- Boron-substituted 1,3-dihydro-1,3-azaborines: Synthesis, structure, and evaluation of aromaticity
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Getting the family together: A general synthetic strategy based on nucleophilic substitution provided B-substituted 1,3-dihydro-1,3-azaborines (see scheme), BN isosteres of arenes with potential for application in biomedicine and materials science. Experi
- Xu, Senmiao,Mikulas, Tanya C.,Zakharov, Lev N.,Dixon, David A.,Liu, Shih-Yuan
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- A New Mode of Chemical Reactivity for Metal-Free Hydrogen Activation by Lewis Acidic Boranes
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We herein explore whether tris(aryl)borane Lewis acids are capable of cleaving H2 outside of the usual Lewis acid/base chemistry described by the concept of frustrated Lewis pairs (FLPs). Instead of a Lewis base we use a chemical reductant to generate stable radical anions of two highly hindered boranes: tris(3,5-dinitromesityl)borane and tris(mesityl)borane. NMR spectroscopic characterization reveals that the corresponding borane radical anions activate (cleave) dihydrogen, whilst EPR spectroscopic characterization, supported by computational analysis, reveals the intermediates along the hydrogen activation pathway. This radical-based, redox pathway involves the homolytic cleavage of H2, in contrast to conventional models of FLP chemistry, which invoke a heterolytic cleavage pathway. This represents a new mode of chemical reactivity for hydrogen activation by borane Lewis acids.
- Bennett, Elliot L.,Lawrence, Elliot J.,Blagg, Robin J.,Mullen, Anna S.,MacMillan, Fraser,Ehlers, Andreas W.,Scott, Daniel J.,Sapsford, Joshua S.,Ashley, Andrew E.,Wildgoose, Gregory G.,Slootweg, J. Chris
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supporting information
p. 8362 - 8366
(2019/05/27)
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- Neutral Fe(iv) alkylidenes, including some that bind dinitrogen
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Neutral, formally Fe(iv) alkylidene species are sought as plausible olefin metathesis catalysts, and the synthesis of several is described herein. The complexes are prepared via nucleophilic attack (Nu = MeLi, PhCH2K, 2-picolyllithium, Me2PCH2Li, MePhPCH2Li, Ph2PCH2Li) at the imine of cationic [mer-{κ-C,N,C-(C6H4-yl)-2-CH=N(2-C6H4-C(iPr)=)}Fe(PMe3)3][B(3,5-CF3-C6H3)4]. In contrast, MeMgCl and mesityllithium displaced and deprotonated bound PMe3, respectively. Structural details are provided for mer-{κ-C,N,C-(C6H4-yl)-2-CH(Bn)N(2-C6H4-C(iPr)=)}Fe{trans-(PMe3)2}N2 and {κ-C,N,C,P-(C6H4-yl)-2-CH(CH2PMe2)N(2-C6H4-C(iPr)=)}Fe(PMe3)2.
- Lindley, Brian M.,Jacobs, Brian P.,MacMillan, Samantha N.,Wolczanski, Peter T.
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supporting information
p. 3891 - 3894
(2016/03/16)
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- Fluorous synthesis of yuehchukene by α-lithiation of perfluoroalkyl-tagged 1-(arylsulfonyl)indole with mesityllithium
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Lithiation chemistry has not been well explored in fluorous synthesis because of the lack of appropriate base-resistant fluorous tags; we recently developed a perfluoroalkylated arylsulfonyl tag for the protection of the indole ring nitrogen atom. Mesityl
- Naka, Hiroshi,Akagi, Yusuke,Yamada, Kyoko,Imahori, Tatsushi,Kasahara, Takahiro,Kondo, Yoshinori
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p. 4635 - 4637
(2008/03/12)
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- Highly selective one-pot synthesis of spirophosphoranes exhibiting reversed apicophilicity by oxidation of dianions generated from P-H spirophosphorane
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(formula presented) Mild and highly selective one-pot procedures for obtaining phosphoranes that exhibit reversed (O-cis) apicophilicity are described. On the basis of the procedures, O-cis phosphorane bearing an aryl group (R = 2,4,6-tri-i-propylphenyl)
- Kajiyama, Kazumasa,Yoshimune, Miki,Nakamoto, Masaaki,Matsukawa, Shiro,Kojima, Satoshi,Akiba, Kin-Ya
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p. 1873 - 1875
(2007/10/03)
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- Lewis acid-induced internal proton return in enolate complexes with chiral amines
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Treatment of a 1:1:1 mixture of enolate 5:amine 6:lithium amide 7 with BF3·OEt2 affords the naproxen amide 4a with an enantiomer excess of 77% (>90% yield). The result is attributed to Lewis acid-induced internal proton return (ipr)
- Vedejs, Edwin,Lee, Namkyu
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p. 891 - 899
(2007/10/02)
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- Electron Transfer in the Reactions of Aryllithium Compounds with Carbon Monoxide
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The reactions of aryllithium compounds (Ar = phenyl, 1-naphthyl, xylyl, mesityl) with CO have been studied under several reaction conditions.A 13C NMR method developed to determine radicals at preparative concentrations revealed the presence of radical anions in the reaction mixtures in concentrations comparable to those of the reagents.ESR spectroscopic studies, the effect of radical inhibitors, kinetic measurements and isolation of derivatives of some intermediates suggest a mechanism that involves electron transfer as the first and rate determining step of the reaction.
- Nudelman, N. Sbarbati,Doctorovich, Fabio
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p. 4651 - 4666
(2007/10/02)
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- PHOSPHORUS-PHOSPHORUS SINGLE OR DOUBLE BOND FORMATION FROM PCl(3-n)Rn (n=1 or 2) AND A BIS-IMIDAZOLIDINE REDUCING AGENT
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1,3,1'.3'-Tetraethyl-bis(2,2'-imidazolidene), L2Et (I), is a mild homogeneous reducing agent which reduces P-Cl bonds phosphonous or phosphinous chlorides to give compounds with phosphorus-phosphorus bonds.High yields of diphosphines P2R4 are produced from the corresponding phosphinous chlorides (PClR2).Phenyl- and t-butyl-phosphonous dichlorides are reduced to cyclopolyphosphines (PR)n, which appear to be the kinetically controlled products. 2,4,6-Tri(t-butyl)phenylphosphonous dichloride (PArCl2) is reduced to either 1,2-dichloro-1,2,bis(2,4,6-tri-t-butylphenyl)diphosphine (PArCl)2 or trans-bisdiphosphene (P2Ar2) depending on the initial stoichiometry.
- Goldwhite, Harold,Kaminski, John,Millhauser, Glenn,Ortiz, Jesus,Vargas, Maurice,et al.
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- The 2p?*-3d? Interaction in Aromatic Silanes Fluorescence from the 1(2p?, 3d?) Intramolecular Charge-transfer State
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The 2p?*-3d? interaction in the excited state of aromatic silanes has been studied by means of absorption and emission spectroscopy.Broad and structureless fluorescence spectra of phenyldisilanes and naphthyldisilanes with large Stokes shifts h
- Shizuka, Haruo,Sato, Yoshihiro,Ueki, Yutaka,Ishikawa, Mitsuo,Kumada, Makoto
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p. 341 - 358
(2007/10/02)
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- Preparation of 1,3-Diketones and of Nitro-diketones by (1:1)-Acylation of Lithium Enolates with Acyl Chlorides
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Slow addition of precooled solutions of lithium enolates in THF to solutions of equimolar amounts of acyl chlorides in the same solvent at temperatures between -80 and -100 deg furnishes 1,3-diketones in acceptable to good yields.Even 3-nitropropionyl and 4-nitrobutyryl chloride can be employed for the (1:1)-acylation of enolates to give the synthetically useful 5- and 6-nitro-1,3-diketones 13 and 25, respectively.The scope and the limitations of this method of preparing 1,3-diketones are given and are compared with alternative methods.
- Seebach, Dieter,Weller, Thomas,Protschuk, Gerd,Beck, Albert K.,Hoekstra, Marvin S.
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p. 716 - 735
(2007/10/02)
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