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1.
Keck GE Kraft MB Truong AP Li W Sanchez CC Kedei N Lewin NE Blumberg PM 《Journal of the American Chemical Society》2008,130(21):6660-6661
Highly potent bryostatin analogues which contain the complete bryostatin core structure have been synthesized using a pyran annulation approach as a key strategic element. The A ring pyran was assembled using a pyran annulation reaction between a C1-C8 hydroxy allylsilane and an aldehyde comprising C9-C13. This pyran was transformed to a new hydroxy allylsilane and then coupled with a preformed C ring aldehyde subunit in a second pyran annulation, with concomitant formation of the B ring. This tricyclic intermediate was elaborated to bryostatin analogues which displayed nanomolar to subnanomolar affinity for PKC, but displayed properties indistinguishable from a phorbol ester in a proliferation/attachment assay. 相似文献
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Wender PA Dechristopher BA Schrier AJ 《Journal of the American Chemical Society》2008,130(21):6658-6659
The step-economical synthesis of a new class of bryostatin analogues that contain the complete oxycarbocyclic core ring system of the bryostatin natural products is reported. These agents are convergently assembled via a highly efficient, functional-group-tolerant, and stereoselective Prins-driven macrocyclization. These tetrahydropyranyl B-ring analogues are among our most potent and efficacious analogues to date, exhibiting nanomolar and picomolar activities in protein kinase C affinity assays as well as in cellular antiproliferation assays. 相似文献
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《Acta Crystallographica. Section C, Structural Chemistry》2017,73(6):447-450
The peptide di‐l ‐phenylalanine (FF) has emerged as a highly potent candidate for the development of novel nanomaterials. The unprotected peptide was dissolved in 1,1,1,3,3,3‐hexafluoropropan‐2‐ol (HFIP) mixed with tetrahydrofuran (THF) and single crystals of the THF monosolvate, C18H20N2O3·C4H8O, were grown by slow evaporation in a `vial‐in‐closed‐bottle' system. THF is a molecule that can only act as a hydrogen‐bond acceptor. Thus, the hydrogen‐bond patterns observed in the crystal structures at 100 and 299 K are different compared to that of crystals grown from water and methanol [Mason et al. (2014). ACS Nano. 8 , 1243–1253]. 相似文献
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The NiBr(2)(dppe)-Zn system effectively catalyzes the [2+2+2] cocyclotrimerization of arynes with allenes, leading to 10-methylene-9,10-dihydrophenanthrenes in moderate to good yields. The cocyclotrimerization is highly selective with only the internal double bond of the allenes being involved in the reaction. 相似文献
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The flavanone glycoside naringin hydrate is widely abundant in various citrus plants. As an ongoing effort toward the exploitation of natural products as scaffolds for chemical diversification at readily accessible positions, we have prepared a series of analogues of naringin in which the 6-hydroxyl group of the beta-d-glucopyranosyl subunit was converted to sulfonamides, amides, urethanes, and secondary and tertiary amines via the corresponding 6-amino derivative using a solution-phase parallel array protocol. 相似文献
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Ingo Janser Caitlyn M. Vortolomei Ranjith K. Meka Courtney A. Walsh Romy F.J. Janser 《Comptes Rendus Chimie》2013,16(7):660-664
Ethacrynic acid and a series of its analogues were synthesized and subsequently evaluated for their inhibitory effect on jack bean urease. Ethacrynic acid showed, even at low concentrations, very potent inhibitory activity against the enzyme. For ethacrynic acid, the inhibition potential increased with increasing preincubation time of ethacrynic acid and enzyme, whereas for some other compounds a higher preincubation time lead to a significant reduction of their activity. We could demonstrate that the α,β-unsaturated carbonyl unit of our compounds is mandatory to inhibit the enzyme, possibly due to its ability to bind to cysteine residues in the active site of the jack bean urease. 相似文献
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Ram Sagar 《Tetrahedron》2004,60(50):11399-11406
The Morita-Baylis-Hillman (MBH) reaction of p-nitrobenzaldehyde with C (6) acyl protected enuloside 1 in the presence of TiCl4/TBAI yielded highly diastereoenriched C-3-branched deoxysugar derivative or MBH adduct 1′a in high yield, while reactions of unprotected enuloside 2a and C (6) alkyl protected enulosides 2d-e with p-nitrobenzaldehyde under the same conditions afforded the adducts 2′a and 2′d-e, respectively, in low yield with moderate selectivity. Several representative aromatic and aliphatic aldehydes were selected to undergo MBH reaction with 1 to give their respective adducts in very good yield with a very high diastereoselectivity. A plausible mechanism based on the assumption of a Zimmerman-Traxler-type transition state was proposed to explain the excellent selectivity observed with adducts derived from 1. The synthetic application of these adducts were shown by their stereoselective reduction to corresponding threo isomers in very good yield. 相似文献
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[reaction: see text] Effective nickel-catalyzed cocycloaddition of nonconjugated diynes with conjugated diynes yields polysubstituted arylalkynes in good to excellent yields with high regio- and chemoselectivity. 相似文献
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Herein, we report the synthesis of novel ring-expanded bryostatin analogues. By carefully modifying the substrate, a selective and high-yielding Ru-catalyzed tandem enyne coupling/Michael addition was employed to construct the northern fragment. Ring-closing metathesis was utilized to form the 31-membered ring macrocycle of the analogue. These ring-expanded bryostatin analogues possess anticancer activity against several cancer cell lines. Given the difficulty in forming the C16-C17 olefin at a late stage, we also describe our development of a new-generation strategy to access the C7-C27 fragment, containing both the ring B and C subunits. 相似文献
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Synthesis of a tritium-labeled, fipronil-based, highly potent, photoaffinity probe for the GABA receptor 总被引:1,自引:0,他引:1
3-[4-[1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazolo]]-3-(trifluoromethyl)diazirine is a fipronil-based (i.e. fiprole), high-affinity probe for the GABA receptor. For synthesis of the tritium-labeled version of this trifluoromethyldiazirinylfiprole ([(3)H]TDF) the required intermediate, 3-[4-[1-(2,6-dichloro-3-iodo-4-trifluoromethylphenyl)-5-iodopyrazolo]]-3-(trifluoromethyl)diazirine, was prepared in 10 steps from pyrazole and 3,5-dichloro-4-fluorobenzotrifluoride. One of the key transformations was lithiation and subsequent iodination of the 4-(2,2,2-trifluoro-1-hydroxyethyl)pyrazole intermediate. The last step involved reduction of the diiodofiprole with tritium, Pd/C, and triethylamine in ethyl acetate and afforded [(3)H]TDF with a specific activity of 15 Ci/mmol and 99% radiopurity. 相似文献
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Lithiated 2′,3′-O-isopropylidine-5′--methoxymethyl-uridine was found to react with a variety of electrophilic reagents regiospecifically at the C-6 position. The protecting groups of the ribose moiety in the 6-functionalized products were concurrently removed under mild conditions with aqueous trifluoroacetic acid. Consequently, the present method permits simple and general syntheses of 6-substituted uridines. 相似文献
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Andrey A. BerezinPanayiotis A. Koutentis 《Tetrahedron》2011,67(22):4069-4078
Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO4 oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised. 相似文献
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The direct reduction of alcohols using chlorodiphenylsilane as a hydride source in the presence of a catalytic amount of indium trichloride is described. Benzylic alcohols, secondary alcohols, and tertiary alcohols were effectively reduced to give the corresponding alkanes in high yields. A compound bearing both primary and secondary hydroxyl groups was reduced only at the secondary site to afford the primary alcohol after workup with Bu(4)NF. This system showed high chemoselectivity only for the hydroxyl group while not reducing other functional groups that are readily reduced by standard reducing systems. Thus alcohols bearing ester, chloro, bromo, or nitro groups, which are sensitive to LiAlH(4) or Zn/H(+), were selectively reduced only at the hydroxyl sites by the chlorodiphenylsilane/InCl(3) system. NMR studies revealed the reaction course. The hydrodiphenylsilyl ether is initially formed and then, with InCl(3) acting as a Lewis acid, forms an oxonium complex, which accelerates the desiloxylation with donation of the hydrogen to the carbon. 相似文献
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The first series of oxcarbazepine analogues, starting from readily-available materials and through a high-yielding five-step sequence based on palladium catalysis, is reported. The so-obtained compounds incorporate not only a variety of substituents in both of the aryl rings comprising the framework of an oxcarbazepine, but also involve the more challenging palladium-catalysed coupling of a number of heteroaromatic substrates. The addition of small amounts of water in some of the metal-catalysed processes showed a beneficial effect, highly increasing the selectivity of such reactions. 相似文献
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Cycloisomerization of a variety of omega-aryl-1-alkynes, where omega = 5 or 6, in the presence of a catalytic amount of GaCl3 provided dihydronaphthalene derivatives or dihydrobenzocycloheptenes, respectively, in high yields. 相似文献
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The s-BuLi-sparteine base combination deprotonated the C-2' position of 1,2,3,4,5-pentamethylazaferrocene and subsequent reaction with a range of electrophiles gave C-2 substituted products in 76-93% yield and approximately 80% ee. The products could be recrystallised to enrich ee's to >90%. Resubjection of the initial addition products ( approximately 80% ee) to the deprotonation conditions led to a kinetic resolution to give products with >90% ee and superior overall yields compared to recrystallisation for the cases where the electrophiles were Ph2CO, MeI and Ph2S2. Transmetallation of the 2-lithiopentamethylazaferrocene ( approximately 80% ee) with ZnCl2 allowed palladium catalysed cross coupling with a variety of C-2 haloaryl, heteroaryl and vinyl groups to give some novel C-2' substituted pentamethylazaferrocene derivatives in 61-77% yield in 80% ee. Potential N,N-chelate ligands were recrystallised to >95% ee. A novel C2-symmetric bis-pentamethylazaferrocene could be synthesised by an iron catalysed oxidative coupling of the enatioenriched C-2 lithio derivative and in the presence of a PhMe-Et2O solvent mixture proceeded in 97% ee. 相似文献