- Intramolecular carbenoid insertions: Reactions of α-diazo ketones derived from furanyl-, thienyl-, (benzofuranyl)-, and (benzothienyl)acetic acids with rhodium(II) acetate
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α-Diazo ketones tethered to furan, benzofuran, thiophene, and benzothiophene by a single methylene spacer have been shown to undergo atypical, rhodium(II) acetate catalyzed chemistry. For example, while treatment of 1-diazo-3-(3-furanyl)-2-propanone with Rh2(OAc)4 resulted in the expected 2-(4-oxo-2-cyclopentenylidene)acetaldehyde, isomeric 1-diazo-3- (2-furanyl)-2-propanone undergoes a vinylogous Wolff rearrangement and in the presence of water gives a mixture of 6a-methyl-2,3,3a,6a-tetrahydrofuro [2,3- b]furan-2-one and 2-(2-methyl-3-furyl)acetic acid. Rhodium acetate catalyzed decomposition of 1-diazo-3-(3-benzofuranyl)-2-propanone and 1-diazo-3-(2- benzofuranyl)-2-propanone are also shown to undergo vinylogous Wolff rearrangement despite the fact that this chemistry is not observed with homologous benzofuranyl systems. α-Diazo ketones derived from benzothienyl propionic acids undergo the expected cyclization with 1-diazo-4-(3- benzothienyl)-2-butanone and 1-diazo-4-(2-benzothienyl)-2-butanone giving rise to 1,2,3,4-tetrahydrodibenzo[b,d]thiophen-3-one and 1,2,3,4- tetrahydrodibenzo[b,d]thiophen-2-one, respectively. While decomposition of 1- diazo-3(3-benzothienyl)-2-propanone resulted in the formation of 2,3-dihydro- 1H-benzo[b]cyclopenta[d]thiophen-2-one, the isomeric 1-diazo-3-(2- benzothienyl)-2-propanone gave a dimer which resulted from a [3 + 2] cycloaddition followed by a [1,3]-alkyl shift. Overall, the results from this study of intramolecular carbenoid insertion into five-membered heteroaromatic systems show that the resultant chemistry is dependent on the nature of the heteroatom, position of substitution, and the length of the aliphatic tether.
- Yong, Kelvin,Salim, Mohamed,Capretta, Alfredo
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Read Online
- CIBALACKROT RED DYE COMPOUNDS AND METHODS OF USE IN ORGANIC SOLID-STATE LASERS AND OPTO-ELECTRONIC APPLICATIONS
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Cibalackrot red dye monomer and dimer compounds of formulae (I) and (II) are disclosed as well as combination of the Cibalackrots with host matrices such as a mixed host of mCP and HBT. Use of the Cibalackrots as laser dyes as well in organic solid-state lasers and opto-electronic applications is also described.
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Paragraph 00206
(2021/04/10)
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- COMPOSITIONS AND METHODS OF TARGETING MUTANT K-RAS
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Compounds and compositions are presented that inhibit K-ras, and especially mutant K-ras. Certain compounds preferentially or even selectively inhibit specific forms of mutant K-Ras, and particularly the G12D mutant form.
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Paragraph 0112
(2018/04/20)
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- Copper(ii) chloride mediated (aza)oxindole synthesis by oxidative coupling of Csp2-H and Csp3-H centers: Substrate scope and DFT study
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A CuCl2 mediated direct intramolecular oxidative coupling of Csp2-H and Csp3-H centers gives access to 3,3-disubstituted oxindoles containing aromatic, heteroaromatic and alkyl substituents as well as a heteroatom at the quaternary center in good to excellent yields. The reaction is carried out in the presence of NaOtBu and CuCl2 in DMF at 110 °C. The key step of this reaction is the formation of an amidyl radical by one electron oxidation of amide enolate followed by an intramolecular radical cyclization reaction (homolytic aromatic substitution reaction). A detailed DFT study shows that the cyclization of the amidyl radical is the rate-limiting step in the oxindole synthesis, whereas the second single electron transfer (SET) becomes the rate-determining step in the aza-oxindole formation. Computational data are in agreement with the experimentally observed relative reactivity and regioselectivity.
- Dey, Chandan,Larionov, Evgeny,Kuendig, E. Peter
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supporting information
p. 6734 - 6743
(2013/10/01)
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- Facile preparation of protected benzylic and heteroarylmethyl amines via room temperature Curtius rearrangement
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A step-wise, room temperature procedure for acyl azide formation and the subsequent Curtius rearrangement of phenyl and heteroaryl acetic acids is described. We have developed a protocol for room temperature Curtius rearrangement in MeOH or CHCl3 that provides an improvement over standard conditions, avoiding the use of additives or heat. This room temperature optimization of the Curtius rearrangement prevents the formation of side products often observed with benzylic acids, allowing access to a variety of benzylic and heteroarylmethyl amines.
- Leathen, Matthew L.,Peterson, Emily A.
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supporting information; experimental part
p. 2888 - 2891
(2010/06/14)
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- Acetanilide herbicides
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The invention relates to novel acetanilides of the formula (I) STR1 wherein Ar represents phenyl, furyl or thienyl, R1 represents hydrogen, C1-5 -alkyl, C3-6 -cycloalkyl, C3-6 -cycloalkyl-methyl, C3-5 alkenyl, C3-5 -alkynyl, C1-3 -haloalkyl, C3-5 -epoxyalkyl, C1-3 -alkoxy-C1-4 -alkyl, C1-3 -alkylthio-C1-4 -alkyl, C1-3 -alkoxycarbonyl-C1-2 -alkyl, cyano-C1-3 -alkyl, or aralkyl R2 represents hydrogen or C1-3 -alkyl, R3 represents hydrogen or C1-3 -alkyl, X represents halogen, and Y represents iso-propyl, tert-butyl, C1-2 -haloalkyl, C1-2 -haloalkoxy, C1-2 -haloalkylthio or C1-2 -alkylsulfonyl, to processes for their preparation and to their use as herbicides. The invention also relates to novel intermediates and to processes for their preparation.
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- Intramolecular Cyclopropanation Reaction of Furanyl Diazo Ketones
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α-Diazo ketones derived from furanyl- and benzofuranylpropionic acids were prepared, and their rhodium(II) acetate catalyzed behavior was studied.The results are consistent with a mechanism in which the key step involves addition of a keto carbenoid intermediate on to the furanyl ?-bond followed by an electrocyclic ring-opening reaction.In the case of the benzo-substituted furanyl system, the suspected bicyclic intermediate was isolated in high yield and its chemistry was subsequently investigated.The bicyclic ketone derived from 1-diazo-4-(2-benzofuryl)-2-butanone undergoes a novel thermal rearrangement to a benzopyranone derivative.This unexpected transformation can be rationalized in terms of a -cycloreversion reaction to give an ortho-quinoidal intermediate, which undergoes a subsequent electrocyclic ring closure followed by a 1,3-hydrogen shift.Furans with side chains of various lengths containing a diazomethyl keto group were also studied.The cyclization chemistry of the closely related diazothienylalkanone system was investigated and found to give products derived from an analogous intramolecular cyclopropanation reaction.
- Padwa, Albert,Wisnieff, Thomas J.,Walsh, Edward J.
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p. 299 - 308
(2007/10/02)
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