3019-25-8Relevant academic research and scientific papers
PdII-Catalyzed Enantioselective C(sp3)–H Arylation of Cyclobutyl Ketones Using a Chiral Transient Directing Group
Ewing, William R.,Hong, Kai,Hu, Liang,Luo, Fan,Xiao, Li-Jun,Yeung, Kap-Sun,Yu, Jin-Quan
, p. 9594 - 9600 (2020/04/17)
The use of chiral transient directing groups (TDGs) is a promising approach for developing PdII-catalyzed enantioselective C(sp3)?H activation reactions. However, this strategy is challenging because the stereogenic center on the TDG is often far from the C?H bond, and both TDG covalently attached to the substrate and free TDG are capable of coordinating to PdII centers, which can result in a mixture of reactive complexes. We report a PdII-catalyzed enantioselective β-C(sp3)?H arylation reaction of aliphatic ketones using a chiral TDG. A chiral trisubstituted cyclobutane was efficiently synthesized from a mono-substituted cyclobutane through sequential C?H arylation reactions, thus demonstrating the utility of this method for accessing structurally complex products from simple starting materials. The use of an electron-deficient pyridone ligand is crucial for the observed enantioselectivity. Interestingly, employing different silver salts can reverse the enantioselectivity.
Preparation method of novel anti-ultraviolet plastic additive
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Paragraph 0016; 0017; 0018, (2017/11/29)
The invention discloses a preparation method of a novel anti-ultraviolet plastic additive and belongs to the technical field of plastic additive synthesis. The novel anti-ultraviolet plastic additive has a structure described in the specification, wherein R1 is an oxygen atom or nitrogen atom; and R2 is cyclopentane, cyclobutane or cyclopropane; and R3 is methyl, ethyl or phenyl. The invention also discloses a preparation method of the novel anti-ultraviolet plastic additive. According to the invention, a new anti-ultraviolet plastic additive is synthesized by virtue of a new method, reaction process operation is simple and practicable, raw materials are cheap and available, reaction efficiency is relatively high and repeatability is relatively good, and the novel anti-ultraviolet plastic additive has a good anti-ultraviolet radiation ageing effect on plastic.
Synthetic method of novel feed additive
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Paragraph 0016; 0017; 0018, (2017/12/06)
The invention discloses a synthetic method of a novel feed additive and belongs to the technical field of synthesis of feed additives. The novel feed additive has the structure shown in the specification, wherein R1 is an oxygen atom or a nitrogen atom, R2 is cyclopentane, cyclobutane or cyclopropane, and R3 is methyl, ethyl or phenyl. The invention further discloses a preparation method of the novel feed additive. The novel feed additive is synthesized with the novel method, operation is simple and easy to perform in the reaction process, raw materials are low in price and easy to obtain, the reaction efficiency is relatively high, the repetition is relatively good, and the novel feed additive has a good growth promoting function on grow-finishing pigs.
A S1P - 1 receptor agonist pharmaceutical molecule novel synthesis method (by machine translation)
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Paragraph 0022; 0023; 0024, (2018/01/04)
The invention discloses a S1P - 1 receptor agonist pharmaceutical molecular synthesis method, which belongs to the technical field of medical synthesis. Technical proposal of the invention points are: a S1P - 1 receptor agonist pharmaceutical molecular synthesis method, has the following structure: The invention also discloses the S1P - 1 receptor agonist pharmaceutical molecule of the preparation method. The invention a new method to synthesize a S1P - 1 receptor agonist drug molecules, the reaction process is simple and easy operation, the raw material is cheap, relatively high reaction efficiency and good repeatability, anti-platelet aggregation effect is obvious. (by machine translation)
A Stereoselective Synthesis of a 3,4,5-Substituted Piperidine of Interest as a Selective Muscarinic (M1) Receptor Agonist
Broadley, Kenneth J.,Buffat, Maxime G. P.,Davies, Robin H.,Thomas, Eric J.
, p. 45 - 50 (2015/12/26)
A stereoselective synthesis of (1RS,2SR,6SR)-7-benzyl-6-cyclo-butyl-2-methoxymethyl-4,7-diaza-9-oxobicyclo[4.3.0]nonan-8-one, which is representative of a novel series of selective muscarinic (M1) receptor agonists, is described.
Stereoselective synthesis of oxazolidinonyl-fused piperidines of interest as selective muscarinic (M1) receptor agonists: A novel M1 allosteric modulator
Broadley, Kenneth J.,Buffat, Maxime G. P.,Burnell, Erica,Davies, Robin H.,Moreau, Xavier,Snee, Stephen,Thomas, Eric J.
, p. 2057 - 2089 (2016/02/18)
Syntheses of (1RS,2SR,6SR)-2-alkoxymethyl-, 2-hetaryl-, and 2-(hetarylmethyl)-7-arylmethyl-4,7-diaza-9-oxabicyclo[4.3.0]nonan-8-ones, of interest as potential muscarinic M1 receptor agonists, are described. A key step in the synthesis of (1RS,2SR,6SR)-7-benzyl-6-cyclobutyl-2-methoxymethyl-4,7-diaza-9-oxabicyclo[4.3.0]nonan-8-one, was the addition of isopropenylmagnesium bromide to 2-benzyloxycarbonylamino-3-tert-butyldimethylsilyloxy-2-cyclobutylpropanal. This gave the 4-tert-butyldimethylsilyloxymethyl-4-cyclobutyl-5-isopropenyloxazolidinone with the 5-isopropenyl and 4-tert-butyldimethylsilyloxymethyl groups cis-disposed about the five-membered ring by chelation controlled addition and in situ cyclisation. This reaction was useful for a range of organometallic reagents. The hydroboration-oxidation of (4SR,5RS)-3-benzyl-4-(tert-butyldimethylsilyloxymethyl)-4-cyclobutyl-5-(1-methoxyprop-2-en-2-yl)-1,3-oxazolidin-2-one gave (4SR,5RS)-3-benzyl-4-(tert-butyldimethylsilyloxymethyl)-4-cyclobutyl-5-[(SR)-1-hydroxy-3-methoxyprop-2-yl]-1,3-oxazolidin-2-one stereoselectively. 4,7-Diaza-9-oxabicyclo[4.3.0]nonan-8-ones with substituents at C2 that could facilitate C2 deprotonation were unstable with respect to oxazolidinone ring-opening and this restricted both the synthetic approach and choice of 2-heteroaryl substituent. The bicyclic system with a 2-furyl substituent at C2 was therefore identified as an important target. The addition of 1-lithio-1-(2-furyl)ethene to 2-benzyloxycarbonylamino-3-tert-butyldimethylsilyloxy-2-cyclobutylpropanal gave (4SR,5RS)-4-tert-butyldimethylsilyloxymethyl-4-cyclobutyl-5-[1-(2-furyl)ethenyl]-1,3-oxazolidinone after chelation controlled addition and in situ cyclisation. Following oxazolidinone N-benzylation, hydroboration at 35 °C, since hydroboration at 0 °C was unexpectedly selective for the undesired isomer, followed by oxidation gave a mixture of side-chain epimeric alcohols that were separated after SEM-protection and selective desilylation. Conversion of the neopentylic alcohols into the corresponding primary amines by reductive amination, was followed by N-nosylation, removal of the SEM-groups and cyclisation using a Mitsunobu reaction. Denosylation then gave the 2-furyloxazolidinonyl-fused piperidines, the (1RS,2SR,6SR)-epimer showing an allosteric agonistic effect on M1 receptors. Further studies resulted in the synthesis of other 2-substituted 4,7-diaza-9-oxabicyclo[4.3.0]nonan-8-ones and an analogous tetrahydropyran.
A convenient preparation of cyclobutyl ketones: Naphthalene-catalyzed reductive cyclization of substituted 1,4-dihalobutanes
Ramig, Keith,Dong, Yong,Van Arnum, Susan D.
, p. 443 - 446 (2007/10/02)
Acyl-substituted succinates are useful starting materials for the synthesis of cyclobutyl ketones. The key step, reductive cyclization of the intermediate dihalide, afforded yields of 32-60% of cyclobutyl-containing products.
Vinyl Cations, 36. Solvolysis of Cycloalkylidenemethyl and 1-Cyclopenten-1-yl Triflates
Hanack, Michael,Maerkl, Rainer,Martinez, Antonio Garcia
, p. 772 - 782 (2007/10/02)
Cyclohexylidenemethyl triflate (2), cyclobutylidenemethyl triflate (5), 1-cyclopenten-1-yl triflate (7), bicyclohex-2-en-2-yl triflate (9), 1-cyclobutylideneethyl triflate (19), and 2-methyl-1-cyclopenten-1-yl triflate (29) were solvolyzed in solvents of various ionizing power and nucleophilicity and the solvolysis products were identified.The cyclobutylidenealkyl triflates solvolyze via a vinyl cation mechanism involving ion pairs with rearrangement to cyclopentene and cyclopentanone compounds.The 1-cyclopenten-1-yl triflates do not produce vinyl cation intermediates but give only the corresponding ketones via an O - S bond cleavage of the triflate group.
Wanderungstendenzen cyclischer, polycyclischer und methylverzweigter Alkylreste bei der Beckmann-Umlagerung
Langhals, Heinz,Ruechardt, Christoph
, p. 3831 - 3854 (2007/10/02)
The migration aptitudes of polycyclic bridgehead groups, cycloalkyl groups as well as of β-, γ- and δ-branched alkyl groups in the Chapman variant of the Beckmann rearrangement were determined.From these data it is concluded that at transition state 2 the migrating group is not resembling a planarised carbenium ion R+, but rather a pentacoordinated carbonium ion structure.Because only small geometrical changes occur in the migrating group vertical stabilisation of charge at transition state is believed to have significant influence on the migration aptitudes.
