- Studies towards the synthesis of FCRR toxin: An expeditious entry into 7-5-6 ring systems via [5+2] oxidopyrylium-alkene cycloaddition
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Synthetic studies towards the diterpene natural product FCRR toxin have been undertaken. An intermolecular [5+2] oxidopyrylium-alkene cycloaddition reaction was employed to construct the 7-5-6 tricyclic framework. The reaction proceeded with very high regio- and stereoselectivity and the bridging ether was reductively cleaved to unmask the carbocycle.
- Murali Krishna,Trivedi
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Read Online
- Cycloaddition of 3-oxidopyrylium: A novel route to functionalized cyclooctanoids from furans
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We report a facile and efficient synthesis of highly functionalized cyclooctanoid derivatives by employing a dimerization reaction of 3-oxidopyrylium ylides. Different substituents are introduced on the dimer and the stereochemical outcome of the resultan
- Krishna, Urlam Murali,Patil, Mahendra P.,Sunoj, Raghavan B.,Trivedi, Girish K.
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Read Online
- A solvent-free catalytic protocol for the Achmatowicz rearrangement
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Reported here is the development of an environmentally friendly catalytic (KBr/oxone) and solvent-free protocol for the Achmatowicz rearrangement (AchR). Different from all previous methods is that the use of chromatographic alumina (Al2O3) allows AchR to proceed smoothly in the absence of any organic solvent and therefore considerably facilitates the subsequent workup and purification with minimal environmental impacts. Importantly, this protocol allows for scaling up (from milligram to gram), recycling of the Al2O3, and integrating with other reactions in a one-pot sequential manner.
- Zhao, Guodong,Tong, Rongbiao
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- 13C NMR analysis of 3,6-dihydro-2 H -pyrans: Assignment of remote stereochemistry using axial shielding effects
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The rational analysis of 13C NMR axial shielding effects has enabled the assignment of remote relative stereochemistry in 3,6-oxygen-substituted 3,6-dihydro-2H-pyrans. Comparison of the 13C NMR shifts of equivalent centers in cis- an
- Bartlett, Mark J.,Northcote, Peter T.,Lein, Matthias,Harvey, Joanne E.
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- Mechanistic insights into the vanadium-catalyzed achmatowicz rearrangement of furfurol
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The Achmatowicz rearrangement is a powerful method for the construction of pyranones from simple furan derivatives. Here, we describe the development of improved reaction conditions and an interrogation into the fate of the metal center during this interesting transformation. The reaction to form the synthetically important lactol, 6-hydroxy-2H-pyran-3(6H)-one (3), proceeds cleanly in the presence of tert-butyl hydroperoxide (TBHP, 2) using low loadings of VO(OiPr)3 as catalyst. The nonaqueous conditions developed herein allow for easy isolation of product 3 and synthetically important derivatives, a key advantage of this new protocol. Detailed experimental, spectroscopic, and kinetic studies along with kinetic modeling of the catalytic cycle support a positive-order dependence in both furfurol and TBHP concentrations, first-order dependence in catalyst (VO(OiPr)3), and a negative dependence on the 2-methyl-2-propanol (4) concentration. 51V-NMR spectroscopic studies revealed that 2-methyl-2-propanol (4) competes with substrates for binding to the metal center, rationalizing its inhibitory effect.
- Ji, Yining,Benkovics, Tamas,Beutner, Gregory L.,Sfouggatakis, Chris,Eastgate, Martin D.,Blackmond, Donna G.
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- Regioselectivity in the palladium-catalyzed addition of carbon nucleophiles to dihydropyran derivatives
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The regioselectivity of Pd-catalyzed malonate or sulfonylacetate addition to dihydropyran derivatives is highly dependent upon the substitution pattern of the dihydropyran nucleus and is governed by electronic, rather than steric factors. In certain instances, subtle steric features also play a role in controlling regioselectivity by altering the conformation of the intermediate η3-allyl Pd-complex.
- Brescia, Marc-Raleigh,Shimshock, Yvonne Class,DeShong, Philip
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- [6+3] Cycloaddition of pentafulvenes with 3-oxidopyrylium betaine: a novel methodology toward the synthesis of 5-8 fused oxabridged cyclooctanoids
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Pentafulvenes undergo a facile [6+3] cycloaddition with 3-oxidopyrylium betaine, generated from the corresponding pyranulose acetate, leading to the formation of 5-8 fused oxabridged cyclooctanoids. The product is formed by a [6+3] cycloaddition, followed
- Krishnan, K. Syam,Sajisha,Anas,Suresh,Bhadbhade, Mohan M.,Bhosekar, Gaurav V.,Radhakrishnan
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Read Online
- Silica gel enables Achmatowicz rearrangement with KBr/oxone under “anhydrous” condition for one-pot functionalization
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Silica gel was found to effectively promote Achmatowicz rearrangement (AchR) using KBr/oxone under near anhydrous condition. This new protocol allows direct functionalization of AchR products in a one-pot manner, effectively reducing the cost, time, and e
- Zhao, Guodong,Tong, Rongbiao
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Read Online
- Palladium-Catalyzed Regioselective and Diastereoselective C-Glycosylation by Allyl-Allyl Coupling
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A Pd-catalyzed C-glycosylation reaction was developed by allyl-allyl coupling process using Achmatowicz rearrangement products as donors and methylcoumarins as acceptors under mild conditions. This method featured regio- and diastereoselectivities, stereo
- Li, Junhao,Zheng, Nan,Duan, Xuelun,Li, Rui,Song, Wangze
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supporting information
p. 846 - 850
(2020/12/13)
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- TRICYCLIC MODULATORS OF PP2A
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Chemical modulators of PP2A, comprising tricyclic sulfonimidamides are disclosed. The compounds are useful in preventing or treating cancer, diabetes, autoimmune disease, solid organ transplant rejection, graft vs host disease, chronic obstructive pulmonary disease (COPD), non-alcoholic fatty liver disease, abdominal aortic aneurysm, chronic liver disease, heart failure, neurodegenerative disease and cardiac hypertrophy. The compounds are of formula (I)
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Page/Page column 207; 209-210
(2021/09/04)
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- Enantioselective 1,3-Dipolar [6+4] Cycloaddition of Pyrylium Ions and Fulvenes towards Cyclooctanoids
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Organocatalytic enantioselective 1,3-dipolar [6+4] cycloadditions of pyrylium ion intermediates with fulvenes promoted by a chiral primary amine catalyst have been developed to proceed in moderate to good yields and high enantioselectivities. The resultant chiral bicyclo[6.3.0]undecane scaffold containing a transannular bridging ether is densely functionalised providing a rigid scaffold for further manipulations. Computational studies give important insights into the role of the primary amine catalyst. Analysis of the reaction shows that the catalytic reaction proceeds in a step-wise manner and rationalises the stereochemical outcome of the reaction. Several stereoselective complexity-generating transformations, facilitated by the diverse functional groups and transannular bridge, are presented, highlighting the versatility of the core towards a number of the cyclooctanoid natural products.
- McLeod, David,Cherubini-Celli, Alessio,Sivasothirajah, Nisanhi,McCulley, Christina H.,Christensen, Mette Louise,J?rgensen, Karl Anker
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supporting information
p. 11417 - 11422
(2020/08/06)
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- Achmatowicz rearrangement enables hydrogenolysis-free gas-phase synthesis of pentane-1,2,5-triol from furfuryl alcohol
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Highly efficient synthesis of pentane-1,2,5 triol, a promising member of biorenewable C5 alcohols, has been achieved by gas-phase hydrogenation of the Achmatowicz intermediate derived from furfuryl alcohol. The hydrogenation was carried out on monocomponent or bicomponent Ni and/or Pt modified mesoporous silica catalysts. The process features the absence of hydrogenolysis of the furan ring and rendered 100% selectivity together with additional green chemistry benefits, such as mild and simpler solvent free technology that operates at atmospheric pressure. The bicomponent Ni/Pt modified mesoporous silica catalysts exhibited the highest catalytic activity, with 10Ni1Pt/KIT-6 being the most active, providing up to 100% conversion.
- Simeonov, Svilen P.,Lazarova, Hristina I.,Marinova, Maya K.,Popova, Margarita D.
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p. 5657 - 5664
(2019/11/05)
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- Biorefinery via Achmatowicz Rearrangement: Synthesis of Pentane-1,2,5-triol from Furfuryl Alcohol
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A new scalable synthesis of pentane-1,2,5-triol from the furanics platform has been developed. Excellent yields of up to 92 % are obtained under flow conditions by using readily available catalysts from the existing pool. The strategy exploits the highly functionalized Achmatowicz product as a key intermediate, thus circumventing problems related to the low reactivity of the parent furfural and furfuryl alcohol. Besides expanding the portfolio of biomass-derived C5 alcohols, this strategy may also be further applied for the establishment of a versatile bio-based chemical platform.
- Simeonov, Svilen P.,Ravutsov, Martin A.,Mihovilovic, Marko D.
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p. 2748 - 2754
(2019/06/24)
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- Method for preparing novel 6-hydroxy-2H-pyran-3-ketone
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The invention belongs to the technical field of organic synthesis, and provides a method for preparing novel 6-hydroxy-2H-pyran-3-ketone. The method comprises the following steps: in an organic solvent, under the action of a tri-isopropanol vanadyl catalyst, using 1.2 equivalent amount of cumene hydroperoxide as an oxidant, catalytically oxidizing the substituted furan methanol compounds to prepare 2-substituted 6-hydroxy-2H-pyran-3-ketone compounds. The preparation condition of the 6-hydroxy-2H-pyran-3-ketone product is mild, and the product yield is not less than 61%. The preparation methodhas the advantages of mild reaction conditions, environmental protection, and high reaction efficiency, and is more suitable for large-scale production requirements. The prepared 6-hydroxy-2H-pyran-3-ketone compound has potential physiological activity and can be converted into various saccharides.
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Paragraph 0018; 0019; 0020
(2019/01/23)
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- Design, Synthesis, and Phenotypic Profiling of Pyrano-Furo-Pyridone Pseudo Natural Products
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Natural products (NPs) inspire the design and synthesis of novel biologically relevant chemical matter, for instance through biology-oriented synthesis (BIOS). However, BIOS is limited by the partial coverage of NP-like chemical space by the guiding NPs. The design and synthesis of “pseudo NPs” overcomes these limitations by combining NP-inspired strategies with fragment-based compound design through de novo combination of NP-derived fragments to unprecedented compound classes not accessible through biosynthesis. We describe the development and biological evaluation of pyrano-furo-pyridone (PFP) pseudo NPs, which combine pyridone- and dihydropyran NP fragments in three isomeric arrangements. Cheminformatic analysis indicates that the PFPs reside in an area of NP-like chemical space not covered by existing NPs but rather by drugs and related compounds. Phenotypic profiling in a target-agnostic “cell painting” assay revealed that PFPs induce formation of reactive oxygen species and are structurally novel inhibitors of mitochondrial complex I.
- Christoforow, Andreas,Wilke, Julian,Binici, Aylin,Pahl, Axel,Ostermann, Claude,Sievers, Sonja,Waldmann, Herbert
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supporting information
p. 14715 - 14723
(2019/09/06)
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- Catalytic Oxidation of Alcohols Using a 2,2,6,6-Tetramethylpiperidine-N-hydroxyammonium Cation
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The oxidation of alcohols to aldehydes, ketones, and carboxylic acids is reported using 2,2,6,6-tetramethylpiperidine-4-acetamido-hydroxyammonium tetrafluoroborate as a catalyst in conjunction with sodium hypochlorite pentahydrate as a terminal oxidant. The reaction is generally complete within 30–120 min using an acetonitrile/water mix as the solvent, and no additives are required. Product yields are good to excellent and of particular note is that the methodology can be used to access aryl α-trifluoromethyl ketones.
- Miller, Shelli A.,Bisset, Kathryn A.,Leadbeater, Nicholas E.,Eddy, Nicholas A.
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supporting information
p. 1413 - 1417
(2019/01/04)
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- Two catalytic protocols for Achmatowicz rearrangement using cyclic diacyl peroxides as oxidants
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In situ generated bromonium-catalyzed and visible-light photocatalytic Achmatowicz rearrangements of furfuryl alcohols using cyclic diacyl peroxides as oxidants are described. Both protocols feature broad substrate scope, excellent functional group tolera
- Wei, Congyin,Zhao, Rong,Shen, Zhihong,Chang, Denghu,Shi, Lei
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supporting information
p. 5566 - 5569
(2018/08/17)
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- Palladium-Catalyzed [3 + 2]-C-C/N-C Bond-Forming Annulation
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The synthesis of bi- and tricyclic structures incorporating pyrrolidone rings is disclosed, starting from resonance-stabilized acetamides and cyclic α,β-unsaturated-γ-oxycarbonyl derivatives. This process involves an intermolecular Tsuji-Trost allylation/intramolecular nitrogen 1,4-addition sequence. Crucial for the success of this bis-nucleophile/bis-electrophile [3 + 2] annulation is its well-defined step chronology in combination with the total chemoselectivity of the former step. When the newly formed annulation product carries a properly located o-haloaryl moiety at the nitrogen substituent, a further intramolecular keto α-arylation can join the cascade, thereby forming two new cycles and three new bonds in the same synthetic operation.
- Liu, Yang,Mao, Zhongyi,Pradal, Alexandre,Huang, Pei-Qiang,Oble, Julie,Poli, Giovanni
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supporting information
p. 4057 - 4061
(2018/07/15)
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- Enantioconvergent Biocatalytic Redox Isomerization
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Alcohol dehydrogenases can act as powerful catalysts in the preparation of optically pure γ-hydroxy-δ-lactones by means of an enantioconvergent dynamic redox isomerization of readily available Achmatowicz-type pyranones. Imitating the traditionally metal-
- Liu, Yu-Chang,Merten, Christian,Deska, Jan
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supporting information
p. 12151 - 12156
(2018/09/11)
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- Synthesis and Applications of (ONO Pincer)Ruthenium-Complex-Bound Norvalines
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Two (ONO pincer)ruthenium-complex-bound norvalines, Boc-[Ru(pydc)(terpy)]Nva-OMe (1; Boc=tert-butyloxycarbonyl, terpy=terpyridyl, Nva=norvaline) and Boc-[Ru(pydc)(tBu-terpy)]Nva-OMe (5), were successfully synthesized and their molecular structures and absolute configurations were unequivocally determined by single-crystal X-ray diffraction. The robustness of the pincer Ru complexes and norvaline scaffolds against acidic/basic, oxidizing, and high-temperature conditions enabled us to perform selective transformations of the N-Boc and C-OMe termini into various functional groups, such as alkyl amide, alkyl urea, and polyether groups, without the loss of the Ru center or enantiomeric purity. The resulting dialkylated Ru-bound norvaline, n-C11H23CO-l-[Ru(pydc)(terpy)]Nva-NH-n-C11H23 (l-4) was found to have excellent self-assembly properties in organic solvents, thereby affording the corresponding supramolecular gels. Ru-bound norvaline l-1 exhibited a higher catalytic activity for the oxidation of alcohols by H2O2 than parent complex [Ru(pydc)(terpy)] (11 a).
- Isozaki, Katsuhiro,Yokoi, Tomoya,Yoshida, Ryota,Ogata, Kazuki,Hashizume, Daisuke,Yasuda, Nobuhiro,Sadakane, Koichiro,Takaya, Hikaru,Nakamura, Masaharu
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p. 1076 - 1091
(2016/04/20)
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- Iridium-Catalyzed Dynamic Kinetic Isomerization: Expedient Synthesis of Carbohydrates from Achmatowicz Rearrangement Products
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A highly stereoselective dynamic kinetic isomerization of Achmatowicz rearrangement products was discovered. This new internal redox isomerization provided ready access to key intermediates for the enantio- and diastereoselective synthesis of a series of naturally occurring sugars. The nature of the de novo synthesis also enables the preparation of both enantiomers.
- Wang, Hao-Yuan,Yang, Ka,Bennett, Scott R.,Guo, Sheng-Rong,Tang, Weiping
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p. 8756 - 8759
(2015/11/27)
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- Mechanochemically Initiated Achmatowicz Rearrangement
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The Achmatowicz rearrangement converts furfuryl alcohols, obtainable from renewable carbohydrates, into 6-hydroxy-2H-pyrane-3(6H)-ones, which are versatile intermediates for organic synthesis. We describe here the first examples of a solvent-free mechanochemical Achmatowicz rearrangement. Furfuryl alcohols were prepared from furfurals using mechanochemically initiated reductions and Reformatsky reactions. Mechanochemical reaction conditions for the Achmatowicz rearrangement of the obtained furfuryl alcohols were optimized and applied to a series of derivatives, yielding the corresponding rearrangement products in yields of 39 to 95%. GRAPHICAL ABSTRACT.
- Falenczyk, Carolin,P?lloth, Benjamin,Hilgers, Petra,K?nig, Burkhard
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p. 348 - 354
(2015/10/29)
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- Expeditious metal-free access to functionalized polycyclic acetals under mild aqueous conditions
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A facile approach for the synthesis of furopyrans and bicyclic bisacetals under mild aqueous conditions is described. This potentially green, diversity oriented approach involves cascade Michael addition and cycloacetalization of pyranones and 1,3-dicarbo
- Kasare, Sanghratna,Bankar, Siddheshwar K.,Ramasastry
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supporting information
p. 4284 - 4287
(2014/11/08)
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- Pd-catalyzed allylic alkylation cascade with dihydropyrans: Regioselective synthesis of furo[3,2- c ]pyrans
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A regioselective palladium-catalyzed allylic alkylation cascade forms furo[3,2-c]pyrans from various cyclic β-dicarbonyl bis-nucleophiles and 3,6-dihydro-2H-pyran bis-electrophiles. The combination of allylic carbonate and anomeric siloxy leaving groups in the dihydropyran substrate allows control of the many regiochemical possibilities in this reaction. Annulation proceeds stereoconvergently to give cis-fused furopyrans from either cis- or trans-substituted starting material.
- Bartlett, Mark J.,Turner, Claire A.,Harvey, Joanne E.
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supporting information
p. 2430 - 2433
(2013/07/05)
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- Discovery of inhibitors of the wnt and hedgehog signaling pathways through the catalytic enantioselective synthesis of an iridoid-inspired compound collection
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Cousins you can count on: An iridoid-inspired compound collection was synthesized efficiently by the resolution of cyclic enones in an asymmetric cycloaddition with azomethine ylides. The collection contained novel potent inhibitors of the Wnt and Hedgehog signaling pathways. Copyright
- Takayama, Hiroshi,Jia, Zhi-Jun,Kremer, Lea,Bauer, Jonathan O.,Strohmann, Carsten,Ziegler, Slava,Antonchick, Andrey P.,Waldmann, Herbert
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supporting information
p. 12404 - 12408
(2013/12/04)
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- Using water, light, air and spirulina to access a wide variety of polyoxygenated compounds
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A new set of completely green methods utilising air, light, water and spirulina to transform readily accessible furan substrates into a diverse range of synthetically useful polyoxygenated motifs commonly found in natural products is presented herein. The Royal Society of Chemistry 2012.
- Noutsias, Dimitris,Alexopoulou, Ioanna,Montagnon, Tamsyn,Vassilikogiannakis, Georgios
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supporting information; experimental part
p. 601 - 604
(2012/04/23)
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- Toward the synthesis of modified carbohydrates by conjugate addition of propane-1,3-dithiol to α,β-unsaturated ketones
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Selected 5-substituted derivatives 4 of 1,1-diethoxy-5-hydroxypent-3-yn-2- one were treated with propane-1,3-dithiol under various conditions. The unprotected hydroxy ketones underwent cyclization during the dithiol addition and gave the corresponding 3-(diethoxymethyl)-2-oxa-6,10-dithiaspiro[4.5]decan- 3-ols 5 in 80-90% yield as the only products (Schemea 3 and Tablea 1). These products can be regarded as partly modified carbohydrates in the furanose form. When the benzyl-protected analogues 10-Bn of the 1,1-diethoxy-5-hydroxypent-3- yn-2-one derivatives were treated with the same dithiol, however, no cyclization occurred; instead the corresponding 3-{2-[(benzyloxy)methyl]-1,3-dithian-2-yl}- 1,1-diethoxypropan-2-one derivatives 11-Bn were formed in good yield (up to 99%; Table 4). These 1,3-dithianes were and are in the process of being converted to a number of new carbohydrate analogues, and here are reported high-yield syntheses of functionalized molecules 17 belonging to the 5,5-diethoxy-1,4- dihydroxypentan-2-one family of compounds (Table 7), via 15-Bn (Table 5) and 16-Bn (Table 6 and Scheme 8).
- Valdersnes, Stig,Apeland, Ingrid,Flemmen, Guri,Sydnes, Leiv K.
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p. 2099 - 2122
(2013/02/22)
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- SUBSTITUTED DIAMINOCARBOXAMIDE AND DIAMINOCARBONITRILE PYRIMIDINES, COMPOSITIONS THEREOF, AND METHODS OF TREATMENT THEREWITH
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Provided herein are Diaminopyrimidine Compounds having the following structures: wherein R1, R2, R3, and R4 are as defined herein, compositions comprising an effective amount of a Diaminopyrimidine Compound, and methods for treating or preventing liver fibrotic disorders or a condition treatable or preventable by inhibition of a JNK pathway.
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Page/Page column 77
(2012/11/07)
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- Scope and limitations of the photooxidations of 2-(α-Hydroxyalkyl) furans: Synthesis of 2-hydroxy-exo -brevicomin
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Photooxygenation of 2-(α-hydroxyalkyl)furans at 5 °C in MeOH followed by in situ reduction affords, in one synthetic operation, 6-hydroxy-3(2H)-pyranones and/or 5-hydroxy-2(5H)-furanones. The relative ratio of the final products is highly dependent on the substitution of the starting furan substrate. Photooxygenation of 2-(α,β-dihydroxyalkyl)furans followed by in situ reduction and ketalization with acid rapidly provides the 6,8-dioxabicyclo[3.2.1]oct-3-en-2-one framework. This new methodology was successfully applied to the synthesis of 2-hydroxy-exo-brevicomin.(Figure Presented)
- Noutsias, Dimitris,Kouridaki, Antonia,Vassilikogiannakis, Georgios
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supporting information; experimental part
p. 1166 - 1169
(2011/05/06)
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- Total synthesis of gelsemoxonine
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The first total synthesis of gelsemoxonine (1) has been accomplished. Divinylcyclopropane-cycloheptadiene rearrangement of the highly functionalized substrate was successfully applied to assemble the spiro-quaternary carbon center connected to the bicyclic seven-membered core structure. A one-pot isomerization reaction of the α,β-unsaturated aldehyde to the saturated ester via the TMSCN-DBU reagent combination allowed a facile diastereoselective introduction of the latent nitrogen functionality of the unique azetidine moiety.
- Shimokawa, Jun,Harada, Takaaki,Yokoshima, Satoshi,Fukuyama, Tohru
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supporting information; experimental part
p. 17634 - 17637
(2011/12/16)
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- Visible photostability of some ruthenium and platinum phthalocyanines in water and in the presence of organic substrates
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Water-soluble, metal-tetrasubstituted phthalocyanines (-SO3H, MPcS and -COOH, MPcC) of platinum and ruthenium were synthesized and their photostability to visible light irradiation was determined. For the ruthenium phthalocyanines, the characte
- Carchesio, Manuela,Tonucci, Lucia,D'Alessandro, Nicola,Morvillo, Antonino,Boccio, Piero Del,Bressan, Mario
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experimental part
p. 499 - 508
(2011/03/18)
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- Photooxygenation of furans in water and ionic liquid solutions
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Photooxygenation of differently functionalized furans is investigated in aqueous solutions and in ionic liquids [emim]Br and [bmim]BF4. The reaction is generally selective and the final products derive from rearrangement of the intermediate endoperoxides, depending mainly on the polarity and/or nucleophilic nature of the solvent.
- Astarita, Anna,Cermola, Flavio,Dellagreca, Marina,Iesce, Maria Rosaria,Previtera, Lucio,Rubino, Maria
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scheme or table
p. 2030 - 2033
(2010/06/15)
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- Asymmetric total synthesis of the iridoid β-glucoside (+)-geniposide via phosphine organocatalysis
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Phosphine-catalyzed [3 + 2] cycloaddition of ethyl-2, 3-butadienoate with enone (S)-3b occurs with high levels of regio- and stereocontrol to deliver the c/s-fused cyclopenta[c]pyran 4 characteristic of the iridoid family of natural products. Cycloadduct 4 was converted to the iridoid glycoside (+)-geniposide in 10 steps.
- Jones, Regan A.,Krische, Michael J.
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supporting information; experimental part
p. 1849 - 1851
(2009/09/06)
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- Practical, scalable, high-throughput approaches to η3- pyranyl and η3-pyridinyl organometallic enantiomeric scaffolds using the achmatowicz reaction
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(Figure Presented) A unified strategy for the high-throughput synthesis of multigram quantities of the η3-oxopyranyl- and η3-oxopyridinylmolybdenum complexes TpMo(CO)2(η 3-oxopyranyl) and TpMo(CO)2(η3- oxopyridinyl) is described (Tp = hydridotrispyrazolylborato). The strategy uses the oxa- and aza-Achmatowicz reaction for the preparation of these organometallic enantiomeric scaffolds, in both racemic and high enantiopurity versions.
- Coombs, Thomas C.,Lee IV, Maurice D.,Wong, Heilam,Armstrong, Matthew,Cheng, Bo,Chen, Wenyong,Moretto, Alessandro F.,Liebeskind, Lanny S.
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p. 882 - 888
(2008/09/18)
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- Synthesis of the seed germination stimulant 3-methyl-2H-furo[2,3-c]pyran-2-ones utilizing direct and regioselective Ti-crossed aldol addition
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3-Methyl-2H-furo[2,3-c]pyran-2-ones 1 and 2, a unique and remarkable seed germination stimulant, and its analogue were synthesized using direct and regioselective Ti-crossed aldol addition between dihydro-2H-pyran-3(4H)-ones and methyl pyruvate as the key step, followed by furanone formation.
- Nagase, Ryohei,Katayama, Mayumi,Mura, Hiroaki,Matsuo, Noritada,Tanabe, Yoo
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p. 4509 - 4512
(2008/09/21)
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- Synthesis of furanylalkyl hex- and pentenopyranosid-4-uloses
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A few novel furanylalkyl hex- and pentenopyranones have been synthesized from the corresponding hexenopyranosides or hydroxymethylfurfural. In the hexose series, the reactions proceeded through monosilylation of the primary alcohol followed by oxidation of secondary alcohols. The pentenopyranones have been obtained by glycosidation of hydroxymethylfurfural oxidation product.
- Yaya, Soro,Sorho, Siaka,Cottier, Louis,Descotes, Gerard
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p. 117 - 121
(2007/10/03)
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- The first de novo-designed antagonists of the human NK2 receptor
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The de novo molecular design program SPROUT has been used in conjunction with a molecular model to produce a molecular template for a new class of NK2 receptor antagonist. An efficient, stereocontrolled synthesis of a small series of molecules,
- Ali, Mohammed A.,Bhogal, Nirmala,Findlay, John B. C.,Fishwick, Colin W. G.
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p. 5655 - 5658
(2007/10/03)
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- Titanium silicalite 1 (TS-1) catalyzed oxidative transformations of furan derivatives with hydrogen peroxide
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The oxidation of furan derivatives with titanium silicalite 1 (TS-1) and hydrogen peroxide is described. Oxidation products are identified and possible reaction pathways are discussed. It is shown that the oxidation of these compounds occurs via epoxidation of one of the furan double bonds. The initially formed epoxides immediately undergo rearrangement, furans yielding unsaturated 1,4-dicarbonyl compounds and furfuryl alcohols yielding 6-hydroxy-2H-pyran-3(6H) -ones. The latter compounds originate from cyclization of intermediate enedione alcohols. The presented method is particularly useful for the oxidation of 2,5-dimethylfuran to 3-hexene-2,5-dione and the conversion of furfuryl alcohol to 6-hydroxy-2H-pyran-3(6H)-one, a versatile synthon in organic synthesis.
- Wahlen, Joos,Moens, Bart,De Vos, Dirk E.,Alsters, Paul L.,Jacobs, Pierre A.
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p. 333 - 338
(2007/10/03)
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- Studies toward the synthesis of natural and unnatural dienediynes. Part 2: A practical approach to functionalised cyclopentenones
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The dienediyne natural products contain a functionalised dihydroxylated cyclopentane motif. A critical evaluation of the methods for the preparation and rearrangements of pyranones to give 4,5-dihydroxylated cyclopentenones is presented. (C) 2000 Elsevier Science Ltd.
- Caddick,Khan,Frost,Smith,Cheung,Pairaudeau
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p. 8953 - 8958
(2007/10/03)
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- Synthesis of functionalised cyclopentenones via rearrangement of pyranones
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Substituted functionalised cyclopentenones could be obtained via base-mediated isomerisation of pyranones. (C) 2000 Elsevier Science Ltd.
- Caddick, Stephen,Cheung, Steven,Frost, Lisa M.,Khan, Safraz,Pairaudeau, Garry
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p. 6879 - 6882
(2007/10/03)
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- (2+4)-Cycloaddition with singlet oxygen. 17O-investigation of the reactivity of furfuryl alcohol endoperoxide
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In earlier work, the use of furfuryl alcohol as a specific singlet oxygen acceptor was proposed because of the high ratio between the rate constants of chemical reaction and physical quenching. In contrast to furfuryl aldehyde, a number of products are formed by this type II photooxidation of furfuryl alcohol. These products may be derived from the endoperoxide of furfuryl alcohol as a common intermediate. The present work focuses on the reactivity of this endoperoxide that was marked specifically by the use of 17O2 as a source for singlet oxygen. The analyses of the stable products, their yields and their labeling distribution reveal a strong solvent effect on the primary reaction pathways, and nucleophilic substitution reactions leading to hydroperoxide intermediates are dominant.
- Braun, André M.,Dann, Hans,Gassmann, Ernst,Gerothanassis, Ioannis,Jakob, Laurent,Kateva, Jordanka,Martinez, Claudia G.,Oliveros, Esther
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p. 868 - 874
(2007/10/03)
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- Montmorillonite K-10 clay catalysed glycosidation of 1-O-acetyl-2,3-dideoxy-DL-pent-2-enopyrano-4-ulose
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The O-glycosidation reaction of 1-O-acetyl-2,3-dideoxy-DL-pent-2-enopyran-4-ulose catalysed by the environmentally accepted and inexpensive industrial catalyst Montmorillonite K-10 clay with variety of alcohols in high yield is reported.
- Shanmugam,Nair
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p. 3007 - 3013
(2007/10/03)
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- HYPERVALENT IODINE-INDUCED RING ENLARGEMENT OF FURAN DERIVATIVES INTO PYRAN-3(6H)-ONES
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Hypervalent iodine reagents react with 2-furylcarbinols effecting an oxidative ring enlargement to pyranones.The outcome of the reactions depends on the presence of water in the medium and on the pH value.
- Mico, Antonella de,Margarita, Roberto,Piancatelli, Giovanni
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p. 325 - 326
(2007/10/02)
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- The binary reagent PhI(OAc)2-Mg(ClO4)2: a SET induced ring enlargement of furan derivatives into pyranones
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The binary reagent PhI(OAc)2-Mg(ClO4)2 is very efficient for a high conversion of (2-furyl)-1-alcohols into puranones. The reaction mechanism can be explained in terms of a SET process, with the generation of a cation radical as key intermediate.
- De Mico,Margarita,Piancatelli
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p. 3553 - 3556
(2007/10/02)
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- The Intramolecular Enyne Diels-Alder Reaction. Stereoselective Construction of Tricyclic Dioxadienones and Mechanistic Outline
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4-Methylpent-4-en-2-yn-1-ols and 6-hydroxy-2,3-dihydro-6H-pyran-3-ones are condensed in different ways to a series of tricyclic dioxadienones which contain the basic framework of the cadlinolides A mechanism of the intramolecular enyne-ene cycloisomerization and the origin of the resulting type I and type II dienes is proposed.
- Hoffmann, H. M. R.,Krumwiede, D.,Mucha, B.,Oehlerking, H. H.,Prahst, G. W.
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p. 8999 - 9018
(2007/10/02)
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- Ylidenebutenolide Mycotoxins. Concise Syntheses of Patulin and Neopatulin from Carbohydrate Precursors
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Conversion of arabinose 10 to the protected ketone 13 followed by Wittig condensation to 14, acidcatalysed cyclisation (to lactone 16), dehydration and deprotection provides a brief synthesis of the mycotoxic substance patulin 1, which is produced by Penicillium and Aspergillus spp.In a similar manner, the biogenetic precursor to patulin, neopatulin 8, is synthesized from lyxose 25 via the key intermediates 24, 28 and 30.
- Bennett, Mandy,Gill, G. Byron,Pattenden, Gerald,Shuker, Anthony J.,Stapleton, Alan
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p. 929 - 937
(2007/10/02)
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- Total synthesis of 4-(D-alanylamino)-2-amino-2,3,4-trideoxy-DL-threo-pentose (3-deoxy-DL-prumycin)
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3-Deoxy-DL-prumycin (1) was synthesized from 2-furanmethanol (2-furfuryl alcohol, 2) in eleven steps in 15% total yield. Michael addition of azide anion to 2,3-dideoxy-DL-pent-2-enopyranos-4-ulose (3) and reduction in situ of the adduct afforded the key i
- Constantinou-Kokotou,Couladouros,Georgiadis,Kokotos,Georgiadis
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p. 163 - 172
(2007/10/02)
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- PREPARATION OF 6-HYDROXY-2H-PYRAN-3(6H)-ONE FROM 2-FURYLCARBINOL BY PHOTOOXIDATION. SYNTHESIS OF A PHEROMONE OF VESPA ORIENTALIS
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Photooxidation of 2-furylcarbinols followed by reduction with triphenylphosphine afforded 6-hydroxy-2H-pyran-3(6H)-ones in excellent yield.The method was applied to synthesis of 6-undecyltetrahydro-2-pyrone, a pheromone of Vespa orientalis.
- Kuo, Yueh-Hsiung,Shih, Kae-Shyang
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p. 1941 - 1949
(2007/10/02)
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