- Sequential Carbon-Carbon/Carbon-Selenium Bond Formation Mediated by Iron(III) Chloride and Diorganyl Diselenides: Synthesis and Reactivity of 2-Organoselenyl-Naphthalenes
-
In this paper, we report an intramolecular cyclization of benzylic-substituted propargyl alcohols promoted by iron(III) chloride and diorganyl diselenides to give 2-organoselenyl-naphthalenes via a sequential carbon-carbon/carbon-selenium bond formation. The present reaction tolerated a wide range of substituents in both propargyl alcohols and diorganyl diselenides to give the desired 2-organoselenyl-naphthalenes in good yields with high selectivity. In addition, O-acyl protected propargyl alcohol and propargyl bromide were also subjected to this protocol giving the corresponding 2-organoselenyl-naphthalenes. We found that dichalcogenide species affected the formation of cyclized products, whereas diorganyl diselenides gave high yields, moderate yields were obtained with diorganyl disulfides, and no product formation was found with diorganyl ditellurides. The key transformations could be attributed to the carbon-carbon triple bond activation of benzylic-substituted propargyl alcohols by a seleniranium ion, antiattack of the electron cloud from the aromatic ring at the activated triple bond, and cyclization via an exclusive 6-endo-dig process. We also found that the corresponding 2-organoselenyl-naphthalenes are suitable substrates to the selenium-lithium exchange reactions followed by trapping with aldehydes affording the corresponding secondary alcohols.
- Recchi, Ana M. S.,Back, Davi F.,Zeni, Gilson
-
-
Read Online
- COMPOUND, MATERIAL FOR ORGANIC ELECTROLUMINESCENT ELEMENT, ORGANIC ELECTROLUMINESCENT ELEMENT, AND ELECTRONIC DEVICE
-
PROBLEM TO BE SOLVED: To provide an organic electroluminescent element with high performance and a novel material for achieving organic electroluminescent element. SOLUTION: There is provided a compound represented by the formula (1). In the formula (1),
- -
-
Paragraph 0125-0126
(2020/01/23)
-
- Scalable, Stereocontrolled Formal Syntheses of (+)-Isoschizandrin and (+)-Steganone: Development and Applications of Palladium(II)-Catalyzed Atroposelective C?H Alkynylation
-
Dibenzocyclooctadiene lignans are an interesting class of molecules because of their unique structure based on an axially chiral biaryl moiety as well as their significant biological activity. Herein, we describe the development of a palladium-catalyzed atroposelective C?H alkynylation and its application in gram-scale, stereocontrolled formal syntheses of (+)-isoschizandrin and (+)-steganone. tert-Leucine was identified as an efficient, catalytic transient chiral auxiliary. A wide range of enantiomerically enriched biaryl compounds were prepared by this approach in good yields (up to 99 %) with excellent enantioselectivity (up to >99 % ee).
- Liao, Gang,Yao, Qi-Jun,Zhang, Zhuo-Zhuo,Wu, Yong-Jie,Huang, Dan-Ying,Shi, Bing-Feng
-
supporting information
p. 3661 - 3665
(2018/03/05)
-
- Ruthenium(0)-Catalyzed C-H Arylation of Aromatic Imines under Neutral Conditions: Access to Biaryl Aldehydes
-
The first ruthenium(0)-catalyzed C-H bond arylation of aromatic imines with arylboronates under neutral conditions is reported. This versatile method provides rapid access to a wide range of biaryl aldehydes that are difficult to assemble using traditional methods with high atom economy. A new hydrogen acceptor for Ru(0) arylation has been identified. This atom-economical strategy has potential for an array of direct applications in Ru(0)-catalyzed C-H bond arylations using removable directing groups. An indole synthesis by a sequential one-pot, multiple C-H activation protocol is reported.
- Hu, Feng,Szostak, Michal
-
p. 4186 - 4189
(2016/09/09)
-
- Gold-catalyzed 6-exo-dig cycloisomerization: A versatile approach to functionalized phenanthrenes
-
A novel gold-catalyzed 6-exo-dig cycloisomerization of o-propargylbiaryls has been developed that provides ready access to functionalized phenanthrenes in largely good to excellent yields. Notable features of this method are readily available starting materials, mild reaction conditions, and broad substrate scope. Golden cat: A novel gold-catalyzed 6-exo-dig cycloisomerization of o-propargylbiaryls has been developed that provides ready access to functionalized phenanthrenes in largely good to excellent yields. Notable features of this method are readily available starting materials, mild reaction conditions, and broad substrate scope.
- Shu, Chao,Li, Long,Chen, Cheng-Bin,Shen, Hong-Cheng,Ye, Long-Wu
-
supporting information
p. 1525 - 1529
(2014/06/09)
-
- Copper-catalyzed synthesis of phenanthridine derivatives under an oxygen atmosphere starting from biaryl-2-carbonitriles and grignard reagents
-
A copper-catalyzed synthesis of phenanthridine derivatives was developed starting from biaryl-2-carbonitriles and Grignard reagents. The present transformation is carried out by a sequence of nucleophilic addition of Grignard reagents to biaryl-2-carbonitriles to form N-H imines and their Cu-catalyzed C-N bond formation on the aromatic C-H bond, where molecular oxygen is a prerequisite to achieve the catalytic process.
- Zhang, Line,Ang, Gim Yean,Chiba, Shunsuke
-
supporting information; experimental part
p. 3682 - 3685
(2010/10/20)
-
- NOVEL CURCUMIN DERIVATIVE
-
The present invention provides a novel compound that is structurally similar to curcumin and has a suppressive effect on Aβ aggregation, a degradative effect on Aβ aggregates, an inhibitory effect on β-secretase, and a protective effect on neurons. The novel compound is a compound represented by the following general formula (Ia) or a salt thereof: wherein R1 represents a 4-hydroxy-3-methoxyphenyl group or the like, and R2 represents a 1H-indol-6-yl group or the like.
- -
-
Page/Page column 103
(2009/12/07)
-
- Microwave-assisted syntheses of N-heterocycles using alkenone-, alkynone- and aryl-carbonyl O-phenyl oximes: Formal synthesis of neocryptolepine
-
(Chemical Equation Presented) This research aimed to provide a new and "clean" synthetic method that would enable both known and novel N-heterocycles to be prepared efficiently. O-Phenyl oximes were found to be excellent precursors for iminyl radicals with a variety of acceptor side chains. Dihyropyrroles were made in good yields from O-phenyl oximes containing pent-4-ene acceptors. The analogous process with a hex-5-enyl acceptor did not yield a dihydropyridine, probably because the 6-exo-trig ring closure of the iminyl radical was too slow to compete with H-atom abstraction. The iminyl radical from a precursor with a pent-4-yne type side chain underwent ring closure followed by rearrangement to afford a pyrrole derivative. Suitably substituted iminyl radicals ring closed readily onto aromatic acceptors, thus enabling several polycyclic systems to be accessed. Quinolines were made from 3-phenylpropanones via their O-phenyl oximes. Syntheses of phenanthridines starting from 2-formylbiphenyls were particularly efficient, and this approach enabled the natural product trisphaeridine to be made. Starting from 2-phenylnicotinaldehyde derivatives, ring closures of the derived iminyl radicals onto the phenyl rings yielded benzo[h][1,6]naphthyridines. Similarly, ring closure onto a phenyl ring from a benzothiophene-based iminyl yielded a benzo[b-]thieno[2,3-c]quinoline. By way of contrast, iminyl radical ring closure onto pyridine rings was not observed. However, iminyl radicals did cyclize onto indoles, enabling indolopyridines to be prepared. The latter route was exploited in a short formal synthesis of neocryptolepine starting from 2-((1H-indol-3-yl)methyl)cyclohexanone.
- Portela-Cubillo, Fernando,Scott, Jackie S.,Walton, John C.
-
p. 5558 - 5565
(2008/12/20)
-
- Methodology for the synthesis of 1,2-disubstituted arylnaphthalenes from α-tetralones
-
α-Tetralones were initially converted into 1-bromo- dihydronaphthalene-2-carbaldehydes and 1-bromo-naphthalene-2-carbaldehydes. These precursors were then subjected to Suzuki coupling reactions to afford 1,2-disubstituted aryldihydronaphthalenes and 1,2-disubstituted arylnaphthalenes, respectively. The former products were oxidized with DDQ to give 1,2-disubstituted arylnaphthalenes.
- Moleele, Simon S.,Michael, Joseph P.,De Koning, Charles B.
-
p. 2831 - 2844
(2007/10/03)
-