186704-03-0Relevant academic research and scientific papers
Electrochemical Dearomative Dicarboxylation of Heterocycles with Highly Negative Reduction Potentials
Hayashi, Hiroki,Kanna, Wataru,Maeda, Satoshi,Mita, Tsuyoshi,Takano, Hideaki,You, Yong
supporting information, p. 3685 - 3695 (2022/03/08)
The dearomative dicarboxylation of stable heteroaromatics using CO2is highly challenging but represents a very powerful method for producing synthetically useful dicarboxylic acids, which can potentially be employed as intermediates of biologically active molecules such as natural products and drug leads. However, these types of transformations are still underdeveloped, and concise methodologies with high efficiency (e.g., high yield and high selectivity for dicarboxylations) have not been reported. We herein describe a new electrochemical protocol using the CO2radical anion (E1/2of CO2= -2.2 V in DMF and -2.3 V in CH3CN vs SCE) that produces unprecedented trans-oriented 2,3-dicarboxylic acids from N-Ac-, Boc-, and Ph-protected indoles that exhibit highly negative reduction potentials (-2.50 to -2.94 V). On the basis of the calculated reduction potentials, N-protected indoles with reduction potentials up to -3 V smoothly undergo the desired dicarboxylation. Other heteroaromatics, including benzofuran, benzothiophene, electron-deficient furans, thiophenes, 1,3-diphenylisobenzofuran, and N-Boc-pyrazole, also exhibit reduction potentials more positive than -3 V and served as effective substrates for such dicarboxylations. The dicarboxylated products thus obtained can be derivatized into useful synthetic intermediates for biologically active compounds in few steps. We also show how the dearomative monocarboxylation can be achieved selectively by choice of the electrolyte, solvent, and protic additive; this strategy was then applied to the synthesis of an octahydroindole-2-carboxylic acid (Oic) derivative, which is a useful proline analogue.
Formal Fluorinative Ring Opening of 2-Benzoylpyrrolidines Utilizing [1,2]-Phospha-Brook Rearrangement for Synthesis of 2-Aryl-3-fluoropiperidines
Kondoh, Azusa,Ojima, Rihaku,Terada, Masahiro
supporting information, p. 7894 - 7899 (2021/10/20)
A ring expansion of 2-benzoylpyrrolidines, which involves the formal fluorinative ring opening utilizing the [1,2]-phospha-Brook rearrangement under Br?nsted base catalysis and a subsequent intramolecular reductive amination, was developed. The operationally simple three-step protocol provides an efficient access to 2-aryl-3-fluoropiperidines. The methodology was further applied to the syntheses of azepanes and tetrahydroquinolines.
Hexafluoroisopropanol: A powerful solvent for the hydrogenation of indole derivatives. Selective access to tetrahydroindoles or cis-fused octahydroindoles
Clarisse, Damien,Fenet, Bernard,Fache, Fabienne
experimental part, p. 6587 - 6594 (2012/09/08)
Pd/C in HFIP was used to hydrogenate indole derivatives under relatively mild conditions, leading to potential synthetic intermediates of bioactive compounds. Depending on their substitution, tetrahydroindoles or octahydroindoles could selectively be obtained.
Orthogonal synthesis of indolines and isoquinolines via aryne annulation
Gilmore, Christopher D.,Allan, Kevin M.,Stoltz, Brian M.
, p. 1558 - 1559 (2008/09/17)
Described in this report is the development of two unique methodologies exploiting the reactivity of arynes. Reaction of N-carbamoyl-functionalized enamine derivatives with benzyne affords substituted indolines. An orthogonal reactivity is uncovered when related enamine derivatives are modified as amides, such that isoquinolines are formed as the product of condensation with benzyne. This latter transformation is applied to a concise total synthesis of the opiate alkaloid papaverine. Copyright
Palladium-catalyzed reduction of N-(tert-Butoxycarbonyl)indoles by polymethylhydrosiloxane
Chandrasekhar, Srivari,Basu, Debjit,Reddy, Ch. Raji
, p. 1509 - 1512 (2008/02/05)
The palladium-catalyzed [10% Pd(OH)2/C] reduction of N-(tert-butoxycarbonyl)indoles to the corresponding N-(tert-butoxycarbonyl) indolines is described. Polymethylhydrosiloxane was used as reducing agent and the reaction proceeded smoothly at r
Both enantiomers of N-Boc-indoline-2-carboxylic esters
Kurokawa, Masayuki,Sugai, Takeshi
, p. 1021 - 1025 (2007/10/03)
An immobilized form of Candida antarctica lipase (Chirazyme L-2) catalyzed enantioselective hydrolysis (E > 1000) of N-Boc-indoline-2-carboxylic acid methyl ester. The reaction proceeded efficiently at 60 °C, a temperature over the melting point of substrate, in the conversion of 49.9% to provide the hydrolyzed product, (S)-carboxylic acid with >99.9% ee and the unreacted (R)-ester with 99.6% ee. A newly developed expeditious route to the racemic substrate (a total of six steps, 60% yield), starting from aniline and ethyl α-methylacetoacetate, established the scalable chemoenzymatic synthesis of the desired compounds in both enantiomerically pure forms.
Hydrogenation of five-membered heteroaromatic compounds catalyzed by a rhodium-phosphine complex
Kuwano, Ryoichi,Sato, Koji,Ito, Yoshihiko
, p. 428 - 429 (2007/10/03)
The rhodium complex generated in situ from Rh(acac)(cod) and 2 equivalents of triphenylphosphine is an effective catalyst for hydrogenation of various five-membered heteroaromatic compounds.
