- Palladium-Catalyzed C(sp3)-H Nitrooxylation with tert-Butyl Nitrite and Molecular Oxygen
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Herein, we report a Pd(II)-catalyzed nitrooxylation of unactivated methyl C(sp3)-H bonds using commercial available and easily manageable tert-butyl nitrite as the precursor of ONO2 radical under aerobic conditions. Environmentally benign molecular oxygen is used to initiate the generation of active radical reactant; it is also used as the terminal oxidant. A broad range of nitrooxylated aliphatic carboxamides were prepared in moderate to good yields under mild conditions.
- Han, Ye-Qiang,Li, Bo,Shi, Bing-Feng,Yang, Xu
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supporting information
p. 9719 - 9723
(2020/12/21)
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- Developing Pd(II) catalyzed double sp3 C-H alkoxylation for synthesis of symmetric and unsymmetric acetals
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An effective Pd(II) catalyzed double unactivated C(sp3)-H alkoxylation has been developed to prepare both symmetric and unsymmetric acetals. This new reaction demonstrates good functional group tolerance, excellent reactivity, and high yields. A variety of novel acetals can be readily accessed via this new method. (Chemical Equation Presented).
- Zong, Yu,Rao, Yu
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supporting information
p. 5278 - 5281
(2015/01/09)
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- Metalated nitriles: Internal 1,2-asymmetric induction
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(Chemical Equation Presented) Alkylations of conformationally constrained acyclic nitriles containing vicinal dimethyl groups and an adjacent phenyl group or trisubstituted alkene are exceptionally diastereoselective. Probing the alkylation stereoselectivity with a series of C- and N-metalated nitriles implicates a reactive conformation in which an sp2-hybridized substituent projects over the metalated nitrile to avoid allylic strain. Steric screening thereby directs the electrophilic attack to the face of the metalated nitrile opposite the projecting substituent. Excellent stereoselectively is maintained in a diverse range of alkylations that efficiently install quaternary centers, even with isopropyliodide in which a contiguous array of tertiary-quaternary-tertiary stereocenters is created! Screening the conformational requirements with a series of acyclic nitriles and esters reveals the key structural requirements for high selectivity while providing a robust, predictive model that accounts for comparable ester alkylations affording the opposite diastereomer! The intensive survey of metalated nitrile alkylations identifies the key structural features required for high 1,2-asymmetric induction, addresses the long-standing challenge of asymmetric alkylations with acylic metalated nitriles, and provides a versatile method for installing hindered quaternary centers with excellent stereocontrol.
- Fleming, Fraser F.,Liu, Wang,Ghosh, Somraj,Steward, Omar W.
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p. 2803 - 2810
(2008/09/19)
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- Conjugate addition of organolithium reagents to α,β-unsaturated carbocyclic acids
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Conjugate addition of primary, secondary, tertiary alkyi and phenyl lithium reagents to 2-alkenoic acids affords good yields of branched saturated carboxylic acids. Methyl groups at the α- and β-carbon of the 2-alkenoic acid decrease reactivity as acceptors, and foster deprotonation, respectively. The lithium enediolate resulting from the conjugate addition can react with electrophiles. PM3 calculations are in agreement with the substituent effects.
- Aurell, Maria Jose,Domingo, Luis Ramon,Mestres, Ramon,Munos, Elena,Zaragoza, Ramon Jose
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p. 815 - 830
(2007/10/03)
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- The Diastereoselectivity of Electrophilic Attack on Trigonal Carbon Adjacent to a Stereogenic Centre: Diastereoselective Alkylation and Protonation of Open-chain Enolates having a Stereogenic Centre at the β Position
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Methylation of the enolates 7, 24, 28 and 33 and protonation of the enolates 10, 27, 31 and 36 are diastereoselective in conformity to a general rule, summarised in the drawing 1, governing the stereochemistry of electrophilic attack on a double bond adjacent to a stereogenic centre.The sense of the selectivity is, with one exception, opposite to that of the corresponding nucleophilic attack on a carbonyl group adjacent to a stereogenic centre, which, with the same exception, follows Cram's and the Felkin-Anh rule, summarised in the drawing 2.The exception is probably the reduction 40 -> 38 + 39, with 39 as the major product.This result is inconsistent with Cram's and the Felkin-Anh rule if the isopropyl group is counted as 'larger' than the phenyl group, whereas the Grignard reaction 37 -> 38 + 39, where 39 is again the major product, and the corresponding electrophilic reactions 33 -> 34 + 35, with 34 as the major product, and 36 -> 34 + 35, with 35 as the major product, are all consistent with isopropyl being effectively larger than phenyl.
- Fleming, Ian,Lewis, Jeremy J.
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p. 3257 - 3266
(2007/10/02)
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- Convenient Synthetic Sequence for the Preparation of Indanones
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A convenient and general methods is reported for the synthesis of indanones from aryl ketones or aldehydes.
- Smonou, Ioulia,Orfanopoulos, Michael
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p. 1387 - 1397
(2007/10/02)
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- A Facile Method for Synthesis of Three Carbon-Homologated Carboxylic Acid by Regioselective Ring-opening of β-Propiolactones with Organocopper Reagents
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Organocopper reagents, such as diorganocuprates, organocopper-tributylphosphine, and Grignard reagents in the presence of a copper (I) salt, reacted with β-propiolactones by regioselective β-carbon-oxygen fission to give 3-substituted propionic acids.Among these three kinds of organocopper reagents, diorganocuprate, especially halomagnesium cuprate gave the highest yields of the acids, which was remarkably observed in the ring-opening of sterically hindered β-propiolactones such as β-methyl- and α,β-dimethyl-β-propiolactones and also in the reactions using the organocopper reagents with vinyl and allyl substituents.The ring-opening of β-propiolactone was confirmed to proceed by SN2 pathway with predominant inversion of configuration of the β-carbon by using the reaction of cis-α,β-dimethyl-β-propiolactone with di-tert-butylcuprate to afford syn-2,3,4,4-tetramethylpentanoic acid.
- Kawashima, Masatoshi,Sato, Toshio,Fujisawa, Tamotsu
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p. 403 - 412
(2007/10/02)
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- HIGHLY DIASTEREOSELECTIVE TANDEM ALKYLATION OF ACYCLIC α,β-UNSATURATED ESTERS BASED ON THE NOVEL USE OF DITHIOACETAL UNIT
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Highly diastereoselective tandem alkylation process of acyclic α,β-unsaturated esters was developed based on the novel use of dithioacetal as a stereocontrolling unit.
- Kawasaki, Hisashi,Tomioka, Kiyoshi,Koga, Kenji
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p. 3031 - 3034
(2007/10/02)
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- A THREE CARBON HOMOLOGATION BY THE RING-OPENING OF β-PROPIOLACTONES WITH DIORGANOCUPRATES
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Various organocuprates react with β-propiolactones to give β-substituted propionic acids in high yields.
- Fujisawa, Tamotsu,Sato, Toshio,Kawara, Tatsuo,Kawashima, Masatoshi
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p. 2181 - 2184
(2007/10/02)
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