86610-63-1Relevant academic research and scientific papers
Photocatalyzed Diastereoselective Isomerization of Cinnamyl Chlorides to Cyclopropanes
Dykstra, Ryan,Gutierrez, Osvaldo,Martin, Robert T.,Tambar, Uttam K.,Troian-Gautier, Ludovic,Xu, Bin
supporting information, p. 6206 - 6215 (2020/04/27)
Endergonic isomerizations are thermodynamically unfavored processes that are difficult to realize under thermal conditions. We report a photocatalytic and diastereoselective isomerization of acyclic cinnamyl chlorides to strained cyclopropanes. Quantum mechanical calculations (uM06-2X and DLPNO), including TD-DFT calculations, and experimental studies provide evidence for the energy transfer from an iridium photocatalyst to the allylic chloride substrate followed by C-Cl homolytic cleavage. Subsequent Cla￠ radical migration forms a localized triplet 1,3-diradical intermediate that, after intersystem crossing, undergoes ring-closing to form the desired product. The mild reaction conditions are compatible with a broad range of functional groups to generate chlorocyclopropanes in high yields and diastereoselectivities. A more efficient process is developed by addition of a catalytic amount of a nickel complex, and we propose a novel role for this cocatalyst to recycle an allyl chloride byproduct generated in the course of the reaction. The reaction is also shown to be stereoconvergent, as an E/Z mixture of cinnamyl chlorides furnish the anti-chlorocyclopropane product in high diastereoselectivity. We anticipate that the use of a visible light activated photocatalyst to transform substrates in combination with a transition metal catalyst to recycle byproducts back into the catalytic cycle will provide unique opportunities for the discovery of new reactivity.
Pyrazolopyrimidine Ribonucleosides as Anticoccidials. 3. Synthesis and Activity of Some Nucleosides of 4-pyrazolopyrimidines
Rideout, Janet L.,Krenitsky, Thomas A.,Chao, Esther Y.,Elion, Gertrude B.,Williams, Raymond B.,Latter, Victoria S.
, p. 1489 - 1494 (2007/10/02)
Ribonucleosides of 4-(alkylthio)-1H-pyrazolopyrimidines have been shown to be useful anticoccidial agents .In that study, the unsaturated 4-allylthio and 4-crotylthio derivatives (19 and 20) were shown to be more active in vivo against Eimeria tenella than their saturated congeners; therefore, some unsaturated (arylalkyl)thio derivatives were synthesized and investigated as anticoccidial agents.The novel compounds in this study (2 to 18) were prepared by the alkylation of 4-mercapto-1-β-D-ribofuranosyl-1H-pyrazolopyrimidine (1), which was prepared by an enzymatic method.The (E)-4-cinnamylthio derivative (2) and the 5'-monophosphate (18) were the most active compounds against E. tenella in vivo.None of the analogues with substituents in the aryl moiety (3 to 13) was more active than 2 in vivo.The geometry about the double bond was important, since the (Z)-4-cinnamylthio derivative (14) was inactive both in vitro and in vivo.The 4-(3-phenylpropynyl)thio and 4-(5-phenyl-2,4-pentadienyl)thio derivatives (15 and 16) were at least as active as 2 in vitro; however, they were less active than 2 in vivo.Compound 2 was effective in vivo against E. tenella, E. necatrix, E. maxima, and E. brunetti; these species of Eimeria were controlled when 2 was given in the diet at levels up to 100 ppm.Infections in vivo due to E. acervulina were controlled by 2 only at about 800 ppm.The broad spectrum of anticoccidial activity shown by 2 represents a significant improvement over the activities reported for related compounds .
