- A novel monoalkylation of symmetrical α-diones
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An efficient method has been developed for the synthesis of monoalkylated 1.2-diones by using steric approach control. The dihydropyrazine 2 prepared from 2,3-butanedione and 1,2-diamino-2- methylpropane is selectively deprotonated on the less hindered methyl group to give an anion which is alkylated with alkyl iodides and activated bromides. In situ hydrolysis of the alkylated dihydropyrazines gives monoalkylated diones 4 in good yield.
- Gopal, Damodaragounder,Nadkarni, Durgesh V.,Sayre, Lawrence M.
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- Switching diarylethenes reliably in both directions with visible light
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A diarylethene photoswitch was covalently connected to two small triplet sensitizer moieties in a conjugated and nonconjugated fashion and the photochromic performance of the resulting compounds was investigated. In comparison with the parent diarylethene (without sensitizers) and one featuring saturated linkages, the conjugated photoswitch offers superior fatigue resistance upon visible-light excitation due to effective triplet energy transfer from the biacetyl termini to the diarylethene core. Our design makes it possible to switch diarylethenes with visible light in both directions in a highly efficient and robust fashion based on extending π-conjugation and by-product-free ring-closure via the triplet manifold. Flipping the spin: When biacetyl triplet sensitizers were linked to a dithienylethene core in a conjugated fashion, the photoswitching performance dramatically improved. This design makes it possible to switch diarylethenes with visible light in both directions in a highly efficient and robust fashion.
- Fredrich, Sebastian,G?stl, Robert,Herder, Martin,Grubert, Lutz,Hecht, Stefan
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supporting information
p. 1208 - 1212
(2016/01/20)
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- Oxone-mediated oxidative cleavage of β-keto esters and 1,3-diketones to α-keto esters and 1,2-diketones in aqueous medium
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A versatile and highly efficient method for the direct synthesis of α-keto esters and 1,2-diketones has been developed. This approach utilizes the oxidative cleavage of a variety of β-keto esters and 1,3-diketones mediated by an Oxone/aluminum trichloride system. The simple one-step oxidation reaction proceeded selectively in aqueous media to afford products in high yields, short reaction times, and environmentally benign conditions.
- Stergiou, Anastasios,Bariotaki, Anna,Kalaitzakis, Dimitris,Smonou, Ioulia
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p. 7268 - 7273
(2013/08/15)
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- Novel boronic acid Mannich reactions of α,α-dichloro- and α,α,ω-trichloroaldehydes with arylboronic acids
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A novel variation of the boronic acid Mannich (BAM) reaction is described, in which α,α-dichloro- and α,α,ω- trichloroaldehydes, morpholine, and arylboronic acids are used. During this one-pot reaction in refluxing toluene, 1-phenyl-1-morpholinoalkan-2-ones form in moderate yields. The dichloromethylene group is formally converted into a ketone functionality and as such acts as a masked carbonyl group. Georg Thieme Verlag Stuttgart.
- Stas, Sara,Tehrani, Kourosch Abbaspour
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p. 433 - 441
(2008/01/08)
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