2) and C (3), the pheromone components of the white-spotted longicorn beetle (Anoplophora malasiaca) was assigned as (1S,4R,5S)-1, (1R,4R,5R)-2 and (1S,4R,5S,8S)-3 by comparing their published CD spectra with those of (1R,5R)-(+)-4,4,8-trimethyl-3-oxabicyclo[3.3.0]oct-7-ene-2,6-dione (4) and (1S,5R,8S)-(+)-4,4,8-trimethyl-3-oxabicyclo[3.3.0]octane-2,6-dione (5) prepared from (R)-(−)-carvone (6). 相似文献
14.
A novel and highly convenient process is described for the asymmetric synthesis of polyhydroxylated pyrrolizidine alkaloids, (+)-alexine [(1R,2R,3R,7S,7aS)-3-hydroxymethyl-1,2,7-trihydroxypyrrolizidine] and (−)-7-epi-alexine [(1R,2R,3R,7R,7aS)-3-hydroxymethyl-1,2,7-trihydroxypyrrolizidine], as the potent glycosidase inhibitors by featuring the efficient and stereodefined elaboration of the functionalized pyrrolidine derivatives, which were, in turn, prepared via stereoselective manipulation of the homochiral allyl alcohol precursors derived from l-xylose. 相似文献
15.
A common strategy for the total syntheses of the protected l-arabino- and l-ribo-C18-phytosphingosine (8 and 9, respectively), HCl salts of ent-2-epi-jaspine B (ent-6) and 3-epi-jaspine B (7) with efficient use of both flexible building blocks 26 and 27 was achieved. The key step of this approach was [3,3]-sigmatropic rearrangement of allylic trichloroacetimidate 21 and thiocyanate 22, which were derived from the known 2,3:5,6-di-O-isopropylidene-d-mannofuranose 18 as the source of chirality. The side chain functionality was installed utilizing a Wittig reaction. 相似文献
16.
Masahiko Isaka Somporn Palasarn Sujinda Sommai Sukitaya Veeranondha Kitlada Srichomthong Palangpon Kongsaeree Samran Prabpai 《Tetrahedron》2017,73(12):1561-1567
Seven new lanostane triterpenoids, astraeusins M–Q (1–5), 26-epi-artabotryol C1 (6), and 26-epi-astrasiaone (7), together with seventeen known compounds (8–24), were isolated from the food mushroom Astraeus asiaticus. The C-26 configuration of artabotriol C1 and astrasiaone, originally reported as 26R (6 and 7, respectively), was revised to be 26S (16 and 17, respectively). Astraeusin M (1) exhibited antimalarial activity against Plasmodium falciparum K1 with an IC50 value of 3.0 μg/mL. 相似文献
17.
Youichi Iimura Yukinori Hotta Chiyoko Fukabori Kin-Ichi Tadano Tetsuo Suami 《Journal of carbohydrate chemistry》2013,32(1):147-152
Recently, we have completed a total synthesis of swainsonine (l), (1S,2S,8R,8aR)-1,2,8-trihydroxyoctahydroindolizine, which exhibits remarkable physiological effects such as an α-mannosidase inhibitory activity, an immunoregulating activity and so on. In order to elucidate a relationship between structures and physiological activities, a congener of swainsonine has been synthesized. In this communication, we wish to report a synthesis of (-)-8-epi-swainsonine (2) and (-)-1,8-di-epi-swainsonine (2) from methyl 3-acetamido-2-0-acetyl-4,6-0-benzylidene-3-deoxy-α-D-glucopyranoside (4) and methyl 3-acetamido-2-0-acetyl-3-deoxy-4,6-di-0-mesyl-α-glucopyranoside-(14), respectively. 相似文献
18.
Biotransformation of (+)-(1R,2S)-fenchol by the larvae of Spodoptera litura was carried out. Substrate was converted to three new terpenoids, (+)-(1R,2S)-10-hydroxyfenchol, (+)-(1R,2R,3S)-8-hydroxyfenchol and (−)-(1S,2S,6S)-6-exo-hydroxyfenchol, and one known terpenoid, (−)-(1R,2R,3R)-9-hydroxyfenchol. These structures were established by NMR, IR, specific rotation and mass spectral studies. 相似文献
19.
《Tetrahedron: Asymmetry》2006,17(5):819-821
(1S,2R,5R,7S)-2-Hydroxy-exo-brevicomin ent-1 was synthesized from 1,2;5,6-di-O-isopropylidene-d-glucose in seven steps. The key reaction in our synthesis is the formation of bicyclic ketal 7 under acid mediated acetal exchange of a 1,2-acetonide of d-glucose derivative 6. 相似文献
20.
Márta Palkó Gabriella Benedek Enikő Forró Edit Wéber Mikko Hänninen Reijo Sillanpää Ferenc Fülöp 《Tetrahedron: Asymmetry》2010,21(8):957-961
(1R,2S,6R)-2-Amino-6-hydroxycyclooctanecarboxylic acid (?)-10 was synthesized from (1R,2S)-2-aminocyclooct-5-enecarboxylic acid (+)-2 via an iodolactone intermediate, while (1R,2S,3R,4S)-2-amino-5,6-dihydroxycyclooctanecarboxylic acid (?)-12 was prepared by using the OsO4-catalyzed oxidation of Boc-protected amino ester (?)-5. The stereochemistry and relative configurations of the synthesized compounds were determined by 1D and 2D NMR spectroscopy (based on 2D NOE cross-peaks and 3J(H,H) coupling constants) and X-ray crystallography. 相似文献