Arthur Han

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Transition-metal hydrides generate α-alkoxy radicals by H• transfer to enol ethers. We have measured the rate constant for transfer from CpCr(CO)3H to n-butyl vinyl ether and have examined the chemistry of radicals generated by such transfers. Radicals from appropriate substrates undergo 5-exo cyclization, with higher diastereoselectivity than the analogous(More)
We present a new method of rapid sequence-selective microRNA (miRNA) detection with small amount of sample using power-free PDMS microfluidic device and gold-nanoparticles (GNPs). Target miRNA hybridized to probe DNA was labeled by DNA-coated GNPs, which also act as signal amplifiers. This method allows us to detect miRNA of certain sequence in 30 min with(More)
(+)-Ryanodine is a natural product modulator of ryanodine receptors, important intracellular calcium ion channels that play a critical role in signal transduction leading to muscle movement and synaptic transmission. Chemical derivatization of (+)-ryanodine has demonstrated that certain peripheral structural modifications can alter its pharmacology, and(More)
Rate constants have been calculated, and compared with experimental results, for the cyclizations of 1-carbomethoxy-1-methyl-5-hexenyl radicals (2) with various substituents on C6. The calculations have been done by DFT at the B3LYP/6-311++G** level of theory. They show considerable interaction between C5 and the radical centers even in the ground state of(More)
Under H(2), the radical cyclization of appropriate dienes can be catalyzed by cobaloximes. H• can be abstracted from an intermediate (presumably a cobalt hydride) by trityl radicals (Ar(3)C•) or by TEMPO. The rate-determining step in these reactions is the uptake of H(2), which is second order in cobalt and first order in hydrogen; the third-order rate(More)
Under H2 pressure, Co(II)(dmgBF2)2L2 (L = H2O, THF) generates a low concentration of an H• donor. Transfer of the H• onto an olefin gives a radical that can either (1) transfer an H• back to the metal, generating an isomerized olefin, or (2) add intramolecularly to a double bond, generating a cyclized radical. Transfer of an H• back to the metal from the(More)
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