2769-71-3Relevant articles and documents
Heterocyclopentanediyls vs heterocyclopentadienes: A question of silyl group migration
Beer, Henrik,Bresien, Jonas,Michalik, Dirk,R?lke, Anne-Kristin,Schulz, Axel,Villinger, Alexander,Wustrack, Ronald
supporting information, p. 14435 - 14445 (2020/12/29)
The reaction of the singlet biradical [P(μ-NHyp)]2 (Hyp = hypersilyl, (Me3Si)3Si) with different isonitriles afforded a series of five-membered N2P2C heterocycles. Depending on the steric bulk of the substituent at the isonitrile, migration of a Hyp group was observed, resulting in two structurally similar but electronically very different isomers. As evidenced by comprehensive spectroscopic and theoretical studies, the heterocyclopentadiene isomer may be regarded as a rather unreactive closed-shell singlet species with one localized N=P and one C=P double bond, whereas the heterocyclopentanediyl isomer represents an open-shell singlet biradical with interesting photochemical properties, such as photoisomerization under irradiation with red light to a [2.1.0]- housane-type species.
Isocyanide 2.0
Ahmadian-Moghaddam, Maryam,D?mling, Alexander,Patil, Pravin
supporting information, p. 6902 - 6911 (2020/11/09)
The isocyanide functionality due to its dichotomy between carbenoid and triple bond characters, with a nucleophilic and electrophilic terminal carbon, exhibits unusual reactivity in organic chemistry exemplified for example in the Ugi reaction. Unfortunately, the over proportional use of only a few isocyanides hampers novel discoveries about the fascinating reactivity of this functional group. The synthesis of a broad range of isocyanides with multiple functional groups is lengthy, inefficient, and exposes the chemist to hazardous fumes. Here we present an innovative isocyanide synthesis overcoming these problems by avoiding the aqueous workup which we exemplify by parallel synthesis from a 0.2 mmol scale performed in 96-well microtiter plates up to a 0.5 mol multigram scale. The advantages of our methodology include an increased synthesis speed, very mild conditions giving access to hitherto unknown or highly reactive classes of isocyanides, rapid access to large numbers of functionalized isocyanides, increased yields, high purity, proven scalability over 5 orders of magnitude, increased safety and less reaction waste resulting in a highly reduced environmental footprint. For example, the hitherto believed to be unstable 2-isocyanopyrimidine, 2-acylphenylisocyanides and even o-isocyanobenzaldehyde could be accessed on a preparative scale and their chemistry was explored. Our new isocyanide synthesis will enable easy access to uncharted isocyanide space and will result in many discoveries about the unusual reactivity of this functional group. This journal is
Reversible switching between housane and cyclopentanediyl isomers: An isonitrile-catalysed thermal reverse reaction
Beer, Henrik,Bresien, Jonas,Michalik, Dirk,Schulz, Axel,Villinger, Alexander
supporting information, p. 13986 - 13992 (2020/11/02)
The photo-isomerization of an isolable five-membered singlet biradical based on C, N, and P ([TerNP]2CNDmp, 2a) selectively afforded a closed-shell housane-type isomer (3a) by forming a transannular P-P bond. In the dark, the housane-type species re-isomerized to the biradical, resulting in a fully reversible overall process. In the present study, the influence of tBuNC on the thermal reverse reaction was investigated: The isonitrile acted as a catalyst, thus allowing control over the thermal reaction rate. Moreover, tBuNC also reacted with the biradical to form an adductspecies ([TerNP]2CNDmp·CNtBu, 4a), which can be regarded as the resting state of the system. The reactive species 2a and 3a could be re-generated in situ by irradiation with red light. The results of this study extend our understanding of this new class of molecular switches.
Mild C?F Activation in Perfluorinated Arenes through Photosensitized Insertion of Isonitriles at 350 nm
Weidlich, Frauke,Esumi, Naoto,Chen, Dongyang,Mück-Lichtenfeld, Christian,Zysman-Colman, Eli,Studer, Armido
supporting information, p. 376 - 383 (2019/11/19)
Fluorinated compounds have become important in the fields of agrochemical industry, pharmaceutical chemistry and materials sciences. Accordingly, various methods for their preparation have been developed in the past. Fluorinated compounds can be accessed via conjugation with fluorinated building blocks, via C?H fluorination or via selective activation of perfluorinated compounds to give the partially fluorinated congeners. Especially the direct activation of C?F bonds, one of the strongest σ-bonds, still remains challenging and new strategies for C?F activation are desirable. Herein a method for the photochemical activation of aromatic C?F bonds is presented. It is shown that isonitriles selectively insert into aromatic C?F bonds while aliphatic C?F bonds remain unaffected. Mechanistic studies reveal the reaction to proceed via the indirect excitation of the isonitrile to its triplet state by photoexcited acetophenone at 350 nm. Due to the relatively mild light used, the process shows high functional group tolerance and various compounds of the class of benzimidoyl fluorides are accessible from aryl isonitriles and commercially available perfluorinated arenes. (Figure presented.).
Crystal structures and spectroscopic characterization of MBr2(CNXyl)n (M = Fe and Co, n = 4; M = Ni, n = 2; Xyl = 2,6-dimethylphenyl), and of formally zero-valent iron as a cocrystal of Fe(CNXyl)5 and Fe2(CNXyl)9
Brennessel, William W.,Kucera, Benjamin E.,Young, Victor G.,Ellis, John E.
, p. 1118 - 1127 (2019/07/24)
Structures and spectroscopic characterization of the divalent complexes cisdibromidotetrakis( 2,6-dimethylphenyl isocyanide)iron(II) dichloromethane 0.771-solvate, [FeBr2(C9H9N)4]-0.771CH2Cl2 or cis-FeBr2(CNXyl)4-0.771CH2Cl2 (Xyl = 2,6-dimethylphenyl), trans-dibromidotetrakis(2,6-dimethylphenyl isocyanide)-iron(II), [FeBr2(C9H9N)4] or trans-FeBr2(CNXyl)4, trans-dibromidotetrakis(2,6-dimethylphenyl isocyanide)cobalt(II), [CoBr2(C9H9N)4] or trans-CoBr2(CNXyl)4, and trans-dibromidobis(2,6-dimethylphenyl isocyanide)nickel(II), [NiBr2(C9H9N)2] or trans-NiBr2(CNXyl)2, are presented. Additionally, crystals grown from a cold diethyl ether solution of zero-valent Fe(CNXyl)5 produced a structure containing a cocrystallization of mononuclear Fe(CNXyl)5 and the previously unknown dinuclear [Fe(CNXyl)3]2(-2-CNXyl)3, namely pentakis(2,6-dimethylphenyl isocyanide)iron(0) tris(-2-2,6-dimethylphenyl isocyanide)bis[tris(2,6-dimethylphenyl isocyanide)iron(0)], [Fe(C9H9N)5][Fe2(C9H9N)9]. The (M)C- N-C(Xyl) angles of the isocyanide ligand are nearly linear for the metals in the +2 oxidation state, for which the ligands function essentially as pure donors. The -CN stretching frequencies for these divalent metal isocyanides are at or above that of the free ligand. Relative to FeII, in the structure containing iron in the formally zero-valent oxidation state, the Fe-C bond lengths have shortened, the C N bond lengths have elongated, the (M)C-N-C(Xyl) angles of the terminal CNXyl ligands are more bent, and the -CN stretching frequencies have shifted to lower energies, all indicative of substantial M(d-).- backbonding.
Magnesium Aldimines Prepared by Addition of Organomagnesium Halides to 2,4,6-Trichlorophenyl Isocyanide: Synthesis of 1,2-Dicarbonyl Derivatives
Schw?rzer, Kuno,Bellan, Andreas,Z?schg, Maximilian,Karaghiosoff, Konstantin,Knochel, Paul
, p. 9415 - 9418 (2019/05/10)
The selective addition of organomagnesium reagents to 2,4,6-trichlorophenyl isocyanide leading to magnesiated aldimines is reported. These aldimines react with Weinreb amides, ketones, or carbonates to provide the corresponding carbonyl derivatives after acidic cleavage. This allows for an efficient synthesis of 1,2-dicarbonyl compounds and α-hydroxy ketones.
Excited-State Switching between Ligand-Centered and Charge Transfer Modulated by Metal-Carbon Bonds in Cyclopentadienyl Iridium Complexes
Deaton, Joseph C.,Taliaferro, Chelsea M.,Pitman, Catherine L.,Czerwieniec, Rafa?,Jakubikova, Elena,Miller, Alexander J. M.,Castellano, Felix N.
, p. 15445 - 15461 (2019/01/04)
Three series of pentamethylcyclopentadienyl (Cp?) Ir(III) complexes with different bidentate ligands were synthesized and structurally characterized, [Cp?Ir(tpy)L]n+ (tpy = 2-tolylpyridinato; n = 0 or 1), [Cp?Ir(piq)L]n+ (piq = 1-phenylisoquinolinato; n = 0 or 1), and [Cp?Ir(bpy)L]m+ (bpy = 2,2′-bipyridine; m = 1 or 2), featuring a range of monodentate carbon-donor ligands within each series [L = 2,6-dimethylphenylisocyanide; 3,5-dimethylimidazol-2-ylidene (NHC); methyl)]. The spectroscopic and photophysical properties of these molecules and those of the photocatalyst [Cp?Ir(bpy)H]+ were examined to establish electronic structure-photophysical property relationships that engender productive photochemical reactivity of this hydride and its methyl analogue. The Ir(III) chromophores containing ancillary CNAr ligands exhibited features anticipated for predominantly ligand-centered (LC) excited states, and analogues bearing the NHC ancillary exhibited properties consistent with LC excited states containing a small admixture of metal-to-ligand charge-transfer (MLCT) character. However, the molecules featuring anionic and strongly σ-donating methyl or hydride ligands exhibited photophysical properties consistent with a high degree of CT character. Density functional theory calculations suggest that the lowest energy triplet states in these complexes are composed of a mixture of MLCT and ligand-to-ligand CT originating from both the Cp? and methyl or hydride ancillary ligands. The high degree of CT character in the triplet excited states of methyliridium complexes bearing C^N-cyclometalated ligands offer a striking contrast to the photophysical properties of pseudo-octahedral structures fac-Ir(C^N)3 or Ir(C^N)2(acac) that have lowest-energy triplet excited states characterized as primarily LC character with a more moderate MLCT admixture.
Palladium-Catalyzed One-Pot Synthesis of N -Sulfonyl, N -Phosphoryl, and N -Acyl Guanidines
Qiao, Guanyu,Zhang, Zhen,Huang, Baoliang,Zhu, Liu,Xiao, Fan,Zhang, Zhenhua
supporting information, p. 330 - 340 (2018/01/12)
An efficient palladium-catalyzed cascade reaction of azides with isonitrile and amines is presented; it offers an alternative facile approach toward N -sulfonyl-, N -phosphoryl-, and N -acyl-functionalized guanidines in excellent yield. These series of substituted guanidines exhibit potential biological and pharmacological activities. In addition, the less reactive intermediate benzoyl carbodiimide could be isolated by silica gel column flash chromatography in moderate yield.
TEMPO-Catalyzed Aerobic Oxidative Selenium Insertion Reaction: Synthesis of 3-Selenylindole Derivatives by Multicomponent Reaction of Isocyanides, Selenium Powder, Amines, and Indoles under Transition-Metal-Free Conditions
Liu, Huan,Fang, Yi,Wang, Shun-Yi,Ji, Shun-Jun
supporting information, p. 930 - 933 (2018/02/22)
A novel and efficient approach for the selenium functionalization of indoles was developed with selenium powder as the selenium source, catalyzed by 2,2,6,6-tetramethylpiperidinooxy (TEMPO) and employing O2 as the green oxidant. This protocol provides a practical route for the synthesis of 3-selenylindole derivatives and has the advantages of readily available starting materials, mild reaction conditions, and a wide scope of substrates. Electron spin-resonance (ESR) studies reveal that the approach involves the formation of nitrogen-centered radicals and selenium radicals via oxidation of in situ generated selenoates.
Hexafluoroisopropanol as the Acid Component in the Passerini Reaction: One-Pot Access to β-Amino Alcohols
Saya, Jordy M.,Berabez, Rayan,Broersen, Pim,Schuringa, Imme,Kruithof, Art,Orru, Romano V. A.,Ruijter, Eelco
supporting information, p. 3988 - 3991 (2018/07/15)
A new Passerini-type reaction in which hexafluoroisopropanol functions as the acid component is reported. The reaction tolerates a broad range of isocyanides and aldehydes, and the formed imidates can be reduced toward β-amino alcohols under mild and metal-free conditions. In addition, the imidate products were shown to undergo an unprecedented retro-Passerini-type reaction under microwave conditions, providing valuable mechanistic information about the Passerini reaction and its variations.
