- Catalytic Friedel-Crafts Reactions on Saturated Heterocycles and Small Rings for sp3-sp2 Coupling of Medicinally Relevant Fragments
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gem-Diarylheterocycles display a wide range of biological activity. Here we present a systematic study into the formation of 4- to 6-membered O- and N-heterocycles and cyclobutanes bearing the diaryl motif through a catalytic Friedel–Crafts reaction from the corresponding benzylic alcohols. 3,3-Diaryltetrahydrofurans, 4,4-diaryltetrahydropyrans, 3,3-diarylpyrrolidines, 4,4-diaryl-piperidines, as well as diarylcyclobutanes are examined, with results for 3,3-diaryloxetanes and 3,3-diarylazetidines presented for comparison. Three catalytic systems are investigated for each substrate [Ca(II), Li(I) and Fe(III)], across preinstalled aromatic groups of differing electronic character. In most cases examined, the diaryl product is obtained directly from the alcohol with good yields using the most appropriate catalyst system. In the absence of a nucleophile, the olefins from the 5- and 6-membered substrates by elimination of water are obtained under the same reaction conditions.
- Croft, Rosemary A.,Dubois, Maryne A. J.,Boddy, Alexander J.,Denis, Camille,Lazaridou, Anna,Voisin-Chiret, Anne Sophie,Bureau, Ronan,Choi, Chulho,Mousseau, James J.,Bull, James A.
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p. 5385 - 5395
(2019/06/24)
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- Highly enantioselective organocatalytic oxidative kinetic resolution of secondary alcohols using chiral alkoxyamines as precatalysts: Catalyst structure, active species, and substrate scope
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The development and characterization of enantioselective organocatalytic oxidative kinetic resolution (OKR) of racemic secondary alcohols using chiral alkoxyamines as precatalysts are described. A number of chiral alkoxyamines have been synthesized, and their structure-enantioselectivity correlation study in OKR has led us to identify a promising precatalyst, namely, 7-benzyl-3-n-butyl-4-oxa-5-azahomoadamantane, which affords various chiral aliphatic secondary alcohols (ee up to >99%, krel up to 296). In a mechanistic study, chlorine-containing oxoammonium species were identified as the active species generated in situ from the alkoxyamine precatalyst, and it was revealed that the chlorine atom is crucial for high reactivity and enantioselectivity. The present OKR is the first successful example applicable to various unactivated aliphatic secondary alcohols, including heterocyclic alcohols with high enantioselectivity, the synthetic application of which is demonstrated by the synthesis of a bioactive compound.
- Murakami, Keiichi,Sasano, Yusuke,Tomizawa, Masaki,Shibuya, Masatoshi,Kwon, Eunsang,Iwabuchi, Yoshiharu
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p. 17591 - 17600
(2015/02/19)
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- Synthesis of (±)-coerulescine and a formal synthesis of (±)-horsfiline
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A straightforward synthesis of (±)-coerulescine and (±)-horsfiline has been established from 3-formyl-3-phenylpyrrolidine employing 4-hydroxypiperidine as the starting material. There are two remarkable steps for the synthesis of (±)-coerulescine and (±)-horsfiline. One is the rapid access to produce 3-formyl-3-phenylpyrrolidine by Lewis acid-catalyzed rearrangement of 3,4-dihydroxy-4-phenylpiperidine. The other key step is an intramolecular electrophilic cyclization from 3-benzylcarbamoyl-3- phenylpyrrolidine to the 3,3-spirocyclic 2-oxindole ring skeleton.
- Chang, Meng-Yang,Pai, Chun-Li,Kung, Yung-Hua
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p. 8463 - 8465
(2007/10/03)
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- A versatile synthesis of 4-aryl tetrahydropyridines via palladium mediated Suzuki cross-coupling with cyclic vinyl boronates
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A simple preparation of cyclic vinyl boronates derived from the vinyl triflates of N-protected tetrahydropyridines is described. Suzuki coupling of the boronates with aryl bromides, iodides and triflates proceeds in good yield to give 4-aryl tetrahydropyridines. (C) 2000 Elsevier Science Ltd.
- Eastwood, Paul R.
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p. 3705 - 3708
(2007/10/03)
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- Aryl substituted heterocycles
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The present invention concerns the novel use of aryl substituted heterocycles of formula I, set out below, which antagonize the pharmacological actions of one of ent endogenous neuropeptide tachykinins an the neurokinin 2 (NK2) receptor making them useful whenever such antagonism is desired, such as in the treatment of asthma and related conditions. The invention also provides pharmaceutical compositions containing the aryl substituted heterocycles for use in such treatment. Certain novel aryl substituted heterocycles of formula I and novel intermediates for their manufacture are also provided. STR1
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