- Rh(I)-Catalyzed Decarboxylative Arylation of Alkynyl Cyclic Carbonates: Divergent Access to Substituted α-Allenols and 1,3-Butadienes
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Rh(I)-catalyzed decarboxylative arylation of alkynyl cyclic carbonates using commercially available and low-toxic aryl boronic acids has been disclosed. Depending on the nature of the cyclic carbonates, the methodology provides a straightforward platform to access either substituted 2,3-allenols or 1,3-butadiene derivatives. Internal alkynyl cyclic carbonates undergo monoarylation to conveniently afford 2,3-allenols with high syn-selectivity for the aryl and hydroxy groups. Whereas, terminal alkynyl carbonates led to the formation of diarylated 1,3-butadiene derivatives having cis-configuration for the two aryl groups via allenyl rhodium(I)alkoxide intermediate. The compatibility of various functional groups allowed to develop a library of diversely functionalized scaffolds with excellent regioselectivity in good yields. Late-stage transformation of a series of natural products highlights the wide applicability of the arylation process. Additionally, scale-up experiments and downstream transformations of α-allenol derivatives into other valuable heterocycles illustrate the efficacy of the protocol.
- Sontakke, Geetanjali S.,Shukla, Rahul K.,Volla, Chandra M. R.
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supporting information
p. 565 - 573
(2021/11/16)
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- C-Quaternary alkynyl glycinols via the Ritter reaction of cobalt complexed alkynyl glycols
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A novel approach to C-quaternary alkynyl glycinols based on the Ritter reaction of acetonitrile with cobalt complexed alkynyl glycols is presented. The reaction is promoted by acids such as H2SO4 or BF3·Et2O to give oxazolines as the reaction products. These are subjected to cobalt complex cleavage in oxidative conditions and subsequent acidic hydrolysis providing amino alcohols. The substrates for the Ritter reaction can be easily assembled to introduce structural diversity at both variable positions. The Ritter reaction conditions for oxazoline formation is compatible with a range of substituents at the alkyne terminal position providing oxazolines in moderate to good yields. Methyl, hydroxymethyl and silyloxymethyl substituents at the reaction center of glycols are well tolerated, while a phenyl group in this position is detrimental to the reaction. s
- Grammatoglou,Bolsakova,Jirgensons
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p. 27530 - 27537
(2017/07/10)
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- Poly(ethylene glycol) as a reaction matrix in platinum- or gold-catalyzed cycloisomerization: A mechanistic investigation
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Design for diversity: A new catalytic system based on PEG-3400 and a metal salt (Pt or Au) was designed to efficiently perform a cycloisomerization reaction under microwave irradiation, which gave diverse heterocycles in good to excellent yields, after a
- Spina, Rosella,Colacino, Evelina,Martinez, Jean,Lamaty, Frédéric
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supporting information
p. 3817 - 3821
(2013/04/24)
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- Synthesis of furan-3-carboxylic and 4-methylene-4,5-dihydrofuran-3- carboxylic esters by direct palladium iodide catalyzed oxidative carbonylation of 3-yne-1,2-diol derivatives
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A variety of 3-yne-1,2-diol derivatives 1, bearing a primary or secondary alcoholic group at C-1, have been efficiently converted into high value added furan-3-carboxylic esters 2 in one step by PdI2/KI-catalyzed direct oxidative carbonylation, carried out in alcoholic media under relatively mild conditions (100 °C under 40 atm of a 4/1 mixture of CO and air). Carbonylated furans 2 were obtained in fair to excellent isolated yields (56-93%) through a sequential 5-endo-dig heterocyclization-alkoxycarbonylation- dehydration process, using only oxygen as the external oxidant. Under similar conditions, 2-methyl-3-yne-1,2-diols 3, bearing a tertiary alcoholic group, afforded 4-methylene-4,5-dihydrofuran-3-carboxylates 4 in satisfactory yields (58-70%).
- Gabriele, Bartolo,Mancuso, Raffaella,Maltese, Vito,Veltri, Lucia,Salerno, Giuseppe
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p. 8657 - 8668
(2012/11/07)
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- A simple and convenient synthesis of substituted furans and pyrroles by CuCl2-catalyzed heterocyclodehydration of 3-yne-1,2-diols and N-Boc- or N-tosyl-1-amino-3-yn-2-ols
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A simple and economical synthesis of substituted furans and pyrroles, by ligand-free CuCl2-catalyzed heterocyclodehydration of readily available 3-yne-1,2-diols and N-Boc- or N-tosyl-1-amino-3-yn-2-ols, respectively, is presented. Reactions are carried out in MeOH at 80-100 °C for 1-24 h and afford the corresponding heterocyclic derivatives in 53-99% isolated yields.
- Gabriele, Bartolo,Plastina, Pierluigi,Vetere, Mabel V.,Veltri, Lucia,Mancuso, Raffaella,Salerno, Giuseppe
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experimental part
p. 3565 - 3567
(2010/08/07)
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