830-99-9Relevant academic research and scientific papers
A catalytic system for the activation of diorganozinc reagents
Werner, Thomas,Bauer, Matthias,Riahi, Abdol Majid,Schramm, Heiko
, p. 4876 - 4883 (2014/08/05)
We report a novel catalytic system for the activation of diorganozinc reagents. We assumed that the nucleophilic activation of diethylzinc should be efficiently performed by simple alkali metal salts. Indeed, the combination of sodium salts and 15-crown-5 significantly accelerates the rate of diethylzinc addition to benzaldehyde under mild conditions. The activity of the catalytic system strongly depends on the nature of the anion, decreasing in the order I->Br->Cl->F-. Under the optimized reaction conditions, various aryl, hetero aryl, and aliphatic aldehydes were converted with diethylzinc and the corresponding product was obtained in excellent yields. The first X-ray absorption spectroscopy measurements on such type of reactions provide initial insights that support the proposed catalytic cycle and suggest the formation of a zincate complex.
Phosphonium salt catalyzed addition of diethylzinc to aldehydes
Werner, Thomas,Riahi, Abdol Majid,Schramm, Heiko
experimental part, p. 3482 - 3490 (2011/12/04)
The addition of diethylzinc to aromatic, heteroaromatic, and aliphatic aldehydes at room temperature is efficiently catalyzed by 1-7 mol% tetrabutylphosphonium chloride. The corresponding addition products are obtained in good to excellent yields of up to 99%. Moreover, polymer bond phosphonium salts can be used to catalyze this reaction with excellent recovery of the polymer bond catalyst up to three cycles. The application of chiral bifunctional phosphonium salts revealed a remarkable counter anion effect. Changing the anion, the activity of the tetrabutylphosphonium salt decreased in the order Cl- > Br- > I- ≈ TsO- > BF4- ≈ PF6-. However, the nature of the cation had also significant influence. Tetraalkyl-ammonium chlorides showed similar activity compared to phosphonium chlorides, while alkaline metal chlorides proved to be considerably less active. Georg Thieme Verlag Stuttgart.
Unexpected formation of aryl dialkyl carbinol as a side product from the reaction of methoxyarylaldehydes with Grignard reagents
Sharma, Anuj,Joshi, Bhupendra P.,Singh, Narendra P.,Sinha, Arun K.
, p. 847 - 851 (2007/10/03)
In the attempted formation of secondary aryl alkyl carbinols from the reaction of methoxyarylaldehydes with Grignard reagents, aryl dialkyl carbinols were formed as unexpected side products. A mechanism for their formation is proposed.
Stereoselective syntheses of substituted pterocarpans with anti-HIV activity, and 5-aza-/5-thia-pterocarpan and 2-aryl-2,3-dihydrobenzofuran analogues
Engler, Thomas A.,LaTessa, Kenneth O.,Iyengar, Rajesh,Chai, Wenying,Agrios, Konstantinos
, p. 1755 - 1769 (2007/10/03)
Oxygenated pterocarpans and 5-azapterocarpans are prepared utilizing Lewis acid-promoted reactions of 2-alkoxy-1,4-benzoquinones with 2H-chromenes and N-tosyl-1,2-dihydroquinolines, respectively. Similarly, benzannulated analogues are prepared via reactions of 5-aIkoxy-1,4-naphthoquinones with chromenes, and related 2-aryl-2,3-dihydrobenzofurans result from reactions of styrenes with the quinones. Syntheses of 5-thiapterocarpans are also described utilizing Pd(0)-coupling of o-chloromercuriophenols with 2H-chromenes.
Ring-Substituted 1,2-Dialkylated 1,2-Bis(hydroxyphenyl)ethanes. 1. Synthesis and Estrogen Receptor Binding Affinity of 2,2'-and 3,3'-Disubstituted Hexestrols
Hartmann, Rolf W.,Schwarz, Walter,Schoenenberger, Helmut
, p. 1137 - 1144 (2007/10/02)
The syntheses of symmetrically 3,3'- and 2,2'-disubstituted meso hexestrol derivatives are described 3,3'-substituents: OH (1), F (2), Cl (3), Br (4), I (5), CH2N(CH3)2 (6), CH3 (7), CH2OCH3 (8), CH2OC2H5 (9), CH2OH (10), NO2 (11), NH2 (12) N(CH3)2 (13),
