- Ytterbium-Catalyzed Intramolecular [3 + 2] Cycloaddition based on Furan Dearomatization to Construct Fused Triazoles
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The 1,2,3-triazole-containing polycyclic architecture widely exists in a broad spectrum of synthetic bioactive molecules, and the development of expeditious methods to synthesize these skeletons remains a challenging task. In this work, the catalytic cyclization of biomass-derived 2-furylcarbinols with an azide to form fused triazoles is described. This approach takes advantage of a single catalyst Yb(OTf)3 and operates via a furfuryl-cation-induced intramolecular [3 + 2] cycloaddition/furan ring-opening cascade.
- Xu, Xiaoming,Zhong, Ying,Xing, Qingzhao,Gao, Ziwei,Gou, Jing,Yu, Binxun
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supporting information
p. 5176 - 5181
(2020/07/14)
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- Iridium-Catalyzed Enantioselective Hydrogenation of Oxocarbenium Ions: A Case of Ionic Hydrogenation
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Ionic hydrogenation has not been extensively explored, but is advantageous for challenging substrates such as unsaturated intermediates. Reported here is an iridium-catalyzed hydrogenation of oxocarbenium ions to afford chiral isochromans with high enantioselectivities. A variety of functionalities are compatible with this catalytic system. In the presence of a catalytic amount of the Br?nsted acid HCl, an α-chloroether is generated in situ and subsequentially reduced. Kinetic studies suggest first-order kinetics in the substrate and half-order kinetics in the catalyst. A positive nonlinear effect, together with the half kinetic order, revealed a dimerization of the catalyst. Possible reaction pathways based on the monomeric iridium catalyst were proposed and DFT computational studies revealed an ionic hydrogenation pathway. Chloride abstraction and the cleavage of dihydrogen occur in the same step.
- Lin, Zhenyang,Sun, Yongjie,Wang, Heng,Wen, Jialin,Yang, Tilong,Zhang, Xumu
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supporting information
p. 6108 - 6114
(2020/03/04)
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- Enantioselective synthesis of tetrahydroisoquinoline derivatives via chiral-at-metal rhodium complex catalyzed [3+2] cycloaddition
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An asymmetric [3+2] cycloaddition of C,N-cyclic azomethine imines with α,β-unsaturated 2-acyl imidazoles catalyzed by a chiral-at-metal rhodium complex has been developed. The corresponding C-1-substituted tetrahydroisoquinoline derivatives were obtained in high yields (>90%) with excellent stereoselectivities (up to 99% ee and >20?:?1 dr). The reaction can be conducted on a gram-scale using a low catalyst loading (0.5 mol%) with high yield and selectivity.
- Qurban, Saira,Du, Yu,Gong, Jun,Lin, Shao-Xia,Kang, Qiang
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supporting information
p. 249 - 252
(2019/01/04)
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- Synthesis of 5,6-Dihydropyrazolo[5,1-a]isoquinoline and Ethyl (Z)-3-Acetoxy-3-tosylpent-4-enoate through Tertiary-Amine-Catalyzed [3+2] Annulation
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The 1,4-diazabicyclo[2.2.2]octane (DABCO) catalyzed divergent [3+2] annulation of C,N-cyclic azomethine imines with δ-acetoxyallenoates was developed; 5,6-dihydropyrazolo[5,1-a]isoquinolines and ethyl (Z)-3-acetoxy-3-tosylpent-4-enoates were afforded in moderate to good yields in a one-pot manner under mild conditions. This annulation reaction provides a highly efficient method to construct dinitrogen-fused heterocycles and ethyl (Z)-3-acetoxy-3-tosylpent-4-enoates at the same time.
- Lei, Yu,Xing, Jiao-Jiao,Xu, Qin,Shi, Min
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p. 3486 - 3490
(2016/07/28)
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- Phosphane-Catalyzed [3+3] Annulation of C,N-Cyclic Azomethine Imines with Ynones: A Practical Method for Tricyclic Dinitrogen-Fused Heterocycles
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A phosphane-catalyzed [3+3] annulation of azomethine imines with ynones has been developed. Under mild reaction conditions, the reaction proceeds smoothly to afford tricyclic dinitrogen-fused heterocyclic compounds in moderate to excellent yields with moderate to excellent stereoselectivies. Using a chiral phosphine as the catalyst, the reaction could work to give the cycloadduct in moderate yield with moderate enantioselectivity. (Figure presented.) .
- Li, Zhen,Yu, Hao,Liu, Yang,Zhou, Leijie,Sun, Zhanhu,Guo, Hongchao
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supporting information
p. 1880 - 1885
(2016/07/06)
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- Scaffold Diversity through a Branching Double-Annulation Cascade Strategy: Iminium-Induced One-Pot Synthesis of Diverse Fused Tetrahydroisoquinoline Scaffolds
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A branching double-annulation cascade (BDAC) strategy for diverse and complex fused THIQ scaffolds via a highly reactive iminium-induced one-pot double-cyclization sequence involving Pictect-Spengler-type cyclization has been developed for the first time. The salient features of this protocol are that it allows direct and rapid access to unprecedented diverse fused THIQ skeletons, is metal/catalyst free, has a cleaner reaction profile, provides good to excellent yields, and is a convenient approach. This catalyst-free domino process facilitates the double annulation with a variety of scaffold building agents via two C-N and one C-X (X = C, N, O) bond formation in a single step under uniform reaction conditions. Furthermore, we reveal an unusual dual BDAC sequence leading to N-N-linked isoquinoline dimer.
- Sharada, Duddu S.,Shinde, Anand H.,Patel, Srilaxmi M.,Vidyacharan, Shinde
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p. 6463 - 6471
(2016/08/16)
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- A metal-free cyclic iminium induced one-pot double annulation cascade: Access to dihydroisoquinolinium (DHIQ) salts
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A reactive cyclic iminium induced one-pot Groebke-Blackburn-Bienayme (GBB) double annulation cascade (DAC) for the synthesis of skeletally diverse DHIQ salts has been described. The key features of this protocol are transition-metal and solvent-free, mild reaction conditions, robust method, one-step construction of two privileged heterocyclic rings, clean reaction profile and operational simplicity.
- Sagar,Nagarjuna Babu, Venkata,Shinde, Anand H.,Sharada, Duddu S.
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supporting information
p. 10366 - 10370
(2016/11/18)
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- A Phosphine-Catalyzed Novel Asymmetric [3+2] Cycloaddition of C,N-Cyclic Azomethine Imines with δ-Substituted Allenoates
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Catalytic asymmetric [3+2] cycloadditions of C,N-cyclic azomethine imines with δ-substituted allenoates have been developed in the presence of (S)-Me-f-KetalPhos, affording functionalized tetrahydroquinoline frameworks in good yields with high diastereo- and good enantioselectivities under mild condition. The substrate scope has been also examined. This is the first time that δ-substituted allenoates have been applied as a δ,γ-C-C bond participated C 2 synthon in asymmetric synthesis. Another round: Catalytic asymmetric [3+2] cycloaddition of C,N-cyclic azomethine imines with δ-substituted allenoates have been developed in the presence of (S)-Me-f-KetalPhos, affording functionalized tetrahydroquinoline frameworks in good yields with high diastereo- and good enantioselectivities under mild conditions. This is the first example applying δ-substituted allenoates as C 2 synthons in asymmetric δ,γ-C-C bond formation.
- Wang, De,Lei, Yu,Wei, Yin,Shi, Min
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p. 15325 - 15329
(2016/02/18)
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- A facile one-pot protocol for the synthesis of tetrazolyl-tetrahydroisoquinolines via novel domino intramolecular cyclization/Ugi-azide sequence
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A facile one-pot, four-component domino reaction between 2-(2-bromoethyl)benzaldehyde, isocyanide, amine, and azide for the synthesis of tetrazolyl-tetrahydroisoquinoline derivatives has been developed. The reaction sequence involves intramolecular replacement of halide by iminium nitrogen followed by Ugi-azide reaction. The reaction is catalyst/additive free and takes place under ambient conditions with short reaction times to furnish products in good to excellent yields.
- Shinde, Anand H.,Archith,Malipatel, Srilaxmi,Sharada, Duddu S.
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supporting information
p. 6821 - 6826
(2015/01/09)
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- In situ generation of nucleophilic allenes by the gold-catalyzed rearrangement of propargylic esters for the highly diastereoselective formation of intermolecular C(sp3)-C(sp2) bonds
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New perspectives, in particular for the synthesis of isochromane derivatives (see scheme), are provided by the title reaction. Excellent diastereoselectivites are achieved in this reaction which proceeds through a gold-catalyzed 1,3-acyloxy migration. In some cases exclusively the Z isomer is detected. Copyright
- Yu, Yang,Yang, Weibo,Rominger, Frank,Hashmi, A. Stephen K.
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supporting information
p. 7586 - 7589
(2013/07/26)
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- CuBr2 catalyzed bromination/oxidation of isochromans to benzaldehyde derivatives
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A series of isochromans were oxidized and brominated by using 1.2 equiv of CuBr2 in CH3CN at reflux to give the corresponding bromo benzaldehydes in moderate yields. A plausible mechanism for this transformation has been suggested.
- Zhou, Mei-Yan,Kong, Shan-Shan,Zhang, Ling-Qiong,Zhao, Ming,Duan, Jin-Ao,Ou-Yang, Zhen,Wang, Min
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supporting information
p. 3962 - 3964
(2013/07/25)
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- H3PW12O40at the[bmim][FeCl4]: A green catalytic system for alkoxymethylation of alcohols and their one-pot interconversion to acetates and TMS-ethers
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12-Tungstophosphoric acid immobilized on [bmim][FeCl4] was found to be an efficient catalyst for chemoselective methoxymethylation and ethxoymethylation of alcohols and also one-pot conversion of MOM- or EOM-ethers to their corresponding acetates and TMS-ethers under thermal conditions and microwave irradiation. These procedures were simple, rapid and the corresponding products were obtained in high yields. The catalyst exhibited remarkable reactivity and was reusable.
- Mohammadpoor-Baltork,Moghadam,Tangestaninejad,Mirkhani,Khosropour,Mirjafari
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experimental part
p. 513 - 524
(2012/06/16)
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- [InCl4]: An efficient catalyst-medium for alkoxymethylation of alcohols and their interconversion to acetates and TMS-ethers
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A simple, green and chemoselective method for methoxymethylation and ethoxymethylation of primary and secondary alcohols using a Lewis acidic room temperature ionic liquid, [C4mim][InCl4], as catalyst and reaction medium under ambient temperature, microwave and ultrasonic irradiations is reported. In this catalytic system, the corresponding MOM-and EOM-ethers are obtained in excellent yields and in short reaction times. Furthermore, this catalytic system was used for mild and efficient transformations of these protected alcohols to their corresponding acetates and trimethylsilyl ethers under thermal conditions and microwave and ultrasonic irradiations.
- Mohammadpoor-Baltork, Iraj,Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Khosropour, Ahmad Reza,Mirjafari, Arsalan
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experimental part
p. 568 - 579
(2012/05/05)
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- Copper-catalyzed enantioselective additions to oxocarbenium ions: Alkynylation of isochroman acetals
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We have developed an enantioselective, copper(I)-catalyzed addition of terminal alkynes to racemic isochroman acetals. This method is one of the first transition-metal-catalyzed approaches to enantioselective additions to prochiral oxocarbenium ions. In this reaction, TMSOTf is used to form the oxocarbenium ion in situ under conditions compatible with simultaneous formation of the chiral copper acetylide. By using a bis(oxazoline) ligand, good yields and enantioselectivities are observed for a variety of enantioenriched 1-alkynyl isochromans.
- Maity, Prantik,Srinivas, Harathi D.,Watson, Mary P.
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supporting information; experimental part
p. 17142 - 17145
(2011/12/13)
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- Highly efficient and selective methoxymethylation of alcohols and phenols catalyzed by high-valent tin(IV) porphyrin
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An efficient and selective method for methoxymethylation of alcohols and phenols with formaldehyde dimethyl acetal (FDMA) catalyzed by electron deficient tin(IV)tetraphenylporphyrinato trifluoromethanesulfonate, [SnIV(TPP)(OTf)2], is
- Gharaati, Shadab,Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj,Kosari, Farshid
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experimental part
p. 1995 - 2000
(2011/01/07)
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- Highly efficient and selective methoxymethylation of alcohols and phenols catalyzed by reusable ZrO(OTf)2 under solvent-free conditions
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Different primary, secondary, and tertiary alcohols were efficiently converted to their corresponding methoxymethyl ethers with formaldehyde dimethyl acetal in the presence of catalytic amounts of ZrO(OTf)2 at room temperature. Phenols were als
- Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj,Khajehzadeh, Mostafa
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experimental part
p. 641 - 647
(2011/05/04)
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- High-valent [SnIV(Br8TPP)(OTf)2] as a highly efficient and reusable catalyst for selective methoxymethylation of alcohols and phenols: The effect of substituted bromines on the catalytic activity
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High-valent tin(IV)octabromotetraphenylporphyrinato trifluoromethanesulfonate, [SnIV(Br8TPP)(OTf)2], was used for selective methoxymethylation of alcohols and phenols with formaldehyde dimethyl acetal (FDMA) at room temper
- Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj,Khajehzadeh, Mostafa,Kosari, Farshid,Araghi, Mehdi
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experimental part
p. 238 - 243
(2010/04/04)
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- A mild and efficient method for the methoxymethylation and acetylation of alcohols promoted by benzyltriphenylphosphonium tribromide
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A mild and efficient method for the conversion of alcohols to their corresponding methoxymethyl ethers and acetates using benzyltriphenylphosphonium tribromide (BTPTB) as catalyst is described. All reactions were performed under completely heterogeneous reaction conditions in good to high yields.
- Shirini, Farhad,Imanzadeh, Gholam Hossein,Mousazadeh, Seyyed Ali Reza,Mohammadpoor-Baltork, Iraj,Abedin, Masoumeh
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experimental part
p. 1187 - 1190
(2011/10/05)
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- Melamine trisulfonic acid (MTSA): A new efficient catalyst for the chemoselective methoxymethylation of alcohols
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Melamine trisulfonic acid, which is easily prepared by the reaction of melamine with neat chlorosulfonic acid, is able to efficiently catalyze the chemoselective methoxymethylation of alcohols with dimethoxymethane (DMM). All reactions were performed unde
- Shirini, Farhad,Zolfigol, Mohammad Ali,Albadi, Jalal
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experimental part
p. 910 - 914
(2010/05/01)
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- A facile method for the rapid and selective deprotection of methoxymethyl (MOM) ethers
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We describe a rapid and efficient method for selective deprotection of methoxymethyl (MOM) ethers using ZnBr2 and n-PrSH, which completely removed MOM from diverse MOM ethers of primary, secondary, and tertiary alcohols or phenol derivatives. The deprotection takes less than ten minutes with both high yield and selectivity in the presence of other protecting groups. In addition, the rapid deprotection of MOM ethers of tertiary hydroxyls in high yield with no epimerization allows MOM to be a suitable protecting group for tertiary alcohols.
- Han, Jae Hyun,Kwon, Young Eun,Sohn, Jeong-Hun,Ryu, Do Hyun
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experimental part
p. 1673 - 1677
(2010/04/04)
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- H3PW12O40 - A selective, environmentally benign, and reusable catalyst for the preparation of methoxymethyl and ethoxymethyl ethers and their deprotections under mild conditions
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Different types of primary and secondary alcohols were efficiently transformed to their corresponding methoxymethyl (MOM) and ethoxymethyl (EOM) ethers in the presence of catalytic amounts of H3PW 12O40 at room temperature under solvent-free conditions. Selective protection of primary and secondary alcohols in the presence of phenols and tertiary alcohols was achieved by this method. Deprotection of these ethers to their parent alcohols was also performed using this catalyst in ethanol under reflux conditions. We have also found that primary and secondary MOM- and EOM-ethers are selectively deprotected in the presence of phenolic and tertiary ones, methyl and benzyl ethers, esters, and trimethylsilyl ethers by this catalyst. The notable advantages of this protocol are high yields, short reaction times, easy work-up, non-toxicity, easy availability and handling, eco-friendly, and reusability of the catalyst.
- Mohammadpoor-Baltork, Iraj,Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mirjafari, Arsalan
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p. 831 - 840
(2008/12/21)
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- N,N,N′,N′-tetrabromobenzene-1,3-disulfonamide and poly(N-bromo-N-ethyl-benzene-1,3-disulfonamide) as efficient catalysts for the methoxymethylation of alcohols under solvent-free conditions
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Methoxymethylation of a variety of alcohols was performed using formaldehyde dimethyl acetal in the presence of N,N,N′,N′- tetrabromobenzene-1,3-disulfonamide [TBBDA] and poly(N-bromo-N-ethyl-benzene-1, 3-disulfonamide) [PBBS] as catalysts at room tempera
- Ghorbani-Vaghei, Ramin,Zolfigol, Mohammad Ali,Amiri, Mostafa,Veisi, Hojat
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experimental part
p. 632 - 635
(2009/05/07)
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- Metal hydrogen sulfates catalyzed methoxymethylation of alcohols under solvent-free conditions
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Methoxymethylation of a variety of alcohols was performed by using formaldehyde dimethoxy acetal in the presence of metal hydrogen sulfate M(HSO4)n at room temperature and solvent-free conditions. The methoxymethyl ethers (MOM-ethers
- Niknam, Khodabakhsh,Zolfigol, Mohammad Ali,Shayegh, Mohsen,Zare, Reza
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p. 1067 - 1073
(2008/02/13)
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- HYDROXY-PROTECTING REAGENT AND METHOD OF PROTECTING HYDROXY WITH THE SAME
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The present invention relates to a method of protecting a hydroxyl group, which includes reacting a hydroxyl group-containing compound with a compound represented by the formula (I) : wherein R is a phenyl group optionally having substituent(s), an alkyl
- -
-
Page/Page column 10-11
(2008/06/13)
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- Efficient and selective formation of mixed acetals by Nafion-H SAC-13 silica nanocomposite solid acid catalyst
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Various types of hydroxy compounds can readily be converted to the corresponding mixed acetals with dialkoxymethanes in the presence of SAC-13 solid superacid. The transformation is almost instantaneous, product acetals are isolated in good to excellent yields, and the catalyst can be reused with minor loss of activity. Comparative studies were also carried out with p-toluenesulfonic acid and BF3·OEt2.
- Ledneczki, Istvan,Molnar, Arpad
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p. 3683 - 3690
(2007/10/03)
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- New efficient method of alkoxymethyl etherification of secondary alcohols
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A new efficient method of MOM etherification of secondary alcohols using 2-(chloromethyl)-3,5-dioxahex-1-ene (Okahara's reagent) is reported.
- Watanabe, Yosuke,Ikemoto, Tetsuya
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p. 5795 - 5797
(2007/10/03)
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- Scandium trifluoromethanesulfonate as a recyclable catalyst for efficient methoxymethylation of alcohols
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Scandium triflate [Sc(OTf)3] has been found to be a recyclable catalyst for mild highly efficient methoxymethylation of a variety of alcohols using formaldehyde dimethyl acetal (FDMA).
- Karimi, Babak,Ma'mani, Leyla
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p. 6051 - 6053
(2007/10/03)
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- TiO2/SO42-, an efficient catalyst for the methoxymethylation of alcohols
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Methoxymethylation of primary and secondary alcohols with dimethoxymethane has afforded the corresponding methoxymethyl ethers in good to high yields in the presence of TiO2/SO42- solid superacid.
- Jin, Tong-Shou,Guo, Jun-Jie,Yin, Ya-Hui,Zhang, Su-Ling,Li, Tong-Shuang
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p. 188 - 189
(2007/10/03)
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- Envirocat EPZGR Catalysed Methoxymethylation of Alcohols
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Envirocat EPZGR is an efficient reusable heterogenous catalyst for the methoxymethylation of alcohols. The isolation of pure products by simple filtration and evaporation is an important feature of this method.
- Bandgar,Hajare,Wadgaonkar
-
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- Sulfated zirconia as an efficient catalyst for the methoxymethylation of alcohols
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Primary and secondary alcohols react with dimethoxymethane in the presence of a catalytic amount of sulfated zirconia to afford the corresponding methoxy methyl ethers (MOM ether) in good to high yields.
- Sarkar, Anjana
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p. 862 - 863
(2007/10/03)
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- One-step synthesis of novel carbonates: Alkoxymethyl carbonates, from alcohols and chloromethyl alkyl ethers using silver carbonate
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A synthesis of the novel carbonates, alkoxymethyl carbonates, is presented, starting with an alcohol. In the presence of silver carbonate, primary and secondary alcohols react with chloromethyl alkyl ethers in N,N-dimethylformamide under mild conditions to give the corresponding alkoxymethyl carbonates in good yields, without forming the alkoxymethyl ethers. The yields of alkoxymethyl carbonates are heavily influenced by the reaction solvent and this method is not applicable to tertiary alcohols. Methoxymethyl carbonate can be removed readily under mild basic or acidic conditions, and selective alkoxide interchange of the methoxymethoxide group occurs under basic conditions.
- Teranishi,Nakao,Komoda,Hisamatsu,Yamada
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p. 176 - 180
(2007/10/02)
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- A One-Step Conversion of p-Methoxybenzyl Ethers into Methoxymethyl Ethers by the Action of Dimethoxymethane in the Presence of Tin(II) Bromide and Bromomethyl Methyl Ether
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The combined use of dimethoxymethane with catalytic amounts of tin(II) bromide and bromomethyl methyl ether cleaves p-methoxybenzyl ethers to give methoxymethyl ethers in good yields.The chemoselective conversion of p-methoxybenzyl ethers in the presence of the benzyl ether function into methoxymethyl ethers has also occurred successfully.
- Oriyama, Takeshi,Kimura, Mikio,Koga, Gen
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p. 885 - 887
(2007/10/02)
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