- Sustainable Palladium-Catalyzed Tsuji-Trost Reactions Enabled by Aqueous Micellar Catalysis
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Palladium-catalyzed allylic substitution, or "Tsuji-Trost"reactions, can be run under micellar catalysis conditions featuring not only chemistry in water but also numerous combinations of reaction partners that require low levels of palladium, typically on the order of 1000 ppm (0.1 mol %). These couplings are further characterized by especially mild conditions, leading to a number of cases not previously reported in an aqueous micellar medium. Inclusion of diverse nucleophiles, such as N-H heterocycles, alcohols, dicarbonyl compounds, and sulfonamides is described. Intramolecular cyclizations further illustrate the broad utility of this process. In addition to recycling studies, a multigram scale example is reported, indicative of the prospects for scale up.
- Braga, Felipe C.,Gallou, Fabrice,Lee, Nicholas R.,Lippincott, Daniel J.,Lipshutz, Bruce H.,Moghadam, Farbod A.,Zhu, Bingchun
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supporting information
(2020/07/15)
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- Tandem Z-Selective Cross-Metathesis/Dihydroxylation: Synthesis of anti-1,2-Diols
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Abstract: A stereoselective synthesis of anti-1,2-diols has been developed using a multitasking Ru catalyst in an assisted tandem catalysis protocol. A cyclometalated Ru complex catalyzes first a Z-selective cross-metathesis of two terminal olefins, followed by a stereospecific dihydroxylation. Both steps are catalyzed by Ru, as the Ru complex is converted to a dihydroxylation catalyst upon addition of NaIO4. A variety of olefins were transformed into valuable, highly functionalized, and stereodefined molecules. Mechanistic experiments were performed to probe the nature of the oxidation step and catalyst inhibition pathways. These experiments point the way to more broadly applicable tandem catalytic transformations. Two steps with one cat.: 1,2-anti-Diols are accessible through a tandem Z-selective cross-metathesis/dihydroxylation using an assisted tandem catalysis protocol. Both steps are catalyzed by the Ru complex, and the stereocontrol of the cross-metathesis is translated through high stereospecificity in the dihydroxylation step to diastereoselectivity for the 1,2-anti-diol.
- Dornan, Peter K.,Wickens, Zachary K.,Grubbs, Robert H.
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supporting information
p. 7134 - 7138
(2015/06/16)
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- Access to oxetane-containing psico-nucleosides from 2-methyleneoxetanes: A role for neighboring group participation?
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The first psico-oxetanocin analogue of the powerful antiviral natural product, oxetanocin A, has been readily synthesized from cis-2-butene-1,4-diol. Key 2-methyleneoxetane precursors were derived from β-lactones prepared by the carbonylation of epoxides. F+-mediated nucleobase incorporation provided the corresponding nucleosides in good yield but with low diastereoselectivity. Surprisingly, attempted exploitation of anchimeric assistance to increase the selectivity was not fruitful. A range of 2-methyleneoxetane and related 2-methylenetetrahydrofuran substrates was prepared to explore the basis for this. With one exception, these substrates also showed little stereoselectivity in nucleobase incorporation. Computational studies were undertaken to examine if neighboring group participation involving fused [4.2.0] or [4.3.0] intermediates is favorable (Figure presented).
- Liang, Yanke,Hnatiuk, Nathan,Rowley, John M.,Whiting, Bryan T.,Coates, Geoffrey W.,Rablen, Paul R.,Morton, Martha,Howell, Amy R.
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experimental part
p. 9962 - 9974
(2012/02/05)
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- A selective Ru-catalyzed semireduction of alkynes to Z olefins under transfer-hydrogenation conditions
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By using a readily available, air- and moisture-stable dihydrido-Ru complex, a variety of Z olefins are accessible under transfer-hydrogenation conditions with formic acid as the hydrogen source in excellent yields and Z/E selectivities. A discerning transformation: Z-Configured C=C bonds are stereoselectively formed from alkynes in the presence of a Ru catalyst with formic acid as the sole H2 source at room temperature (see scheme). A variety of functional groups are compatible with this novel procedure. Operational simplicity and the lack of overreduction products are characteristics for this unprecedented process.
- Belger, Christian,Neisius, N. Matthias,Plietker, Bernd
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supporting information; experimental part
p. 12214 - 12220
(2011/03/17)
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- Synthesis of spiro C-arylglycoriboside via Pd(II)-catalyzed spirocyclization
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Spiro C-arylglycoriboside was synthesized in 21 steps via Pd(II)-catalyzed spirocyclization as a key reaction. Hemiketal was obtained in 47% overall yield from cis-2-butene-1,4-diol and spirocyclized with PdCl2(PhCN) 2 in dilute THF solution (0.01 M) to afford the 1,6-dioxaspiro[4.4] nonane skeleton in high yield. The spirocyclo adduct was transformed into spiro C-arylglycoriboside in five steps. Georg Thieme Verlag Stuttgart New York.
- Awasaguchi, Ken-Ichiro,Miyazawa, Masahiro,Uoya, Ikuyo,Inoue, Koichi,Nakamura, Koji,Yokoyama, Hajime,Kakuda, Hiroko,Hirai, Yoshiro
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scheme or table
p. 2392 - 2396
(2010/12/18)
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- A novel pentose synthesis via palladium(II)-catalyzed cyclization of an unstable hemiacetal
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PdCl2(PhCN)2 (5 mol%)-catalyzed cyclization of a hemiacetal derived from (E,2S,3R)-2,3-isopropylidenedioxy-6-(tetrahydro-2H- pyran-2-yl)-4-hexenal and methanol gave substituted furanoside in moderate yield, exclusively via 5-exo-mode cyclization, without the need for a reoxidant. New stereogenic centers at C1 and C4 on the tetrahydrofuran ring showed preferential 1R and 4R stereochemistry due to anomeric effect (n oσ*c-o) and A1,2 strain, respectively. This methodology was applied to stereocontrolled synthesis of pentoses: D-ribose and L-lyxose. The Japan Institute of Heterocyclic Chemistry.
- Awasaguchi, Ken-Ichiro,Miyazawa, Masahiro,Uoya, Ikuyo,Inoue, Koichi,Nakamura, Koji,Yokoyama, Hajime,Hirai, Yoshiro
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experimental part
p. 2105 - 2121
(2011/04/24)
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- Synthesis of homoallylic alcohols via lewis acid assisted enantioselective desymmetrization
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A highly enantioselective allylic substitution of (Z)-but-2-ene-1,4-diol derivatives was developed using a rhodium(I) catalyst and arylboronic acids as nucleophiles. The reaction yields versatile homoallylic alcohols from readily available linear biscarbonates. Georg Thieme Verlag Stuttgart.
- Yu, Bing,Menard, Frederic,Isono, Naohiro,Lautens, Mark
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experimental part
p. 853 - 859
(2009/08/16)
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- Zinc oxide (ZnO) as a new, highly efficient, and reusable catalyst for acylation of alcohols, phenols and amines under solvent free conditions
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Zinc oxide (ZnO) is a highly efficient catalyst for the acylation of a variety of alcohols, phenols and amines with acid chlorides or acid anhydrides under solvent free conditions. Primary, secondary, tertiary, allylic and benzylic alcohols, diols and phenols with electron donating or withdrawing substituents can be easily acylated in good to excellent yield.
- Hosseini Sarvari, Mona,Sharghi, Hashem
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p. 10903 - 10907
(2007/10/03)
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- Lipase-catalyzed monoprotection of 1,4-diols in an organic solvent using vinyl benzoate as acyl transfer agent
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Lipase from Mucor miehei (MML) has been selected as the most suitable enzyme to catalyze the efficient monobenzoylation of 1,4-diols using vinyl benzoate as acyl transfer reagent in tert-butyl methyl ether. The regioselectivity of the monobenzoylation of
- Ciuffreda, Pierangela,Casati, Silvana,Santaniello, Enzo
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p. 3663 - 3665
(2007/10/03)
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- A novel method for the synthesis of 4'-thiopyrimidine nucleosides using hypervalent iodine compounds.
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The coupling reactions of cyclic sulfides with a silylated pyrimidine nucleobase using a hypervalent iodine reagent were investigated. The reaction of silylated uracil with cyclic sulfide 12 using PhI=O gave the desired beta-anomer 14 in moderate yield. 4
- Nishizono, Naozumi,Baba, Ryosuke,Nakamura, Chika,Oda, Kazuaki,Machida, Minoru
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p. 3692 - 3697
(2007/10/03)
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- Synthesis and properties of glycolaldehyde di- and triphosphate
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Use of photolabile acetal protecting groups enables the synthesis of glycolaldehyde di- and triphosphate 4 and 5, which undergo enolisation at significantly lower pH values than glycolaldehyde phosphate 1. At pH > 10, 5 is converted to 1 and inorganic pyrophosphate.
- Lawrence,Sutherland
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p. 170 - 172
(2007/10/03)
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- Nucleosides and nucleotides. 189. Investigation of the stereoselective coupling of thymine with meso-thiolane-3,4-diol-1-oxide derivatives via the Pummerer reaction
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We investigated the stereoselective coupling of thymine with sulfoxides derived from mesothiolane-3,4-diol via the Puremeter reaction. The introduction of 2,4-dimethoxybenzoyl groups to the hydroxyl groups of meso- thiolane-3,4-diol-1-oxide was effective
- Naka, Takashi,Nishizono, Naozumi,Minakawa, Noriaki,Matsuda, Akira
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p. 6297 - 6300
(2007/10/03)
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- Stereoselective total synthesis of the pseudopterolide kallolide A
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A total synthesis of the pseudopterolides, kallolide A (36) and kallolide A acetate (35), has been achieved. The racemic forms were prepared from the syn adduct 20 of furan 13 and stannane 17 (BF3·OEt2-promoted addition) via the 15-membered propargylic allylic ether 25. [2,3]Wittig ring contraction led to the cis, anti, cis product 26. Alcohol 26 was transformed to butenolide 34 with net retention of configuration by Pd(PPh3)4- catalyzed carbonylation of the mesylate 27 and ensuing AgNO3-catalyzed cyclization of the derived allenic acid 29. Solvolysis of the SEM ether (at C2) 34 in acetic acid or aqueous t-BuOH afforded racemic kallolide A acetate (35) and kallolide A (36), respectively, with inversion of stereochemistry by an S(N)1 process. Key elements of stereocontrol, including the steric outcome of the [2,3]Wittig ring contraction, the allenic ester isomerization, and the solvolysis reactions, were predicted from molecular mechanics calculations. The C8 and C2 epimers 45 and 46 of the cis, anti, cis kallolide A SEM ether precursor 34 were also prepared. The synthetic route originated from the anti adduct 19 of aldehyde 13 and the allylic chloride 16 and CuCl (cat), HSiCl3, and i-Pr2NEt. Adduct 19 was subjected to the same sequence as the syn counterpart 20 to produce the trans, anti, cis[2,3]Wittig ring contraction product 42. The derived alleonate 44 afforded a 1:1 mixture of butenolides 45 and 46 upon sequential treatment with TBAF and AgNO3. Finally, the natural enantiomer (+)-36 of kallolide A was synthesized from the enantioenriched syn adduct (+)-20, prepared by addition of allylic stannane 17 to aldehyde 13 promoted by a modified chiral acyloxyborane Lewis acid.
- Marshall, James A.,Liao, Junkai
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p. 5962 - 5970
(2007/10/03)
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- Photodecarbonylation of chiral cyclobutanones
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Triplet photosensitized irradiation of 2(S),3(R)-bis[(benzoyloxy)methyl]cyclobutanone gave optically pure (-)E-1(S),2(S)-bis(benzoyloxymethyl)cyclopropaneas a major product in the nonpolar fraction along with its stereoisomer and cycloelimination products. The absolute stereochemistry of the chiral cyclopropane was established by independent synthesis and X-ray crystal structure determination of a synthetic precursor. The distribution of decarbonylation and cycloelimination products was inversely dependent on the concentration of the substrate. Irradiation of the same ketone in tetrahydrofuran or benzene gave mostly cycloelimination products. Addition of Michler's ketone increased the ratio of photodecarbonylation, suggesting a triplet state pathway for this process. This was corroborated by the addition of dicyanoethylene, which showed significant quenching of photodecarbonylation. Irradiation of 2(S)-[(benzoyloxy)methyl]cyclobutane in acetone gave the corresponding cyclopropane as the principal product.
- Ramnauth, Jailall,Lee-Ruff, Edward
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p. 518 - 522
(2007/10/03)
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