نتایج جستجو برای: activated acetylenes
تعداد نتایج: 222145 فیلتر نتایج به سال:
Palladium-catalyzed aminoalkynylation of electronically unbiased olefins with iodoalkynes is reported. The picolinamide auxiliary enables for the first time syn-selective mono-, di- and trisubstituted alkenes to afford corresponding pyrrolidines in up 97 % yield as single diastereomers. Furthermore, through a C−H activation approach, allows rapid synthesis functionalized olefins, which are suit...
Aqueous Sonogashira cross-coupling reactions of 5-iodopyrimidine or 7-iodo-7-deazaadenine nucleosides with bile acid-derived terminal acetylenes linked via an ester or amide tether gave the corresponding bile acid-nucleoside conjugates. Analogous reactions of halogenated nucleoside triphosphates gave directly bile acid-modified dNTPs. Enzymatic incorporation of these modified nucleotides to DNA...
An efficient and operationally simple synthesis of 7-deuteropyrazolo[1,5-a]pyridine and 7-deutero-1,2,4-triazolo[1,5-a]pyridine derivatives using α-H/D exchange of 1-aminopyridinium cations in basic D2O followed by a 1,3-cycloaddition of acetylenes and nitriles is presented. A high regioselectivity and a high degree of deuterium incorporation were achieved. The procedure was applied for several...
The rates of addition of molecular bromine in acetic acid to a number of acetylenes have been found to follow the general equation d(Br,)/dt = [acetylene](k, [Br,] + k3 [Br212 + k,,[Br,] [Br1) In the absence of bromide ion and at low bromine concentrations (< 2 x M), only the k 2 process is observable. These k 2 values for a series of ring-substituted phenylacetylenes are correlated well with o...
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