- C2-Selective C-H methylation of heterocyclic N-oxides with sulfonium ylides
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A redox-neutral C2-selective methylation of heterocyclic N-oxides with sulfonium ylides is described herein. This report presents unprecedented findings for the utility of sulfonium ylides as the methylation source of N-heterocycles beyond the Corey-Chaykovsky reaction. Intriguingly, pyrrolidine plays a significant role in minimizing the reductive C2-methylation process. This method is characterized by its mild conditions, simplicity, and excellent site selectivity. The applicability of the developed protocol is showcased by the late-stage methylation and sequential transformations of complex drug molecules.
- An, Won,Choi, Su Bin,Kim, Namhoon,Kwon, Na Yeon,Ghosh, Prithwish,Han, Sang Hoon,Mishra, Neeraj Kumar,Han, Sangil,Hong, Sungwoo,Kim, In Su
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supporting information
p. 9004 - 9009
(2020/11/30)
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- Cathode Material Determines Product Selectivity for Electrochemical C?H Functionalization of Biaryl Ketoximes
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The synthesis of polycyclic N-heteroaromatic compounds and their corresponding N-oxides has been developed through electrochemical C?H functionalization of biaryl ketoximes. The oxime substrates undergo dehydrogenative cyclization when a Pt cathode is used, resulting in unprecedented access to a wide range of N-heteroaromatic N-oxides. The products of the electrosynthesis are switched to the deoxygenated N-heteroaromatics by employing a Pb cathode through sequential anode-promoted dehydrogenative cyclization and cathodic cleavage of the N?O bond in the initially formed N-oxide.
- Zhao, Huai-Bo,Xu, Pin,Song, Jinshuai,Xu, Hai-Chao
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supporting information
p. 15153 - 15156
(2018/10/31)
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- Three component reaction of aryl diazonium salt with sulfonamide & actonitrile to synthesize N-sulfonyl amidine
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A new method was developed to prepare N-sulfonyl amidine compounds through three-component reaction of aryl diazonium salts with sulfonamides and acetonitrile, in which, nitrilium ion intermediate, generated from the reaction of aryldiazonium salt with nitrile, was subsequently trapped by sulfonamides. A series of N-sulfonyl amidine derivatives were synthesized by using various types of aryl diazonium salts, sulfonamides and nitriles. In addition, indolyl imine products could also be prepared by using indole as the nucleophile to trap nitrilium ion intermediate.
- Zhang, Yuan,Chen, Zili
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supporting information
p. 4183 - 4186
(2018/10/24)
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- Pd-catalyzed assembly of phenanthridines from aryl ketone O-acetyloximes and arynes through C-H bond activation
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Pd-catalyzed annulation of aryne and aryl ketone O-acetyloxime via C-H bond activation was realized. Through the C-H bond activation/insertion/cyclization/ elimination reaction sequence, phenanthridines are successfully constructed, providing an attractiv
- Tang, Chen-Yu,Wu, Xin-Yan,Sha, Feng,Zhang, Fei,Li, Hao
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supporting information
p. 1036 - 1039
(2014/02/14)
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- Pd-catalyzed assembly of phenanthridines from aryl ketone O-acetyloximes and arynes through C-H bond activation
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Pd-catalyzed annulation of aryne and aryl ketone O-acetyloxime via C-H bond activation was realized. Through the C-H bond activation/insertion/cyclization/elimination reaction sequence, phenanthridines are successfully constructed, providing an attractive
- Tang, Chen-Yu,Wu, Xin-Yan,Sha, Feng,Zhang, Fei,Li, Hao
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supporting information
p. 1036 - 1039
(2015/02/19)
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- Di-tert butyl peroxide-promoted sequential methylation and intramolecular aromatization of isonitriles
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The di-tert butyl peroxide (DTBP)-promoted sequential reaction of isonitriles is developed, leading to 6-methylphenanthridine derivatives in moderate to excellent yields. DTBP served as both promoter and methyl source. The procedure proceeds through the addition of a methyl radical derived from the peroxide to the isonitrile followed by aromatic homolytic cyclization. It tolerates a series of functional groups, such as fluoro, chloro, acetyl, methoxycarbonyl, cyano and trifluoromethyl.
- Dai, Qiang,Yu, Jin-Tao,Feng, Xiaomei,Jiang, Yan,Yang, Haitao,Cheng, Jiang
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supporting information
p. 3341 - 3346
(2015/01/09)
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- Dioxime oxalates; new iminyl radical precursors for syntheses of N-heterocycles
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Symmetrical and unsymmetrical dioxime oxalates were prepared by treatment of oximes with oxalyl chloride. UV photolysis of these precursors was found to be an atom-efficient way of generating iminyl radicals. The process was most efficient for dioxime oxalates having aryl substituents attached to their C{double bond, long}N bonds. The method was useful for EPR spectroscopic study of iminyl and iminoxyl radicals. Photolyses in toluene solution, of dioxime oxalates containing alkenyl acceptor groups, yielded unsaturated iminyl radicals that ring closed to afford 3,4-dihydro-2H-pyrroles in good yields. Dioxime oxalates with biphenyl substituents also released iminyl radicals that ring closed onto the aromatic acceptor groups and, in acetonitrile solution, this approach provided a useful and atom-efficient method of making substituted phenanthridines.
- Portela-Cubillo, Fernando,Lymer, James,Scanlan, Eoin M.,Scott, Jackie S.,Walton, John C.
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scheme or table
p. 11908 - 11916
(2009/04/06)
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- Different behavior of nitrenes and carbenes on photolysis and thermolysis: Formation of azirine, ylidic cumulene, and cyclic ketenimine and the rearrangement of 6-phenanthridylcarbene to 9-phenanthrylnitrene
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Flash vacuum thermolysis (FVT) of 9-azidophenanthrene 8, 6-(5-tetrazolyl)phenanthridine 18, and [1,2,3]triazolo[l,5-f]phenanthridine 19 yields 9-cyanofluorene 12 as the principal product and 4-cyanofluorene as a minor product. In all cases, when the product is condensed at or below 77 K, the seven-membered ring ketenimine 24 is detectable by IR spectroscopy (1932 cm-1) up to 200 K. Photolysis of Ar matrix isolated 8 at λ = 308 or 313 nm generates at first the azirine 26, rapidly followed by the ylidic cumulene 27. The latter reverts to azirine 26 at λ > 405 nm, and the azirine reverts to the ylidic cumulene at 313 nm. Nitrene 9 is observed by ESR spectroscopy following FVT of either azide 8, tetrazole 18, or triazole 19 with Ar matrix isolation of the products. Nitrene 9 and carbene 21 are observed by ESR spectroscopy in the Ar matrix photolyses of azide 8 and triazole 19, respectively.
- Kvaskoff, David,Bednarek, Pawel,George, Lisa,Pankajakshan, Sreekumar,Wentrup, Curt
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p. 7947 - 7955
(2007/10/03)
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- Thermal decomposition of tert-butyl ortho-(phenylsulfanyl)- and ortho-(phenylsulfonyl)phenyliminoxyperacetates: The reactivity of thio-substituted iminyl radicals
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Some ortho-(phenylsulfanyl)- and ortho-(phenylsulfonyl)-substituted phenyliminyl radicals have been generated by thermal decomposition of suitable tert-butyl iminoxyperacetates. The sulfanyl-substituted iminyls showed no tendency to give either 1,7- or 1,
- Leardini,McNab,Minozzi,Nanni
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p. 1072 - 1078
(2007/10/03)
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- ν-triazolines. Part 40. Thermal and photochemical transformations of 1-biaryl-5-amino-4,5-dihydro-ν-triazoles: A new synthetic approach to 6-alkylphenanthridines and aza-analogs
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1-Biaryl-5-morpholino-ν-triazolines 4 were prepared from aliphatic aldehydes 1, morpholine and 2-azidobiaryls 3. They underwent smooth thermal rearrangement to tertiary amidines 5 which were photochemically cyclized to 6-alkylphenanthridines 6a,b,e,f and analogs 6c,d and 8a,b with morpholine elimination. Direct photolysis of triazolines 4 afforded lower yields of the same compounds 6 together with by-products indicative of the mechanism of the photochemical rearrangement which is discussed.
- Erba, Emanuela,Pocar, Donato,Trimarco, Pasqualina
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p. 3535 - 3539
(2007/10/03)
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- PHOTOLYTIC GENERATION OF KETONES FROM 6-PHENANTHRIDINYLMETHYL ETHERS OF SECONDARY ALCOHOLS
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Ketones are generated by photolysis (>320 nm) of 6-phenanthridinylmethyl ethers of secondary alcohols.The 6-phenanthridinylmethyl group may therefore be utilized as a latent carbonyl function, especially as the 6-phenanthridinyl-methyl group is chemically inert toward hydroboration, Grignard additions, LiAlH4-reduction, bromination or ozonolysis at other parts of the molecule.
- Rukachaisirikul, Vatcharin,Hoffmann, Reinhard W.
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p. 10563 - 10568
(2007/10/02)
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- Intramolecular Cyclization of Iminoxyl Radicals
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Iminyl radicals, generated by oxidation of the corresponding O-carboxymethoximes with persulfate, do not cyclise onto an ajacent azo group but the structurally related iminoxyls cyclise to give indazoles.ESR evidence is presented for the intramolecular ad
- Atmaram, Shiravanate,Forrester, Alexander R.,Gill, Melvyn,Napier, Russell J.,Thomson, Ronald H.
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p. 641 - 648
(2007/10/02)
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