- Synthesis of L-ascorbic acid derivatives as potential bone remodeling agents taking advantage of the Mitsunobu reaction
-
The synthesis of ascorbic acid derivatives 7a-d is described. Starting from alkenylacetates 1a-d subjected to a hydrosilylation reaction, the resulting hydroxy chloro silanes 3a-d were obtained in high yield. The latter compounds were reacted with potassium phthalimide followed with hydrazine hydrate to give the amino silanols 5a-d. Ascorbic acid was then alkylated on its 3-hydroxy position to give 7a-d by means of a Mitsunobu reaction.
- Vila?a, Gil,Rubio, Cyril,Susperregui, Jacques,Latxague, Laurent,Déléris, Gérard
-
-
Read Online
- Synthesis of 3-sila derivatives of L-ascorbic acid via Mitsunobu reaction
-
Various 3-sila derivatives of L-ascorbic acid were synthesized in satisfactory yields. The ether link was formed by an unusual aspect of the Mitsunobu reaction, without the need of protecting the remaining hydroxy groups.
- Rubio, Cyril,Susperregui, Jacques,Latxague, Laurent,Déléris, Gérard
-
-
Read Online
- Tetrahydro-4 H-pyran-4-one: From the Laboratory Scale to Pilot Plant Manufacture
-
This study describes our recent efforts to find an efficient and scalable route to tetrahydro-4H-pyran-4-one using the commercially available starting materials. The route scouting work and the full development of an efficient access to the target are described. This work culminated in the preparation of above 20 kg of the title compound in our pilot plant facility.
- Zahim, Sara,Delacroix, Kenny,Carlier, Agathe,Berranger, Thierry,Bergraser, Julie,Echeverria, Pierre-Georges,Petit, Laurent
-
p. 199 - 206
(2022/01/12)
-
- Developing a Bench-Scale Green Diboration Reaction toward Industrial Application
-
We report a new methodology for the organocatalytic diboration reaction using inexpensive, sustainable, nontoxic, commercially available halogen salts. This is an educative manuscript for the transformation of laboratory scale reactions into a sustainable approach of appeal to industry.
- Farre, Albert,Briggs, Rachel,Pubill-Ulldemolins, Cristina,Bonet, Amadeu
-
supporting information
p. 4775 - 4782
(2017/10/27)
-
- Amine Catalysis for the Organocatalytic Diboration of Challenging Alkenes
-
The generation of in situ sp2–sp3diboron adducts has revolutionised the synthesis of organoboranes. Organocatalytic diboration reactions have represented a milestone in terms of unpredictable reactivity of these adducts. However, current methodologies have limitations in terms of substrate scope, selectivity and functional group tolerance. Here a new methodology based on the use of simple amines as catalyst is reported. This methodology provides a completely selective transformation overcoming current substrate scope and functional/protecting group limitations. Mechanistic studies have been included in this report.
- Farre, Albert,Soares, Kaline,Briggs, Rachel A.,Balanta, Angelica,Benoit, David M.,Bonet, Amadeu
-
supporting information
p. 17552 - 17556
(2016/11/28)
-
- Iron-Catalyzed Cross-Coupling of Alkenyl Acetates
-
Stable C-O linkages are generally unreactive in cross-coupling reactions which mostly employ more electrophilic halides or activated esters (triflates, tosylates). Acetates are cheap and easily accessible electrophiles but have not been used in cross-couplings because the strong C-O bond and high propensity to engage in unwanted acetylation and deprotonation. Reported herein is a selective iron-catalyzed cross-coupling of diverse alkenyl acetates, and it operates under mild reaction conditions (0 C, 2 h) with a ligand-free catalyst (1-2 mol%). Iron clad: Acetates are underutilized electrophiles in metal-catalyzed cross-coupling reactions because of the strong alkenyl C-O bond and their propensity to engage in unwanted reactions. Combination of a ligand-free low-valent Fe catalyst with nucleophilic organomagnesium reagents, low temperature, and short reaction times results in highly selective cross-couplings with alkenyl acetates.
- G?rtner, Dominik,Stein, André Luiz,Grupe, Sabine,Arp, Johannes,Von Wangelin, Axel Jacobi
-
supporting information
p. 10545 - 10549
(2015/09/02)
-
- Enantioselective Hydroformylation of 1-Alkenes with Commercial Ph-BPE Ligand
-
A rhodium complex, in conjunction with commercially available Ph-BPE ligand, catalyzes the branch-selective asymmetric hydroformylation of 1-alkenes and rapidly generates α-chiral aldehydes. A wide range of terminal olefins including 1-dodecene were examined, and all delivered high enantioselectivity (up to 98:2 er) as well as good branch:linear ratios (up to 15:1). (Chemical Equation Presented).
- Yu, Zhiyong,Eno, Meredith S.,Annis, Alexandra H.,Morken, James P.
-
supporting information
p. 3264 - 3267
(2015/07/15)
-
- Synthesis and glycosidase inhibition studies of 5-methyl-substituted tetrahydroxyindolizidines and -pyrrolizidines related to natural hyacinthacines B
-
The synthesis of three tetrahydroxyindolizidines and one tetrahydroxypyrrolizidine related to natural hyacinthacines B and their biological evaluation as glycosidase inhibitors is reported. The target molecules were obtained through highly stereoselective cycloadditions between sugriched allylic and homoallylic alcohols. This allowed the installation of a methyl group at C5 - a common feature of many natural hyacinthacines - with high control over the stereoselectivity. The new compounds inhibit amyloglucosidase from Aspergillus niger and β-glucosidase from almonds. Compound 1 is a competitive inhibitor of amyloglucosidase and shows a fair selectivity towards this enzyme. The presence of C5-Me substitution in indolizidines 2 and 3 slightly diminishes the inhibitory activity towards amyloglucosidase whereas it improves the inhibitory properties towards β-glucosidase. Cycloaddition between a carbohydrate-derived nitrone and suitable chemoenzymatically prepared enantioenriched allylic and homoallylic alcohols allowed the straightforward synthesis of three tetrahydroxyindolizidines and one tetrahydroxypyrrolizidine related to natural hyacinthacines B. They inhibit amyloglucosidase from Aspergillus niger and β-glucosidase from almonds. Copyright
- Martella, Daniele,Cardona, Francesca,Parmeggiani, Camilla,Franco, Francisco,Tamayo, Juan A.,Robina, Inmaculada,Moreno-Clavijo, Elena,Moreno-Vargas, Antonio J.,Goti, Andrea
-
supporting information
p. 4047 - 4056
(2013/07/19)
-
- Hydroacetoxylation of olefins with acetic acid genetated in situ from vinyl acetate in the presence of ruthenium complexes
-
Ruthenium complexes catalyze the decomposition of vinyl acetate releasing the acetic acid and its subsequent addition to linear and cyclic olefins.
- Khusnutdinov,Shchadneva,Khisamova,Dzhemilev
-
experimental part
p. 155 - 160
(2011/05/03)
-
- Esterification of carboxylate-based ionic liquids with alkyl halides
-
A facile reaction of 1-ethyl-3-methylimidazolium acetate ([EMIm]Ac) with dichloromethane at room temperature was observed with esters among the products. This esterification can be exploited for mild solvent-free esterification with a range of other carboxylate-based ionic liquids and alkyl halides. The Royal Society of Chemistry.
- Zhao, Bin,Greiner, Lasse,Leitner, Walter
-
scheme or table
p. 2973 - 2975
(2011/04/24)
-
- Ruthenium(III) acetylacetonate [Ru(acac)3] -An efficient recyclable catalyst for the acetylation of phenols, alcohols, and amines under neat conditions
-
A catalytic amount of ruthenium(III) acetylacetonate (2 mol%) [Ru(acac)3] enables solvent-free acetylation of phenols, alcohols, and amines at ambient temperature in good to excellent yields. Furthermore, the catalyst could be recovered and reused at least three times without a significant loss in yields.
- Varala, Ravi,Nasreen, Aayesha,Adapa, Srinivas R.
-
p. 148 - 152
(2008/02/11)
-
- Construction of tetrahydrofurans by PdII/PdIV- catalyzed aminooxygenation of alkenes
-
(Chemical Equation Presented) Resolute in the face of elimination: Substituted 3-aminotetrahydrofurans were prepared in good yield and with modest to high diastereoselectivity by the Pd-catalyzed reaction shown in the scheme (Phth = phthaloyl). Mechanisti
- Desai, Lopa V.,Sanford, Melanie S.
-
p. 5737 - 5740
(2008/04/12)
-
- Catalytic enantioselective alkylations of tetrasubstituted olefins. Synthesis of all-carbon quaternary stereogenic centers through Cu-catalyzed asymmetric conjugate additions of alkylzinc reagents to enones
-
A method for Cu-catalyzed asymmetric conjugate addition (ACA) of dialkylzinc reagents to tetrasubstituted five- and six-membered cyclic enones that afford quaternary all-carbon stereogenic centers in up to 95% ee is reported. Catalytic ACAs are practical
- Hird, Alexander W.,Hoveyda, Amir H.
-
p. 14988 - 14989
(2007/10/03)
-
- Catalytic enantioselective synthesis of quaternary all-carbon stereogenic centers. Preparation of α,α′-disubstituted β,γ-unsaturated esters through Cu-catalyzed asymmetric allylic alkylations
-
(Chemical Equation Presented) Peptide-based chiral ligands, readily prepared from commercially available materials, are used to promote Cu-catalyzed asymmetric allylic alkylations of α,β-unsaturated esters bearing a γ-phosphate with various alkylzinc reagents. These transformations lead to the formation of α,α′-dialkyl-β,γ-unsaturated esters in high yields as well as high regio- (re) and enantloselectivities (ee).
- Murphy, Kerry E.,Hoveyda, Amir H.
-
p. 1255 - 1258
(2007/10/03)
-
- Chemokine receptor binding heterocyclic compounds with enhanced efficacy
-
The invention relates to heterocyclic compounds consisting of a core nitrogen atom surrounded by three pendant groups, wherein two of the three pendant groups are preferably benzimidazolyl methyl and tetrahydroquinolyl, and the third pendant group contains N and optionally contains additional rings. The compounds bind to chemokine receptors, including CXCR4 and CCR5, and demonstrate protective effects against infection of target cells by a human immunodeficiency virus (HIV).
- -
-
-
- Chemokine receptor binding heterocyclic compounds with enhanced efficacy
-
The invention relates to heterocyclic compounds consisting of a core nitrogen atom surrounded by three pendant groups, wherein two of the three pendant groups are preferably benzimidazolyl methyl and tetrahydroquinolyl, and the third pendant group contains N and optionally contains additional rings. The compounds bind to chemokine receptors, including CXCR4 and CCR5, and demonstrate protective effects against infection of target cells by a human immunodeficiency virus (HIV).
- -
-
Page/Page column 46-48
(2010/02/03)
-
- The First Synthesis of a 10-Membered Ring by Olefin Metathesis: Jasmine Ketolactone
-
An unprecedentedly short route to jasmine ketolactone (Z)-2 and its E-isomer is described, which is based on the efficient formation of the 10-membered ring via ring closing olefin metathesis (RCM) of diene 8. The latter is conveniently prepared by a three component coupling reaction consisting of the 1,4-addition of the lithium enolate of 3-butenyl (diphenylmethylsilyl)acetate 6 to 2-cyclopentenone and subsequent trapping of the enolate thus formed with allyl iodide.
- Fürstner, Alois,Müller, Thomas
-
p. 1010 - 1012
(2007/10/03)
-
- Cobalt(II) Chloride Catalyzed Acylation of Alcohols with Acetic Anhydride: Scope and Mechanism
-
Cobalt(II) chloride catalyzes the acetylation of a variety of alcohols with acetic anhydride in excellent yield.Primary hydroxyl groups can be selectively acylated in the presence of secondary and tertiary ones while the secondary hydroxyl groups can be preferentially acetylated in the presence of tertiary ones.Tertiary alcohols have been found to give ketones, acetoacetates, olefins, and diketene in addition to the acetate.The β-hydroxy esters and ketones can be acylated under these conditions without any elimination, and this reaction has been compared with 4-(dimethylamino)pyridine (DMAP)-mediated acylations where elimination of the resulting β-acetoxy carbonyl compound is observed.A detailed investigation of the acylation of tertiary alcohols has revealed that these reactions proceed via a tertiary alkoxy radical and ketene.A mechanism for these acylations is proposed by invoking an electron-transfer process.
- Iqbal, Javed,Srivastava, Rajiv Ranjan
-
p. 2001 - 2007
(2007/10/02)
-
- Regioselective Synthesis of Hydroxy Sulphides via Trifluoroacetoxysulphenylation of Derivatives of Allylic Alcohols
-
Reaction of manganese(III) acetate with diphenyl disulphide in dichloromethane-trifluoroacetic acid in the presence of allylic esters gives trifluoroacetoxy sulphides, which on hydrolysis readily afford vicinal hydroxy sulphides.With acetate esters, neighbouring group participation by the acetate functionality controls the reaction course.Thus regiospecific addition to allyl acetate affords after hydrolysis only 3-phenylthiopropane-1,2-diol.In contrast, with trifluoroacetate esters the inductive effects of the trifluoroacetate functionality lead to a different regiocontrol.Thus addition of diphenyl disulphide to allyl trifluoroacetate gives after hydrolysis only 2-phenylthiopropane-1,3-diol.The regio- and stereochemistry of addition to a variety of other allylic (and homoallylic) esters is described and the extension of this type of regiocontrol is discussed.
- Samii, Zakaria K. M. Abd El,Ashmawy, Mohamed I. Al,Mellor, John M.
-
p. 2509 - 2516
(2007/10/02)
-
- Preparation of 1-Alkenes by the Palladium-Catalyzed Hydrogenolysis of Terminal Allylic Carbonates and Acetates with Formic Acid-Triethylamine
-
A useful method for the preparation of 1-alkenes from terminal allylic carbonates and acetates by the palladium-catalyzed reaction with formates is described.Formic acid-triethylamine is a suitable reductant.As catalyst, Pd2(dba)3CHCl3-P(n-Bu)3 gave the best result, 0.05-0.2 molpercent being sufficient (turnover 500-2000).Using this method, various 1-alkenes were prepared in good yields with high selectivity.
- Tsuji, Jiro,Minami, Ichiro,Shimizu, Isao
-
p. 623 - 627
(2007/10/02)
-
- REGIOSELECIVE HYDROXYSULPHENYLATION OF DERIVATIVES OF ALLYLIC ALCOHOLS AND AMINES
-
Reaction of manganic acetate with diphenyldisulphide in dichloromethane-trifluoroacetic acid in the presence of allylic esters or amides of allylamine gives trifluoroacetoxysulphides and hence by ready hydrolysis vicinal hydroxysulphides.The regiochemical outcome can be controlled by selection of either an acetyl- or trifluoroacetyl derivative.
- Samii, Zakaria K M Abd El,Ashmawy, Mohamed I Al,Mellor, John M
-
p. 5289 - 5292
(2007/10/02)
-
- ON THE POSSIBILITY OF DIOXIRANE FORMATION FROM CRIEGEE PEROXIDE ADDUCTS
-
The possibility of dioxirane formation from thermal and cesium fluoride induced decomposition of α-t-butyldimethylsilyloxyalkyl peroxybenzoates has been examined.
- Saito, Isao,Nagata, Ryu,Matsuura, Teruo
-
p. 2687 - 2690
(2007/10/02)
-
- Nitrosamine Photolysis as a Synthetic Method: The Addition of Aminium Radicals to Unsaturated Carbon-Carbon Bonds
-
Acid complexed nitrosamines decompose from their lowest singlet excited state to gine aminium radicals and nitric oxide radical transients.Aminium radicals initiate addition of various unsaturated groups to give 1-amino-2-nitroso compounds under an inert atmosphere, or 1-amino-2-nitrates under oxygen.In this report, photoaddition of nitroamines to olefins, acetylenes and fused aromatic hydrocarbons, and the subsequent transformations of the intermediates are described.Aminium radical initiated intramolecular cyclization to prepare tetracyclic aza compounds is also described.While photoaddition of nitrosamines to 4-propenylanisole or 3-butenol wes efficient, that to 3-butenyl benzoates under oxidative conditions was only fair, obviously due to the presence of a benzene ring.The oxidative photoaddition to 3-butenyl halide was followed by spontaneous cyclization to an azaspiro compound.The photoaddition to phenyl-substituted acetylenes gave β-nitroso enamines which hydrolyzed to diketomonoximes under neitral conditions but decomposed extensively under acidic conditions.Certain fused aromatic hydrocarbons acted as singlet sensitizers as well as substrates to induce similar addition giving amino nitroso adducts.These adducts took different courses of conversion dependent on reaction conditions, and on steric and electronic factors.
- Chow, Yuan L.,Colon, Carlos J.,Chang, Dawid W. L.,Pillay, K. Somasekharen,Lochart Robert D.,Tezuka, Takahiro
-
p. 622 - 634
(2007/10/02)
-
- PARTICIPATION IN THE FORMATION OF IODO UREAS FROM 3-BUTEN-1-OL DERIVATIVES. A REINVESTIGATION.
-
Treatment of O-substitued derivatives of 3-buten-1-ol with silver cyanate and iodine, followed by ammonia, gave cyclic derivatives 5 and 6.These compounds were previously assigned the linear structures 3 and 4, respectively.Evidence in support of the proposed structural reassignment was obtained form high-field 1H and 13C NMR studies.Both 5 and 6 undergo loss of the ureido group upon treatment with water to give 9 and 10, and 12, respectively.Potential mechanism for the observed reactions are discussed.
- Kohn, H.,Bean, M. B.,Rohrscheidt, C. von,Willcott, M. R.,Warnhoff, E. W.
-
p. 3195 - 3201
(2007/10/02)
-
- Solvomercuration-Demercuration. 8. Oxymercuration-Demercuration of Methoxy-, Hydroxy-, and Acetoxy-Substituted Alkenes
-
The oxymercuration-demercuration (OM-DM) of a series of methoxy-, hydroxy-, and acetoxy-substituted alkenes was examined.The systems examined were the allyl, crotyl, 3-buten-1-yl, 4-penten-1-yl, and 5-hexen-1-yl.The methoxyalkenes undergo hydration with very high regioselectivity and almost quantitative yield in all cases.However, a small -I effect is observed in the case of the allylalkene (97.1percent Markovnikov vs. 99.5percent in 1-hexene).Moreover, in the crotyl case, a major directing effect is observed: 97.7percent 3-ol, 2.3percent 2-ol.The other three alkenes undergo the OM reaction with no effect from the methoxy group (99.5percent Markovnikov isomer).In contrast, only allyl-, crotyl-, and 3-buten-1-yl alcohols produce major amounts of hydrated products, the diols.While no hydroxyl group directing effect is observed in the allyl system, a major one is again seen in the case of the crotyl: 93.5percent l,3-diol and 6.5percent l,2-diol.The major products from the 4-penten-1-yl and 5-hexen-1-yl and alcohols are 2-methyltetrahydrofuran and 2-methyltetrahydropyran, respectively, resulting from OH-5 and OH-6 neighboring group participation in the OM stage.The acetoxy alkenes undergo hydration to give diols in ca. 80percent yield with ca. 20percent unreacted starting material.This is the result of a competitive deoxymercuration reaction which is occurring in the DM stage.However, the yield of hydrated products can be increased by varying the amount of base used in the DM.Neighboring-group participation, AcO-5, is observed in the allyl system only, resulting in a 65percent yield of the Markovnikov oxymercurial, by 1H NMR analysis, and a 35percent yield of the acetoxy-exchanged mercurial.Again, a major -I-directing effect of the acetoxy group was observed in the crotyl system but not in the others.In addition to the expected l,2- and l,3-diols, the OM-DM of crotyl acetate also resulted in small amounts of the unexpected 2,3-diol under kinetic conditions.Finally, a modified DM procedure has been developed which is compatible with the acetoxy group.
- Brown, Herbert C.,Lynch, Gary J.
-
p. 531 - 538
(2007/10/02)
-
- METATHESE D'ACETATES D'ALCOOLS ω-INSATURES. SYNTHESE DE PHEROMONES D'INSECTES
-
Esters of alkenoic acids, including insect pheromones as examples, have been synthesized using alkene metathesis reactions.
- Levisalles, Jaques,Villemin, Didier
-
p. 3181 - 3186
(2007/10/02)
-
- Process for the production of unsaturated esters
-
The thermal reaction of olefinic reactants with formaldehyde in saturated esters as solvent provides a convenient one-step preparation of unsaturated esters. The unsaturated ester products can be pyrolyzed to isoprene or used as chemical intermediates and in flavors and fragrances.
- -
-
-