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1.
Bromotyrosine alkaloids dispyrin (1), purpurealidin E (2), and aplysamine-1 (3) isolated from marine sponge, were synthesized from commercially available tyramine (4) as a common starting material. The overall yield was 18%, 39%, and 22% for 1 from 4 in 5 steps, 2 in 5 steps, and 3 in 6 steps, respectively. 相似文献
2.
ZACA-lipase-catalyzed acetylation tandem process has been shown to proceed satisfactorily with either TBS-protected 4-penten-1-ol or 3-buten-1-ol to provide the corresponding enantiomerically pure (R)-2-ethyl-1-alkanols. Either (R)-5 or (R)-6 was converted to 3 in seven steps. The other fragment 4 was synthesized in nine steps from (-)-(S)-citronellol. Conversion of 3 and 4 into 99% pure fluvirucinine A1 was achieved in four steps via amidation-ring closing metathesis, the overall yield in the longest linear sequence being 34% (13 steps). 相似文献
3.
[reaction: see text] Siphonarienolone (1) has been synthesized from siphonarienal (3) in 66% over four steps. Synthesis of 3, in turn, has been achieved in two steps (85% combined yield) from 4, prepared from 3-buten-1-ol in seven steps (23% combined yield). Also, a two-step conversion of 3 into siphonarienone (2) is reported. 相似文献
4.
Felpin FX Girard S Vo-Thanh G Robins RJ Villiéras J Lebreton J 《The Journal of organic chemistry》2001,66(19):6305-6312
An enantiomeric synthesis of six piperidine and pyrrolidine alkaloids, (S)-nornicotine 1, (S)-nicotine 2, (S)-anatabine 3, (S)-N-methylanatabine 4, (S)-anabasine 5, and (S)-N-methylanabasine 6, known as natural products in tobacco, was established from a common chiral homoallylic (S)-3-(1-azido-but-3-enyl)-pyridine 15. An intramolecular hydroboration-cycloalkylation of the homoallylic azide intermediate 15 served as the key step in the pyrrolidine ring formation. A ring closing metathesis reaction (RCM) of a diethylenic amine intermediate (S)-allyl-(1-pyridin-3-yl-but-3-enyl)-carbamic acid benzyl ester 20 served as the key step in the piperidine ring formation. From the commercially available 3-pyridinecarboxaldehyde 13, a short and convenient enantiomeric synthesis of tobacco alkaloids is described: (S)-nornicotine 1 (5 steps, with an overall yield of 70%), (S)-nicotine 2 (6 steps, 65%), (S)-anatabine 3 (8 steps, 30%), (S)-N-methylanatabine 4 (8 steps, 25%), (S)-anabasine 5 (8 steps, 35%), and (S)-N-methylanabasine 6 (8 steps, 25%). 相似文献
5.
Trienes 1 and 3 were obtained in five steps from ethyl 4-acetoxy-3-oxobutanoate and 6-iodo-3-methyl-1,3-hexadiene. Intramolecular Diels-Alder cyclization of 1 and 3 gave tricyclic lactones 2 and 4 as the major products, respectively. The key intermediate 4 was converted in two steps to trans-dihydroconfertifolin (5). 相似文献
6.
R-(+)-pulegone (1) is transformed to (R)-5-methyl-2-(phenylsulfinyl)cyclohexanone (5) (65%, 3 steps). Sulfoxide 5 is converted to R-(-)-3,5-dimethylcyclohex-2-en-1-one (4) (53%, 4 steps) and S-(+)-4 (26%, 3 steps). 相似文献
7.
Synthesis of Isoquinoline-1, 3-Dicarboxylic Acid 总被引:3,自引:0,他引:3
Chiropticalluminescencemeasurementslhavebeenusedforstudyingchiralitydependentmolecularexcited-statedynamic,forstlldyingexcited-stateracemizationkineticsassociatedwithintermolecularchiralrecognitionprocessesinsolution2.Intheseprocesses,therearetwomolecularspecies,lanthanidecomplexes(luminophore)andresolvedtransitioncomplexes(AorA,quencher).Manykindsoftransitionmetalcomplexeshavebeenusedasquencherstoinvestigateinfluenceoftheintermolecularchiralrecognition.However,theluminophoreswereonlyconfined… 相似文献
8.
Lebsack AD Link JT Overman LE Stearns BA 《Journal of the American Chemical Society》2002,124(31):9008-9009
The first total syntheses of higher-order members of the polypyrrolidinoindoline alkaloid family are reported. The synthesis of quadrigemine C (1) and psycholeine (3) begins with synthetic meso-chimonanthine (4), which is synthesized from commercially available oxindole and isatin in 13 steps and 35% overall yield. Double Stille cross coupling of diiodide 7, available in three steps from 4, with vinylstannane 8 produces dibutenanilide 9. Double catalytic asymmetric Heck cyclization of 9 simultaneously installs the two peripheral quaternary stereocenters and desymmetrizes this advanced meso precursor to deliver the chiral, decacyclic intermediate 11 in 62% yield and 90% ee. In two additional steps, 11 is converted to 1, which upon treatment with acid generates 3. The synthesis of quadrigemine C (1), which rigorously confirms its relative and absolute configuration, was executed in 19 linear steps (2% overall yield) from commercially available starting materials. 相似文献
9.
Govender S Mmutlane EM van Otterlo WA de Koning CB 《Organic & biomolecular chemistry》2007,5(15):2433-2440
Readily available 2,2',6,6'-tetramethoxy-1,1'-biphenyl was transformed in 14 synthetic steps into the natural product cardinalin 3 using a bidirectional approach. One of the key steps was the formation of the cis-1,3-dimethylnaphtho[2,3-c]pyran ring. (+/-)-1,1'-[6,6'-Diallyl-5,5'-bis(benzyloxy)-1,1',3,3'-tetramethoxy-2,2'-binaphthalene-7,7'-diyl]diethanol was treated with O(2) in the presence of CuCl(2) and catalytic PdCl(2) to afford 5,5'-bis(benzyloxy)-7,7',9,9'-tetramethoxy-1,1',3,3'-tetramethyl-1H,1'H-8,8'-bibenzo[g]isochromene. Hydrogenation of this compound afforded 7,7',9,9'-tetramethoxy-cis-1,3-cis-1',3'-tetramethyl-3,3',4,4'-tetrahydro-1H,1'H-8,8'-bibenzo[g]isochromene-5,5'-diol in quantitative yield, which was converted in 3 steps to cardinalin 3. 相似文献
10.
11.
Lourdes Santana Marta Teijeira Eugenio Uriarte 《Journal of heterocyclic chemistry》1999,36(1):293-295
(±)-trans-1-[2-(Hydroxymethyl)cyclopentylmethyl]uracil ( 1 ) was prepared in two steps and 56% yield from 2-hydroxymethylcyclopentylmethylamine (7) and 3-methoxy-2-propenoylisocyanate ( 6 ). Isocyanate 6 was prepared from methyl 3-methoxy-2-propenoate in four steps and 38% overall yield. 相似文献
12.
13.
New oxophenylarcyriaflavins were synthesized in a few efficient steps. The key steps involved at first a palladium cross-coupling between the 3-bromo-4-(1H-indol-3-yl)1-methylpyrrole-2,5-dione and the 2-formylphenylboronic acid or a methyl 2-trialkylstannylbenzoate, followed by an intramolecular acylation in a C-2 indolic position. All the sequence was carried out without any indolic protective group. 相似文献
14.
Under the conditions of transfer hydrogenation employing the cyclometalated iridium catalyst (R)-I derived from [Ir(cod)Cl](2), allyl acetate, 4-cyano-3-nitrobenzoic acid, and the chiral phosphine ligand (R)-SEGPHOS, α-methylallyl acetate engages 1,3-propanediol (1a) and 2-methyl-1,3-propanediol (1b) in double carbonyl crotylation from the alcohol oxidation level to deliver the C(2)-symmetric and pseudo-C(2)-symmetric stereopolyads 2a and 3a, respectively, with exceptional control of anti-diastereoselectivity and enantioselectivity. Notably, the polypropionate stereopentad 3a is formed predominantly as 1 of 16 possible stereoisomers. Desymmetrization of 3a is readily achieved upon iodoetherification to form pyran 4. The direct generation of 3a enables a dramatically simplified approach to previously prepared polypropionate substructures, as demonstrated by the synthesis of C19-C27 of rifamycin S (eight steps, originally prepared in 26 steps) and C19-C25 of scytophycin C (eight steps, originally prepared in 15 steps). The present transfer hydrogenation protocol represents an alternative to chiral auxiliaries, chiral reagents, and premetalated nucleophiles in polyketide construction. 相似文献
15.
Indole-3-acetonitrile-4-methoxy-2-C-β-D-glucopyranoside (1), a novel C-glycoside from Isatis indigotica with important cytotoxic activity, has been prepared in ten steps from ethynyl-β-C-glycoside 3 and 2-iodo-3-nitrophenyl acetate 6. Key steps in the synthesis include a Sonogashira coupling and a CuI-mediated indole formation. NMR spectroscopic data for synthetic 1 differs from that reported for the natural product. A revised structure for the natural product, containing an alternate carbohydrate substituent, is proposed. 相似文献
16.
Yi LI Tao ZHANG Yu Lin LI 《中国化学快报》2006,17(2):147-149
~~First Total Synthesis of 6-Oxodendrolasinolide1.For a report on vinyl dithiane regioselectivity and similar reactions, see: (a) W. S. Murphy, S. Wattanasin, J. Chem. Soc, Perkin Trans. 1, 1980, 2678. (b) L. Colombo, C. Gennari, M. Santandrea, et al, J. … 相似文献
17.
Enantioselective synthesis of (-)-cis-clavicipitic acid 总被引:1,自引:0,他引:1
An enantioselective synthetic method for (-)-cis-clavicipitic acid (1) was reported. 1 was obtained in 10 steps (99% ee and 20% overall yield) from 1H-indole-3-carboxylic acid methyl ester (9) via asymmetric phase-transfer catalytic alkylation and diastereoselective Pd(II)-catalyzed intramolecular aminocyclization as key steps. 相似文献
18.
An enantioselective synthesis of the natural antiproliferative agent quinocarcin was achieved by the directed condensation of optically active alpha-amino aldehyde intermediates. Condensation of the N-protected alpha-amino aldehyde 1, prepared in eight steps (19% yield) from (R,R)-pseudoephedrine glycinamide, with the C-protected alpha-amino aldehyde derivative 2, prepared in seven steps (34% yield) from (R,R)-pseudoephedrine glycinamide, afforded the corresponding imine in quantitative yield. Without isolation, direct treatment of this imine intermediate with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and hydrogen cyanide led to cleavage of the fluorenylmethoxycarbonyl (Fmoc) protective group followed by addition of cyanide (Strecker reaction) to form the bis-amino nitriles 3 as a mixture of diastereomers, in 91% yield. Treatment of the diastereomers 3 with trimethylsilyl cyanide and zinc chloride in 2,2,2-trifluoroethanol at 60 degrees C led to stepwise cyclization to form the tetracyclic product 4 (42% yield from 1 and 2). The latter intermediate was transformed into (-)-quinocarcin (1) in five steps (45% yield). The yield of quinocarcin was 19% from 1 and 2 (7 steps), and 4% from pseudoephedrine glycinamide (15 steps). 相似文献
19.
以茴香醛保护氨基方法得到的β-构型的四乙酰基氨基葡萄糖盐酸盐(1)为原料, 采用三氯乙酰基(TCA)、三氯乙酰亚胺酯基(TCI)和乙硫基(SEt)保护体系, 经五步反应以产率40.5%得到完全β-构型保护的β-(1→3)-2-脱氧-2-氨基葡二糖7, 又经两步合成得到保护的β-(1→3)-2-脱氧-2-氨基葡二糖受体8, 共八步合成了保护的β-(1→3)-2-脱氧-2-氨基葡三糖10, 总产率为27%. 以上化合物均为未知. 同时, 还得到了用以合成β-(1→4)-保护的氨基葡四糖的受体6. 采用该保护体系可以高选择性地、较高产率地合成氨基寡糖. 相似文献
20.
Katharine E. Lambson Christopher A. Dacko Jeffrey M. McNeill Novruz G. Akhmedov Björn C.G. Söderberg 《Tetrahedron》2019,75(49):130714
Dilemmaones A-C are naturally occurring tricyclic indole alkaloids possessing a unique hydroxymethylene or methoxymethylene substituent at the C2 position of the indole core and a C6–C7 fused cyclopentanone. Dilemmaone B has been prepared in 5 steps from 5-methylindan-1-one, and dilemmaone A has been prepared in 3 steps from a common precursor, 6-bromo-5-methyl-7-nitroindan-1-one. In both syntheses, key steps include a Kosugi-Migita-Stille cross coupling and a reductive cyclization using hydrogen gas and a transition metal catalyst. 相似文献