- Reactivity of (bi-Oxazoline)organonickel Complexes and Revision of a Catalytic Mechanism
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Bi-Oxazoline (biOx) has emerged as an effective ligand framework for promoting nickel-catalyzed cross-coupling, cross-electrophile coupling, and photoredox-nickel dual catalytic reactions. This report fills the knowledge gap of the organometallic reactivity of (biOx)Ni complexes, including catalyst reduction, oxidative electrophile activation, radical capture, and reductive elimination. The biOx ligand displays no redox activity in (biOx)Ni(I) complexes, in contrast to other chelating imine and oxazoline ligands. The lack of ligand redox activity results in more negative reduction potentials of (biOx)Ni(II) complexes and accounts for the inability of zinc and manganese to reduce (biOx)Ni(II) species. On the basis of these results, we revise the formerly proposed “sequential reduction” mechanism of a (biOx)Ni-catalyzed cross-electrophile coupling reaction by excluding catalyst reduction steps.
- Ju, Luchuan,Lin, Qiao,LiBretto, Nicole J.,Wagner, Clifton L.,Hu, Chunhua Tony,Miller, Jeffrey T.,Diao, Tianning
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supporting information
p. 14458 - 14463
(2021/09/18)
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- Self-organisation through size-exclusion in soft materials
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A number of materials derived from 4-undecyloxy-4′-cyanobiphenyl but with varying terminal groups were prepared in order to better understand how such a group influences the type, and local structure of mesophases formed. Whereas electron poor terminal groups (fluoroaromatics and halogen atoms) were found to destabilise the smectic A phase through unfavourable electrostatic interactions, bulky silane, siloxane and hydrocarbon groups can be incorporated into the structure of the phase with only minor reductions in clearing point. An increase in the layer spacing of the smectic Ad phase in materials with bulky groups suggests that microphase segregation is not the driving force, but rather exists as a consequence of steric crowding at the smectic layer interface. Electrooptic studies reveal that 'carbosilane' end groups, such as tetramethyldisilapropane, are significantly more electrochemical stable than their siloxane counterparts whilst retaining their desirable thermal properties.
- Mandle, Richard J.,Davis, Edward J.,Voll, Constantin-Christian A.,Lewis, Daniel J.,Cowling, Stephen J.,Goodby, John W.
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supporting information
p. 2380 - 2388
(2015/04/14)
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- Total synthesis of the aglycone of IB-00208
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Abstract A total synthesis of the aglycone of IB-00208 was accomplished in 22 steps using a newly developed approach towards polycyclic 1,4-dioxygenated xanthones from benzocyclobutenones. The generality of this entry to xanthones was initially established on several model systems before it was successfully applied to the construction of the hexacyclic core of the natural product. A new and potentially general approach towards angularly fused benzocyclobutenones using ring-closing metathesis (RCM) was also developed.
- Knueppel, Daniel,Yang, Jingyue,Cheng, Bo,Mans, Douglas,Martin, Stephen F.
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p. 5741 - 5757
(2015/08/03)
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- Palladium-catalyzed kumada coupling reaction of bromoporphyrins with silylmethyl grignard reagents: Preparation of silylmethyl-substituted porphyrins as a multipurpose synthon for fabrication of porphyrin systems
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We have developed an efficient method for preparing silylmethyl-substituted porphyrins via the palladium-catalyzed Kumada cross-coupling reaction of bromoporphyrins with silylmethyl Grignard reagents. We demonstrated the synthetic utility of these silylmethylporphyrins as a multipurpose synthon for fabricating porphyrin derivatives through a variety of transformations of the silylmethyl groups, including the DDQ-promoted oxidative conversion to CHO, CH2OH, CH2OMe, and CH2F functionalities and the fluoride ion-mediated desilylative introduction of carbona-carbon single and double bonds.
- Sugita, Noriaki,Hayashi, Satoshi,Hino, Fumio,Takanami, Toshikatsu
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p. 10488 - 10497
(2013/02/22)
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- Cobalt-catalyzed alkenylation of thiazoles with alkynes via C-H bond functionalization
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A cobalt-Xantphos catalyst has been developed for the syn addition of (benzo)thiazoles to internal alkynes via C-H bond functionalization. The reaction affords C2-alkenylated (benzo)thiazoles with high regio- and stereoselectivities under mild conditions. Georg Thieme Verlag Stuttgart. New York.
- Ding, Zhenhua,Yoshikai, Naohiko
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experimental part
p. 2561 - 2566
(2011/10/02)
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- MACROCYCLIC COMPOUNDS AND METHODS OF MAKING AND USING THEREOF
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Described herein are tricyclic macrolactones. The macrolactones have a high binding affinity for PKC. The compounds described herein can be used in a number of therapeutic applications including cancer and Alzheimer's prevention and treatment. The compounds described herein can also treat memory loss. Also described herein are methods for producing macrolactones. The methods permit the high-yield synthesis of macrolactones in fewer steps and with a higher degree of substitution and specificity.
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Page/Page column 31-32; 93
(2009/12/02)
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- Fluorination process
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Compounds of formula (II), (IIIa) or (IIIb) (variables are described in the specification) are prepared by fluorination of β,γ-unsaturated alkyl silanes. These compounds are useful as building blocks in the pharmaceutical industry.
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Page/Page column 35
(2008/06/13)
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- Cobalt-catalyzed mono-coupling of R3SiCH2MgCl with 1,2-dihalogenoethylene: A general route to γ-substituted (E)-allylsilanes
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The reaction of trimethylsilylmethylmagnesium chloride (TMSCH 2MgCl) with 1,2-dihalogenoethylene in the presence of 1mol% of Co(II) or Co(III) acetylacetonate in THF or THF-NMP proceeded exclusively in a mono-coupling pathway to provide 3-trimethylsilyl-1-halogeno-1-propene with >99% of E geometry in high yield, which was converted to a variety of γ-substituted allylsilanes by Ni- or Pd-catalyzed coupling with organometallic compounds.
- Kamachi, Taku,Kuno, Akiko,Matsuno, Chikashi,Okamoto, Sentaro
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p. 4677 - 4679
(2007/10/03)
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- 2-(TRIFLUOROMETHYL)ALLYLTRIMETHYLSILANE. A USEFUL BUILDING BLOCK FOR TRIFLUOROMETHYLATED ORGANIC MOLECULES
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2-(Trifluoromethyl)allyltrimethylsilane, a new building block for the introduction of trifluoromethyl group was prepared by the Grignard reaction of ethyl trifluoroacetate with (trimethylsilyl)methylmagnesium chloride.This allylsilane underwent the reaction with aldehydes and ketones to give the adducts in good yields.
- Yamazaki, Takashi,Ishikawa, Nobuo
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p. 521 - 524
(2007/10/02)
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- Action d'organometalliques fonctionnels sur des gem-aminoethers et des sels d'immonium. I. Synthese d'amines α- ou β-fonctionnelles difficilement accessibles par reaction de Mannich
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Some α- or β-functional amines which are difficult to obtain by Mannich reaction can be easily prepared from organomagnesium or organozinc functional derivatives and gem-aminoethers or immonium salts.
- Courtois, Gilles,Miginiac, Philippe
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p. 395 - 400
(2007/10/02)
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