- Palladium-Catalyzed Migratory Insertion of Carbenes and C-C Cleavage of Cycloalkanecarboxamides
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A palladium catalyzed reaction of cycloalkanecarboxamides and diazomalonates or bis(phenylsulfonyl)diazomethane has been developed. The reaction proceeds via carbene migratory insertion and cascade C-C cleavage pathways. Cycloalkanecarboxamides with four to seven membered rings are applicable in the transformation. A series of ring opening products were prepared with moderate yields. The finding provides valuable clues for the development of new reactions involving carbene migratory insertion and the cleavage of unstrained C(sp3)-C(sp3) bonds.
- Pan, Ping,Yan, Ming,Zeng, Jia,Zhang, Peng,Zhang, Xue-Jing
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supporting information
(2022/01/20)
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- Forming All-Carbon Quaternary Stereocenters by Organocatalytic Aminomethylation: Concise Access to β2,2-Amino Acids
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The asymmetric synthesis of β2,2-amino acids remains a formidable challenge in organic synthesis. Here a novel organocatalytic enantioselective aminomethylation of ketenes with stable and readily available N,O-acetals is reported, providing β2,2-amino esters bearing an all-carbon quaternary stereogenic center in high enantiomeric ratios with a catalytic amount of chiral phosphoric acid. Typically, this transformation probably proceeds through an asymmetric counter-anion-directed catalysis. As a result, a concise, practical, and atom-economic protocol toward rapidly access to β2,2-amino acids has been developed.
- Shao, Ying,Sun, Jiangtao,Tang, Shengbiao,Wang, Kai,Yu, Jianliang
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supporting information
p. 23516 - 23520
(2020/10/21)
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- Visible-light-induced oxidation/[3 + 2] cycloaddition/oxidative aromatization to construct benzo[ a]carbazoles from 1,2,3,4-tetrahydronaphthalene and arylhydrazine hydrochlorides
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An efficient synthesis of benzo[a]carbazoles via visible-light-induced tandem oxidation/[3 + 2] cycloaddition/oxidative aromatization reactions was reported. The benzylic C(sp3)-H of tetrahydronaphthalene was activated through visible-light photoredox catalyst with oxygen as the clean oxidant under mild reaction conditions. This protocol proceeds efficiently with broad substrate scope, and the mechanism study was performed.
- Shen, Jiaxuan,Li, Nannan,Yu, Yanjiang,Ma, Chunhua
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supporting information
p. 7179 - 7183
(2019/09/30)
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- A hydrochloric acid palonosetron synthesis method
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The invention relates to a new synthetic method of palonosetron hydrochloride, and belongs to the field of pharmaceutical organic synthesis. The synthetic method adopts racemized tetrahydro naphthoic acid as a raw material; a reaction is carried out with thionyl chloride and (S)-3-aminoquinuclidine; after repeated washing, (S,S)-quinuclidine tetrahydronaphthalene carboxamide is obtained; the amide is reacted with sodium borohydride and boron trifluoride diethyl etherate; the product is added into a hydrochloric acid aqueous solution to obtain the palonosetron hydrochloride. According to the method, in the amide synthetic process, ethyl acetate is used as a solvent, which reduces the generation of by-products. In addition, according to the method, in the post-treatment process, impurities are removed by phase transfer, which increases product optical purity; through repeated washing, other impurities generated in the reaction are removed, and high-purity product is obtained.
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Paragraph 0032-0034; 0035-0036; 0037-0038
(2017/08/26)
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- Origins of diastereoselectivity in lewis acid promoted ketene-alkene [2 + 2] cycloadditions
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A detailed analysis of a Lewis acid promoted ketene-alkene [2 + 2] cycloaddition is reported. The studies have led to a rationalization for an observed inversion of diastereoselectivity between thermally induced and Lewis acid promoted ketene-alkene [2 + 2] cycloadditions. The model is supported with both experimental and computational results.
- Rasik, Christopher M.,Hong, Young J.,Tantillo, Dean J.,Brown, M. Kevin
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supporting information
p. 5168 - 5171
(2014/12/11)
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- Lewis acid-promoted ketene-alkene [2 + 2] cycloadditions
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Described are the first examples of ketene-alkene [2 + 2] cycloadditions promoted by Lewis acids. Notable features of this method include (1) substantial rate acceleration relative to traditional thermal reactions, (2) good diastereoselectivities and yields for the formation of the cyclobutanone products, and (3) inverse diastereoselectivity compared with related thermal cycloadditions for many examples. These studies not only provide access to synthetically versatile cyclobutanones that cannot be prepared by traditional thermal cycloadditions but also address important mechanistic questions regarding ketene-alkene [2 + 2] cycloaddition reactions.
- Rasik, Christopher M.,Brown, M. Kevin
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supporting information
p. 1673 - 1676
(2013/04/10)
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- Synthesis of 3,3-disubstituted oxindoles by palladium-catalyzed asymmetric intramolecular α-arylation of amides: Reaction development and mechanistic studies
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Palladium complexes incorporating chiral N-heterocyclic carbene (NHC) ligands catalyze the asymmetric intramolecular α-arylation of amides producing 3,3-disubstituted oxindoles. Comprehensive DFT studies have been performed to gain insight into the mechanism of this transformation. Oxidative addition is shown to be rate-determining and reductive elimination to be enantioselectivity-determining. The synthesis of seven new NHC ligands is detailed and their performance is compared. One of them, L8, containing a tBu and a 1-naphthyl group at the stereogenic centre, proved superior and was very efficient in the asymmetric synthesis of fifteen new spiro-oxindoles and three azaspiro-oxindoles often in high yields (up to 99 %) and enantioselectivities (up to 97 % ee; ee=enantiomeric excess). Three palladacycle intermediates resulting from the oxidative addition of [Pd(NHC)] into the aryl halide bond were isolated and structurally characterized (X-ray). Using these intermediates as catalysts showed alkene additives to play an important role in increasing turnover number and frequency. Copyright
- Katayev, Dmitry,Jia, Yi-Xia,Sharma, Akhilesh K.,Banerjee, Dipshikha,Besnard, Celine,Sunoj, Raghavan B.,Kuendig, E. Peter
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supporting information
p. 11916 - 11927
(2013/09/23)
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- Asymmetric pericyclic cascade approach to spirocyclic oxindoles
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The reaction of chiral N-arylnitrones with carbocyclic alkylarylketenes generates spirocyclic oxindoles in good yields and with excellent levels of enantioselectivity (90-99% ee) via a pericyclic cascade process.
- Richmond, Edward,Duguet, Nicolas,Slawin, Alexandra M. Z.,Lebl, Tomas,Smith, Andrew D.
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supporting information; experimental part
p. 2762 - 2765
(2012/07/14)
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- Catalytic asymmetric claisen rearrangement of enolphosphonates: Construction of vicinal tertiary and all-carbon quaternary centers
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A copper-catalyzed enantioselective Claisen rearrangement of easily accessible enolphosphonates using the commercially available PhBOX as the chiral ligand was developed. A wide range of rearrangement products with contiguous tertiary and all-carbon quaternary centers were obtained in excellent yields and stereoselectivities. The α-ketophosphonate substituent in the products could be easily transformed into other functional groups. Copyright
- Tan, Jiajing,Cheon, Cheol-Hong,Yamamoto, Hisashi
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supporting information; experimental part
p. 8264 - 8267
(2012/09/08)
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- Aza-oxindole synthesis via base promoted Truce-Smiles rearrangement
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A novel efficient NaOtBu-mediated protocol for the synthesis of 3,3-disubstituted aza-oxindoles proceeds via a Truce-Smiles rearrangement- cyclisation pathway.
- Dey, Chandan,Katayev, Dmitry,Ylijoki, Kai E. O.,Kuendig, E. Peter
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supporting information
p. 10957 - 10959
(2013/01/15)
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- Aminoalkylindoles: Structure - Activity Relationships of Novel Cannabinoid Mimetics
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Aminoalkylindoles (AAIs) are a novel series of cannabinoid receptor ligands.In this report we disclose the structural features of AAIs which are important for binding to this receptor as measured by inhibition of binding of 3H>Win 55212-2 (5).Functional activity in the mouse vas deferens is also noted and used to distinguish agonists from potential antagonists.The key structural features for potent cannabinoid activity in this series are a bicyclic (naphthyl) substituent at the 3-position, a small (H) substituent at the 2-position, and an aminoethyl (morpholinoethyl) substituent at the 1-position.A 6-bromo analog, Win 54461 (31), has been identified as a potential cannabinoid receptor antagonist.Modeling experiments were done to develop a pharmacophore and also to compare AAI structures with those of classical cannabinoids.The fact that the cannabinoid AAIs arose out of work on a series of cyclooxygenase inhibitors makes sense now that an endogenous cannabinoid ligand has been identified which is a derivative of arachidonic acid.Because of their unique structures and physical properties, AAIs provide useful tools to study the structure and function of the cannabinoid receptor(s).
- Eissenstat, Michael A.,Bell, Malcolm R.,D'Ambra, Thomas E.,Alexander, E. John,Daum, Sol J.,et al.
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p. 3094 - 3105
(2007/10/02)
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