- The benzyl can be selectively removed by visible light or near visible light. Method for protecting allyl and propargyl group
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The invention provides a method for selectively removing benzyl, allyl and propargyl protecting groups by visible light or near visible light, namely a substrate containing benzyl, allyl or propargyl protecting groups. The method has the advantages of simple operation, safe and clean visible light or near visible light as excitation conditions, cheap and easily available reagents, high reaction yield, high reaction chemistry and regional selectivity, and is suitable for selective removal of benzyl, allyl and propargyl protecting groups in various substrates.
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Paragraph 0028
(2021/10/16)
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- Catalytic Aza-Wacker Annulation: Tuning Mechanism by the Activation Mode of Amide and Enantioselective Syntheses of Melinonine-E and Strychnoxanthine
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An unprecedented N-substituent of the amide was found to be crucial for the successful annulation to establish 2-azabicyclo[3.3.1]nonane and other ring skeletons in good yield. The novel catalytic aza-Wacker annulation methodology was further illustrated
- Xie, Changmin,Luo, Jisheng,Zhang, Yuping,Huang, Sha-Hua,Zhu, Lili,Hong, Ran
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supporting information
p. 2386 - 2390
(2018/04/30)
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- A process for preparing β - phenyl ethyl alcohol
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The invention discloses a method for preparing beta-phenethyl alcohol. According to the method, acetic acid-3-butene-1-alcohol ester and 1,3-butadiene are adopted as raw materials, and the preparation of beta-phenethyl is finished by adopting Diels-Alder, hydrolysis and dehydrogenation reactions. lewis acid supported by fullerol as a carrier is adopted as the catalyst for the Diels-Alder reaction, the atom utilization rate is high, the total yield can reach 87%-95%, the purity of products can reach 99.92wt%-99.98wt%, and an oxidation reaction process and a high-pressure hydrotreatment reaction process are not adopted, so that the production process is safe and environmentally friendly.
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Paragraph 0014; 0048-0049; 0054-0055; 0060; 0061; 0066; 0067
(2017/11/01)
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- Model studies on the synthesis of madangamine alkaloids. Assembly of the macrocyclic rings
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Using simplified model derivatives, the assembly of the macrocyclic rings of madangamines, including the 13- and 14-membered D rings of madangamines C-E, the all-cis-triunsaturated 15-membered D ring of madangamine A, and the (Z,Z)-unsaturated 11-membered E ring common to madangamines A-E, has been studied.
- Proto, Stefano,Amat, Mercedes,Pérez, Maria,Ballette, Roberto,Romagnoli, Federica,Mancinelli, Andrea,Bosch, Joan
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supporting information; experimental part
p. 3916 - 3919
(2012/09/22)
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- PS-COD and PS-9-BBN: Polymer-supported reagents for solution-phase parallel synthesis
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(Chemical Equation Presented) 1,5-Cyclooctadiene was deprotonated under LICKOR conditions and reacted with Merrifield resin to afford an immobilized cyclooctadiene in high yield. This polymer is effective as a halogen scavenger, while hydroboration leads to a supported 9-BBN analogue. The latter exhibits similar regioselectivity to 9-BBN in olefin hydroboration.
- Revell, Jefferson D.,Doerner, Barbara,White, Peter D.,Ganesan
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p. 831 - 833
(2007/10/03)
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- Selective conversion of enol ethers into alcohols in the presence of alkenes using Hg(OAc)2-NaBH4
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Alkyl enol ethers derived from aldehydes undergo selective oxymercuration-demercuration with aqueous Hg(OAc)2-NaBH4 in the presence of an alkene in good to excellent yield. This method allows the survival of mono-, trans and cis di-, and tri-substituted alkenes as well as cyclic alkenes.
- Crouch, R. David,Mehlmann, John F.,Herb, Brian R.,Mitten, Jeffrey V.,Dai, H. George
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p. 559 - 561
(2007/10/03)
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- Total syntheses of (±)-agelasimine-A, (±)-agelasimine-B, and (±)-purino-diterpene and the structure of diacetylagelasimine-A
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A full account is given of the first racemic syntheses of agelasimine-A (1a) and agelasimine-B (2a), adenine-related bicyclic diterpenoids isolated from the marine sponge Agelas mauritiana. Central synthetic features include a highly stereoselective const
- Ohba, Masashi,Kawase, Nobuo,Fujii, Tozo
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p. 8250 - 8257
(2007/10/03)
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- Hydroborations, reductions and reductive iodinations using BHI2:N(C2H5)2Ph complex
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The BHI2:N(C2H5)2Ph complex, prepared by the reaction of BH3:N(C2H5)2Ph with I2, is useful for hydroboration of alkenes, reduction of amides, iodination of alcohols, reductive iodination of carboxylic acids, aldehydes and ketones. Selective hydroboration of monosubstituted olefin over disubstituted olefinic moiety and terminal olefin over internal alkyne moiety have been achieved using this reagent. Carboxylic esters and nitriles are not affected by this reagent. Selective hydroboration of 1-alkenes and selective reductive iodination of cyclohexanone are achieved in the presence of ester and nitrile functional groups.
- Kishan Reddy,Periasamy
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p. 8329 - 8336
(2007/10/02)
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- Free-radical based cycloalkanol synthesis and annulation from thioacetal precursors
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A general procedure for the synthesis of diverse cyclopentanols via free-radical cyclization of unsaturated 1,3-oxathiolanes and 1,3-oxathiolan-5-ones is described.The scope of these reactions, including preliminary rate studies that indicate that the 1,3-oxathiolan-5-ones cyclize at a useful rate (1.4*106 M-1s-1 at 80 deg C), has been examined.This permits the rapid assembly, by intramolecular annulation, of various additional ring systems, including bicyclooctanols, bicyclononanols, and bicyclooctanols for use in total synthesis. Key words: radical cyclization, oxathiolanes, oxathiolanones.
- Yadav, Veejendra,Fallis, Alex G.
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p. 779 - 789
(2007/10/02)
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- Oxidative Cleavage of Carbon-Silicon Bonds by Dioxygen: Catalysis by a Flavin-Dihydronicotinamide Redox System
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Carbon-silicon bonds in alkyloxy- or fluoro-silanes readily undergo cleavage by dioxygen (molecular oxygen), catalysed by tetra-acetylriboflavin (5-10 molpercent) in the presence of N-benzyl-1,4-dihydronicotinamide as reductant, together with fluoride ions as an essential additive.
- Tamao, Kohei,Hayashi, Takashi,Ito, Yoshihiko
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p. 795 - 797
(2007/10/02)
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- DIRECT CONVERSION OF ALKENES INTO METHYL-SUBSTITUTED CYCLOPROPANES USING AN ORGANOIRON ETHYLIDENE TRANSFER REAGENT
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(η5-C5H5)(CO)2FeCH(CH3)SPh (8) serves as a quite useful reagent for the transfer of ethylidene groups to alkenes to give methyl-substituted cyclopropanes in good yields.The reaction is accomplished by allowing 8 to react with an alkylating agent such as trimethyloxonium tetrafluoroborate or methyl fluorosulfonate in the presence of the alkene substrate.The active ethylidene transfer reagent is apparently a sulfonium salt which is too reactive to be isolated under normal conditions.In all csases, cyclopropanes are obtained stereospecifically with respect to the configuration of the starting alkenes, and with certain classes of substrates such as cis-disubstituted alkenes, the reaction also occurs with very high syn-stereoselectivity.
- Kremer, Kenneth A. M.,Helquist, Paul
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p. 231 - 252
(2007/10/02)
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- OXIDATIVE CLEAVAGE OF SILICON-CARBON BONDS IN ORGANOSILICON FLUORIDES TO ALCOHOLS
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Certain functional silyl groups have been shown to be synthetically equivalent to the OH group.All of the C-Si bonds in organosilicon fluorides, K2 and RnSiF4-n (n=1,2,3) are cleaved by m-chloroperbenzoic acid (MCPBA) in DMF to give the corresponding alcohols in high yields.Although the reaction with RSiF5(2-) and RSiF3 proceeds without any additive, cleavage of R2SiF2 and R3SiF requires, respectively, a catalytic or excess amount of KF.A triorganoethoxysilane also undergoes similar oxidative cleavage reactions in the presence of an excess amount of KF.The MCPBA-oxidation of exo- and endo-2-norbornyl-silicate and -trifluorosilane proceeds stereospecifically with retention of configuration at carbon.A remarkable solvent effect has been observed in the oxidative cleavage of RSiF3.A plausible mechanism involves a hexacoordinate silicon species in which the organic group intramolecularly migrates from Si to O of the coordinated MCPBA.
- Tamao, K.,Kakui, T.,Akita, M.,Iwahara, T.,Kanatani, R.,et al.
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p. 983 - 990
(2007/10/02)
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- A NOVEL ZIRCONIUM-CATALYZED HYDROALUMINATION OF OLEFINS
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Sterically hindered trialkylalanes, such as triisobutylalane, react with olefins at or below room temperature under the influence of a catalytic amount of Cl2ZrCp2 to effect hydroalumination of the olefins.The reaction can tolerate certain hetero-functional groups, such as OH, SPh and Br, which tend to interfere with previously reported hydroalumination procedures.
- Negishi, Ei-ichi,Yoshida, Tadao
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p. 1501 - 1504
(2007/10/02)
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