- Tandem Oxidative Dearomatizing Spirocyclizations of Propargyl Guanidines and Ureas
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Treatment of propargyl ureas or guanidines with iodosobenzene diacetate results in an oxidative tandem amination/etherification dearomatizing spirocyclization. This transformation leads directly to the complete framework of the Leucetta alkaloids, spiroca
- Singh, Ravi P.,Das, Jayanta,Yousufuddin, Muhammed,Gout, Delphine,Lovely, Carl J.
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- Rhodium-Catalyzed β-Dehydroborylation of Silyl Enol Ethers: Access to Highly Functionalized Enolates
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An efficient rhodium-catalyzed β-dehydroborylation of aldehyde-derived silyl enol ethers (SEEs) with bis(pinacolato)diboron (B2pin2) is disclosed. The borylation reactions proceeded well with alkyl- and aryl-substituted SEEs, affording a wide array of valuable functionalized β-boryl silyl enolates with high efficiency and excellent stereoselectivity. Moreover, the borylated products, through versatile carbon–boron bond transformations, were readily converted into diverse synthetically useful molecules, including α-hydroxy ketones, functionalized SEEs, and gem-difunctionalized aldehydes.
- Li, Jie,Li, Ruoling,Yang, Wen,Zhao, Pei,Zhao, Wanxiang
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supporting information
p. 9580 - 9585
(2021/12/14)
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- Organocatalytic Enantioselective Pictet-Spengler Approach to Biologically Relevant 1-Benzyl-1,2,3,4-Tetrahydroisoquinoline Alkaloids
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(Figure Presented) A general procedure for the synthesis of 1-benzyl-1,2,3,4-tetrahydroisoquinolines was developed, based on organocatalytic, regio- and enantioselective Pictet-Spengler reactions (86-92% ee) of N-(o-nitrophenylsulfenyl)-2-arylethylamines with arylacetaldehydes. The presence of the o-nitrophenylsulfenyl group, together with the MOM-protection in the catechol part of the tetrahydroisoquinoline ring system, appeared to be a productive combination. To demonstrate the versatility of this approach, 10 biologically and pharmaceutically relevant alkaloids were prepared using (R)-TRIP as the chiral catalyst: (R)-norcoclaurine, (R)-coclaurine, (R)-norreticuline, (R)-reticuline, (R)-trimemetoquinol, (R)-armepavine, (R)-norprotosinomenine, (R)-protosinomenine, (R)-laudanosine, and (R)-5-methoxylaudanosine.
- Ruiz-Olalla, Andrea,Würdemann, Martien A.,Wanner, Martin J.,Ingemann, Steen,Van Maarseveen, Jan H.,Hiemstra, Henk
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p. 5125 - 5132
(2015/05/27)
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- Synthesis of (±)-Bakuchiol via a pot-economy approach
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A rapid synthetic route toward (±)-Bakuchiol is presented in 29% overall yield. After the sole all-carbon quaternary carbon center is created via allylboration of 2-aryl acetaldehyde, a “Pot-Economy” approach including mesylation, elimination, and desilylation was realized in the presence oftBuOK under ambient temperature to provide (±)-Bakuchiol.
- Huang, Meng-Yuan,Chen, Long,Li, Ruoxi,Ji, Xueshun,Hong, Ran
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p. 715 - 720
(2014/11/08)
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- 2-Morpholinoisoflav-3-enes as flexible intermediates in the synthesis of phenoxodiol, isophenoxodiol, equol and analogues: Vasorelaxant properties, estrogen receptor binding and Rho/RhoA kinase pathway inhibition
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Isoflavone consumption correlates with reduced rates of cardiovascular disease. Epidemiological studies and clinical data provide evidence that isoflavone metabolites, such as the isoflavan equol, contribute to these beneficial effects. In this study we developed a new route to isoflavans and isoflavenes via 2-morpholinoisoflavenes derived from a condensation reaction of phenylacetaldehydes, salicylaldehydes and morpholine. We report the synthesis of the isoflavans equol and deoxygenated analogues, and the isoflavenes 7,4′-dihydroxyisoflav-3-ene (phenoxodiol, haganin E) and 7,4′-dihydroxyisoflav-2-ene (isophenoxodiol). Vascular pharmacology studies reveal that all oxygenated isoflavans and isoflavenes can attenuate phenylephrine-induced vasoconstriction, which was unaffected by the estrogen receptor antagonist ICI 182,780. Furthermore, the compounds inhibited U46619 (a thromboxane A2 analogue) induced vasoconstriction in endothelium-denuded rat aortae, and reduced the formation of GTP RhoA, with the effects being greatest for equol and phenoxodiol. Ligand displacement studies of rat uterine cytosol estrogen receptor revealed the compounds to be generally weak binders. These data are consistent with the vasorelaxation activity of equol and phenoxodiol deriving at least in part by inhibition of the RhoA/Rho-kinase pathway, and along with the limited estrogen receptor affinity supports a role for equol and phenoxodiol as useful agents for maintaining cardiovascular function with limited estrogenic effects.
- Tilley, Andrew J.,Zanatta, Shannon D.,Qin, Cheng Xue,Kim, In-Kyeom,Seok, Young-Mi,Stewart, Alastair,Woodman, Owen L.,Williams, Spencer J.
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experimental part
p. 2353 - 2361
(2012/05/07)
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- Synthetic libraries of tyrosine-derived bacterial metabolites
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The preparation of a collection of 131 small molecules, reminiscent of families of long chain N-acyl tyrosines, enamides and enol esters that have been isolated from heterologous expression of environmental DNA (eDNA) in Escherichia coli, is reported. The synthetic libraries of N-acyl tyrosines and their 3-keto counterparts were prepared via solid-phase routes, whereas the enamides and enol esters were synthesized in solution-phase.
- Georgiades, Savvas N.,Clardy, Jon
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supporting information; experimental part
p. 3117 - 3121
(2009/04/03)
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- Synthesis of methyl 1-O-(4-hydroxymethamphetaminyl)-α-D- glucopyranouronate
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For the purpose of the direct characterization of the intact conjugated form in the urine of a methamphetamine (MA) abuser, 4-hydroxymethamphetamine (4-OHMA) glucuronate, corresponding to one of the metabolites of MA, was synthesized from the commercially available methyl 4-hydroxyphenylacetate.
- Nakajima, Rika,Ono, Machiko,Aiso, Sadakazu,Akita, Hiroyuki
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p. 684 - 687
(2007/10/03)
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- Synthesis of long-chain fatty acid enol esters isolated from an environmental DNA clone
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(Matrix presented) Long-chain fatty acid enol ester 1 is the major metabolite of a new family of small molecules isolated from the heterologous expression of environmentally derived DNA. A versatile synthesis of 1, in which an aromatic acetaldehyde is O-a
- Brady, Sean F.,Clardy, Jon
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p. 121 - 124
(2007/10/03)
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