نتایج جستجو برای: dialkyl acetylendicarboxylate
تعداد نتایج: 1219 فیلتر نتایج به سال:
An aqueous method for the preparation of N,S-dialkyl thiophosphoramidates is reported. Thiophosphorylation of alkylamines was performed using SPCl(3) in aqueous reaction media, and the resulting thiophosphoramidate-S-anions were S-alkylated with soft electrophiles. Ranges of amines and electrophiles were explored.
An efficient enantioselective synthesis of beta,beta-dialkyl-gamma-substituted pantolactones has been achieved utilizing the cationic [Sc((S,S)-R-pybox)](Cl)(2)(+), R = Ph (9), t-Bu (10), complex in a catalyzed aldol reaction as the key step. The pantolactone derivatives are isolated in high enantiomeric excesses. [reaction: see text]
Palladium-catalyzed methods for intermolecular aerobic oxidative amination of alkenes have been identified that are compatible with the use of alkene as the limiting reagent. These procedures, which enhance the utility of this reaction with alkenes that are not commercially available, are demonstrated with substrates bearing dialkyl ether, carboxyester, epoxide, and silyl ether groups.
Asymmetric addition under mild conditions of dialkyl phosphites on aldimines derived from cinnamaldehyde catalyzed by the inexpensive chiral organocatalyst (R)-3,3'-[4-fluorophenyl](2)-1,1'-binaphthol phosphate has been found effective to give new alpha-amino-phosphonates 9 in moderate yields (30-65%) and enantiomeric excess (8.4%-61.9%).
A Cu-catalyzed [3+2]-type condensation reaction of oxime acetates and dialkyl acetylenedicarboxylates that provides highly substituted pyrroles under aerobic conditions is described. The newly formed pyrroles are easily employed for further transformations to prepare pyrrolo[2,1-a]isoquinoline skeletons.
Treatment of ynol ether-tethered dialkyl acetals with catalytic quantities of scandium triflate in CH(3)CN gives rise to five-, six-, and seven-membered alkoxycycloalkene carboxylates in good to excellent yields. Tri- and tetrasubstituted carbocyclic and heterocyclic alkenes may be formed by this method, and the products obtained may serve as useful intermediates for natural product synthesis.
Enantioselective phosphination and hydrophosphonylation reactions between azomethine imines and diarylphosphine oxides or dialkyl phosphites were respectively developed by the use of a chiral squaramide as the hydrogen bonding organocatalyst, which afforded two types of phosphorus containing product in high yields with good to excellent enantioselectivities.
Hail boration! 2-Dimethylaminopyridine-ligated dihaloborocations [X2B(2-DMAP)](+) with a strained four-membered boracycle were used for the haloboration of terminal and dialkyl internal alkynes (see scheme). Esterification then provided vinyl boronate esters as useful precursors to tetrasubstituted alkenes. Following mechanistic studies, the scope of the haloboration was expanded simply by vari...
The electrochemical behavior of quinoline in anhydrous liquid ammonia was investigated by cyclic voltammetry and controlled potential coulometry. In the absence of added alkylating agent, quinoline is reduced in two steps to yield the radical anion and dianion both of which undergo further chemical reaction. The radical anion species dimerizes to form the dimeric dianion which is stable in the ...
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