Use of Hine's D Values To Predict the Position of the Equilibrium in the Cope Rearrangement of Multiply Substituted 1,5-Dienes
摘要:
A series of 1,5-dienes (1a-f) were employed to test whether Hine's D values can predict the position of equilibrium in Cope rearrangements. In the cases of the substituent pairs [OCH3, H], [OCH3, CH3], [N(CH3)(2), H], [N(CH3)(2), CH3], and [N(CH3)(2), OCH3], equilibrium constants calculated with Hine's D values gave reasonable agreement with those obtained experimentally. Dienes 1g-i were prepared to test whether reduction of the pi-donating character of a nitrogen substituent (carbamoyl vs dimethylamino) would change the directing ability of the nitrogen group. The aggregate order of directing ability was N(CH3)(2) > OCH3 > EtO(2)CN(CH3) > CH3 > A. Diene 15a, with a more complicated substitution pattern (OCH3 and CH3 versus CH3 and H) not directly amenable to analysis with D values, can be considered to reduce to the case of [OCH3, H]. The experimental K-eq obtained agreed with that expected for the [OCH3, H] pair. Dienes 15c and 16b, designed to test the pairs [CH3, SPh] and [OCH3, SPh], respectively, decomposed under the gas phase conditions of the rearrangement. Attempts to effect rearrangement with Pd(II) catalysis failed.
Ruthenium Porphyrin Catalyzed Tandem Sulfonium/Ammonium Ylide Formation and [2,3]-Sigmatropic Rearrangement. A Concise Synthesis of (±)-Platynecine
作者:Cong-Ying Zhou、Wing-Yiu Yu、Philip Wai Hong Chan、Chi-Ming Che
DOI:10.1021/jo049540v
日期:2004.10.1
allyl sulfides such as crotyl sulfide produced an equimolar mixture of anti- and syn-2-(ethylthio)-3-methyl-4-pentenoic acidethyl ester. The analogous “EDA + N,N-dimethylcrotylamine” reaction afforded a mixture of anti- and syn-2-(N,N-dimethylamino)-3-methyl-4-pentenoic acidethyl esters with a diastereoselectivity of 3:1. The observed catalytic activity of [RuII(TTP)(CO)] for the ylide [2,3]-sigmatropic
Iron(III) Corroles and Porphyrins as Superior Catalysts for the Reactions of Diazoacetates with Nitrogen- or Sulfur-Containing Nucleophilic Substrates: Synthetic Uses and Mechanistic Insights
作者:Iris Aviv、Zeev Gross
DOI:10.1002/chem.200701885
日期:2008.4.28
A thorough mechanistic investigation has been performed on the reactions of primary and secondary amines with diazoacetates, which proceed uniquely quickly and efficiently when catalyzed by iron(III) corroles and porphyrins. Two major differences in relation to other metal-based catalysts are that the iron complexes are not poisoned by excess amine and that metal-carbene intermediates are apparently
Copper-Catalyzed Intermolecular Generation of Ammonium Ylides with Subsequent [2,3]Sigmatropic Rearrangement. Efficient Synthesis of Bifunctional Homoallylamines
The [2,3]sigmatropicrearrangement of allylic ammonium ylides generated by the reaction of N,N-dimethyl-1-alkyl-2-methylallylamines derived from terpene alcohols with diazo compounds in the presenc...
The catalytic effectiveness of ruthenium porphyrins for ylide generation in reactions of ethyl diazoacetate and diisopropyl diazomethylphosphonate with allylic amines, sulfides and iodides is described for the first time. These reactions result mainly in products of the [2,3]-sigmatropicrearrangement of intermediate allylic ylides.
The present invention relates to macrocyclic compounds of formula (I) that are useful as inhibitors of the hepatitis C virus (HCV) NS3 protease, their synthesis, and their use for treating or preventing HCV infections.