- Chiral Nanoparticles/Lewis Acids as Cooperative Catalysts for Asymmetric 1,4-Addition of Arylboronic Acids to α,β-Unsaturated Amides
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Cooperative catalysts consisting of chiral Rh/Ag nanoparticles and Sc(OTf)3have been developed that catalyze asymmetric 1,4-addition reactions of arylboronic acids with α,β-unsaturated amides efficiently. The reaction has been considered one of
- Yasukawa, Tomohiro,Saito, Yuuki,Miyamura, Hiroyuki,Kobayashi, Shū
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- β-Substituted γ-butyrolactams from mucochloric acid: Synthesis of (±)-baclofen and other γ-aminobutyric acids and useful building blocks
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In the course of our exploration of the application of mucohalic acids in organic synthesis, we reported the synthesis of α,β-dihalo-α, β-unsaturated γ-butyrolactams by reductive amination of a suitable mucohalic acid and a suitable amine. However, the functionalization of the α- and/or β-halogen was found to be elusive under Suzuki conditions that worked well with the corresponding γ-lactones. Although the corresponding β-aryl derivative was obtained under some of the modified Suzuki conditions tried, the yields were found to be very low. Next, the Suzuki coupling was performed on mucochloric acid prior to the reductive amination step. By careful control of the reaction conditions, only β-substitution was achieved to yield the corresponding β-aryl mucochloric acid. This could then be converted to the corresponding β-substituted γ-butyrolactam by reductive amination with 2,4-dimethoxybenzylamine (DMB-NH2) followed by reduction by nickel boride and subsequent deprotection of the DMB group. The resulting γ-butyrolactam could either be alkylated or hydrolyzed resulting in the corresponding β-substituted γ-aminobutyric acid. This methodology was extended to synthesize (±)-baclofen in five steps starting from mucochloric acid.
- Biswas, Kallolmay,Gholap, Rajesh,Srinivas, Padakanti,Kanyal, Sachin,Sarma, Koushik Das
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p. 2538 - 2545
(2014/01/06)
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- Rhodium-catalyzed domino conjugate addition-cyclization reactions for the synthesis of a variety of N- and O-heterocycles: Arylboroxines as effective carbon nucleophiles
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Facile and efficient Rh(I)-catalyzed domino conjugate addition-cyclization reactions of olefins bearing two electrophilic sites and a pendant nucleophile with organoboroxines have been developed to afford a variety of N- and O-heterocycles, such as 3,4-dihydroquinolin-2(1H)-ones, 3,4-dihydrocoumarins, and pyrrolidin-2-ones, which constitute important motifs in biologically active natural and synthetic organic compounds.
- Park, Ja Ock,Youn, So Won
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supporting information; experimental part
p. 2258 - 2261
(2010/07/17)
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- New ring expansion of cyclobutanones: Synthesis of pyrrolinones, pyrrolidines and pyrroles
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2,2-Dichlorocyclobutanones reacted with various amines to give ring opening leading to 4,4-dichlorobutanamides. These compounds proved to be suitable substrates for the synthesis of 3-pyrrolin-2-ones, 2-pyrrolidinones, pyrrolidines and pyrroles.
- Verniest, Guido,Boterberg, Stefaan,Bombeke, Filip,Stevens, Christian V.,De Kimpe, Norbert
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p. 1059 - 1063
(2007/10/03)
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- Rhodium(I)-catalysed hydrocarbonylation and silylcarbonylation reactions of alkynes in the presence of primary amines leading to 2-pyrrolidinones and 4-silylated 1-aza-1,3-butadienes
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Rh(I)-catalysed hydrocarbonylation of alkynes 1 in the presence of primary amines gives substituted 2-pyrrolidinones 3 in a one-pot procedure. Replacement of hydrogen by hydrosilanes via silylcarbonylation leads to 4- silylated l-aza-l,3-butadienes 5. The
- Baerfacker, Lars,Hollmann, Christoph,Eilbracht, Peter
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p. 4493 - 4506
(2007/10/03)
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- Radical cyclization in heterocycle synthesis. II. Total synthesis of (±)-anantine and (±)-isoanantine
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(+)-Anantine, (±)-isoanantine and related compounds were synthesized via two key reactions, sulfanyl radical addition-cyclization and stereoselective construction of the E-benzylidene moiety.
- Naito, Takeaki,Honda, Yuko,Bhavakul, Vanida,Yamaguchi, Sayaka,Fujiwara, Azusa,Miyata, Okiko,Ninomiya, Ichiya
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p. 1932 - 1939
(2007/10/03)
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- Synthetic Versatility of N(Silylmethyl)imines: Water-Induced Generation of N-Protonated Azomethine Ylides of Nonstabilized Type and Fluoride-Induced Generation of 2-Azallyl Anions
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N-(Silylmethyl)imines generate N-protonated azomethine ylides of nonstabilized type when treated with water in HMPA, which undergo stereospecific and regioselective cycloadditions with electron-poor olefins affording N-unsubstituted pyrrolidines.On the other hand, fluoride-induced desilylation of the imines leads to 2-azallyl anions which are found to be synthetic equivalents of aminomethyl anion in the Michael additions with electron-poor olefins and nucleophilic additions with carbonyl compounds.
- Tsuge, Otohiko,Kanemasa, Shuji,Hatada, Akira,Matsuda, Koyo
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p. 2537 - 2546
(2007/10/02)
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