- Streamlined Catalytic Enantioselective Synthesis of α-Substituted β,γ-Unsaturated Ketones and Either of the Corresponding Tertiary Homoallylic Alcohol Diastereomers
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A widely applicable, practical, and scalable strategy for efficient and enantioselective synthesis of β,γ-unsaturated ketones that contain an α-stereogenic center is disclosed. Accordingly, aryl, heteroaryl, alkynyl, alkenyl, allyl, or alkyl ketones that contain an α-stereogenic carbon with an alkyl, an aryl, a benzyloxy, or a siloxy moiety can be generated from readily available starting materials and by the use of commercially available chiral ligands in 52-96% yield and 93:7 to >99:1 enantiomeric ratio. To develop the new method, conditions were identified so that high enantioselectivity would be attained and the resulting α-substituted NH-ketimines, wherein there is strong CN → B(pin) coordination, would not epimerize before conversion to the derived ketone by hydrolysis. It is demonstrated that the ketone products can be converted to an assortment of homoallylic tertiary alcohols in 70-96% yield and 92:8 to >98:2 dr - in either diastereomeric form - by reactions with alkyl-, aryl-, heteroaryl-, allyl-, vinyl-, alkynyl-, or propargyl-metal reagents. The utility of the approach is highlighted through transformations that furnish other desirable derivatives and a concise synthesis route affording more than a gram of a major fragment of anti-HIV agents rubriflordilactones A and B and a specific stereoisomeric analogue.
- Pozo, Juan Del,Zhang, Shaochen,Romiti, Filippo,Xu, Shibo,Conger, Ryan P.,Hoveyda, Amir H.
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supporting information
p. 18200 - 18212
(2020/11/02)
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- ABSCISIC ACID DERIVATIVE
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The compound represented by formula (IV) or a salt thereof has an inhibitory action on an abscisic acid receptor. The compound or the salt thereof can be used as a plant growth regulator. wherein X is an ethylene group, an ethenylene group or an ethynyle
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- Photoredox-catalyzed oxytrifluoromethylation of allenes: Stereoselective synthesis of 2-trifluoromethylated allyl acetates
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We have developed novel oxytrifluoromethylation of aryl-substituted allenes by photoredox catalysis. The present photocatalytic system allows direct and stereoselective synthesis of 2-CF3-allyl acetates bearing tetrasubstituted CF3-a
- Tomita, Ren,Koike, Takashi,Akita, Munetaka
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supporting information
p. 4681 - 4684
(2017/07/10)
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- Copper-Catalyzed Intermolecular Trifluoromethylazidation and Trifluoromethylthiocyanation of Allenes: Efficient Access to CF3-Containing Allyl Azides and Thiocyanates
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A mild and efficient method for copper-catalyzed trifluoromethylazidation and trifluoromethylthiocyanation of allenes was explored. A series of CF3-containing allyl azides and thiocyanates were obtained with high yields and good stereoselectivi
- Zhu, Na,Wang, Fei,Chen, Pinhong,Ye, Jinxing,Liu, Guosheng
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p. 3580 - 3583
(2015/07/28)
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- Click chemistry route to tricyclic monosaccharide triazole hybrids: Design and synthesis of substituted hexahydro-4H-pyrano[2,3-f][1,2,3]triazolo[5,1-c][1,4]oxazepines
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A click chemistry approach to novel tricyclic monosaccharide triazole hybrids, namely, aryl substituted hexahydro-4H-pyrano[2,3-f][1,2,3]triazolo[5,1-c][1,4]oxazepine derivatives from an intramolecular 1,3-dipolar cycloaddition of 6-azido-4-O-propargyl glycopyranosides has been reported.
- Konda, Saidulu,Rao, Pallavi,Oruganti, Srinivas
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p. 63962 - 63965
(2015/02/19)
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- Fused ring aziridines as a facile entry into triazole fused tricyclic and bicyclic heterocycles
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The intramolecular dipolar cycloaddition of an azide with an alkyne has provided a useful entry into triazole fused tricyclic heterocycles containing both the triazole ring and the oxazolidin-2-one ring system. The requisite azido-alkynes have been prepared via a two-step sequence from fused ring aziridines. A series of 6-12 membered rings containing both the oxazolidinone and triazole rings have been prepared. These ring systems have been designed as conformationally restrained analogs of RNA-binding oxazolidinones. The Royal Society of Chemistry 2012.
- Fang, Fang,Vogel, Megan,Hines, Jennifer V.,Bergmeier, Stephen C.
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p. 3080 - 3091
(2012/05/07)
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- Regioselective radical bromoallylation of allenes leading to 2-bromo-substituted 1,5-dienes
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The regioselective radical bromoallylation of allenes proceeded efficiently in the presence of AIBN as a radical initiator to give 2-bromo-substituted 1,5-dienes in excellent yields. The addition of a bromine radical took place regioselectively onto the central carbon of allenes generating a stable allyl radical, which underwent addition/β-fragmentation reactions with allylbromides. The products could be further functionalized by Pd-catalyzed coupling reactions.
- Kippo, Takashi,Fukuyama, Takahide,Ryu, Ilhyong
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p. 3864 - 3867
(2011/09/15)
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- Aza cope rearrangement of propargyl enammonium cations catalyzed by a self-assembled "nanozyme"
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The tetrahedral assembly [Ga4L6]12- [L = N,N-bis(2,3-dihydroxybenzoyl)-1,5-diaminonaphthalene) encapsulates a variety of cations, including propargyl enammonium cations capable of undergoing the aza Cope rearrangement. For propargyl enammonium substrates that are encapsulated in the [Ga4L6]12- assembly, rate accelerations by factors of up to 184 compared with the background reaction rate were observed. After rearrangement, the product iminium ion is released into solution and hydrolyzed, allowing for catalytic turnover. The activation parameters for the catalyzed and uncatalyzed reaction were determined, revealing that a decrease in the entropy of activation is responsible for the observed rate enhancements. The catalyzed reaction exhibits saturation kinetics: the rate data obeyed the Michaelis-Menten model of enzyme kinetics, and competitive inhibition using a nonreactive guest was demonstrated.
- Hastings, Courtney J.,Fiedler, Dorothea,Bergman, Robert G.,Raymond, Kenneth N.
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supporting information; experimental part
p. 10977 - 10983
(2009/02/05)
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- Reduction of propargylic sulfones to (Z)-allylic sulfones using zinc and ammonium chloride
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Propargylic sulfones can be cis-hydrogenated using commercial zinc powder and ammonium chloride in THF-water at room temperature, the major products being the corresponding (Z)-allylic sulfones. Other reducible groups (alkene, benzyloxy) are not affected. Allenylsulfones are implicated in one of the possible reaction pathways.
- Sheldrake, Helen M.,Wallace, Timothy W.
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p. 4407 - 4411
(2008/02/03)
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- Microbicidal N-sulfonylglycin alkynyloxyphenethyl amide derivatives
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The invention relates to novel pesticidally active compounds of the general formula I as well as possible isomers and mixtures of isomers thereof, wherein n is a number zero or one; and R1is C1-C12alkyl that is unsubstituted or may be substituted by C1-C4alkoxy, C1-C4alkylthio, C1-C4alkylsulfonyl, C3-C8cycloalkyl, cyano, C1C6alkoxycarbonyl, C3-C6alkenyloxycarbonyl or by C3-C6alkynyloxycarbonyl; C3-C8cycloalkyl; C2-C12alkenyl; C2-C12alkynyl; C1-C12haloalkyl: or a group NR11R12wherein R11and R12are each independently of the other hydrogen or C1-C8alkyl, or together are tetra- or penta-methylene; R2and R3are each independently of the other hydrogen; C1-C8alkyl; C1-C8alkyl substituted by hydroxy, C1-C4alkoxy, mercapto or by C1-C4alkylthio; C3-C8alkenyl; C3-C8alkynyl; C3-C8cycloalkyl; C3-C8cycloalkyl-C1-C4alkyl; or the two groups R2and R3together with the carbon atom to which they are bonded form a three- to eight-membered ring; R4, R5, R6and R7are identical or different and are each independently of the others hydrogen or C1-C4alkyl; R8is C1-C6alkyl, C3-C6alkenyl or C3-C6alkynyl; A is C1-C6alkylene; and B is optionally mono- or poly-nuclear, unsubstituted or substituted aryl; optionally mono- or poly-nuclear, unsubstituted or substituted heteroaryl; C4-C12alkyl; or C3-C8cycloalkyl. The novel compounds have plant-protecting properties and are suitable for protecting plants against infestation by phytopathogenic microorganisms.
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- PREPARATION OF STEREOCHEMICALLY PURE OXIMES WITH MUSCARINIC ACTIVITY
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The instant invention is a selective formation of the Z-oxime and O-alkylation of 1-azabicyclo[2.2.1]heptan-3-one and 1-azabicyclo[2.2. 2] heptan-3-one oximes to produce compounds with muscarinic activity. The process is capable of scale-up for industrial purposes as it provides better yields and ease of preparation. Intermediates are also described.
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- Practical and Safe Sulfonylation of 2-Alkynyl and 2-Alkenyl Alcohols Using the Combined Bases of a Catalytic Amount of Tertiary Amine and Potassium Carbonate
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Several 2-alkynyl and 2-alkenyl alcohols were effectively sulfonylated with methanesulfonyl chloride or p-toluenesulfonyl chloride using the combined bases of a catalytic amount of tertiary amine and potassium carbonate.The reaction was conducted with reliable safety and while avoiding the disposal of wasted amines.The mesylation of 2-propyn-1-ol proceeded on a large scale (more than 20 kg) without a substantial production of explosive 3-chloro-1-propyne.The choice of the catalysts was important, and sterically unhindered tertiary amines, such as trimethylamine, N,N-d imethylbenzylamine, and triethylamine, were effective.Without these catalysts the reactions were significantly retarded.The reaction was so mild that it could be applied to complex and optically active 4-hydroxy-3-methyl-2-(2-propynyl)-2-cyclopenten-1-one, which is an important alcohol moiety of synthetic pyrethroids.
- Tanabe, Yoo,Yamamoto, Hitomi,Yoshida, Yoshihiro,Miyawaki, Takashi,Utsumi, Naoka
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p. 297 - 300
(2007/10/02)
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