One molecule acts as both an AND and an XOR Boolean logic gate that share the same two photonic inputs. The molecule comprises a half-adder, adding two binary digits with only light as inputs and outputs, and consists of three covalently linked photochromic moieties, a spiropyran and two quinolinederived dihydroindolizines. The AND function is based on the absorption properties of the molecule, whereas the XOR function is based on an off-on-off response of the fluorescence to the inputs that results from interchromophore excited-state quenching interactions. The half-adder is simple to operate and can be cycled many times.
A chemoselective demethylation method for various methoxypyridine derivatives has been developed. Treatment of 4-methoxypyridine with L -selectride in THF for 2 h at reflux temperature afforded 4-hydroxypyridine in good yield; no reaction to anisole occurred. The utility of our method was demonstrated by the efficient synthesis of the metabolic substances of the antiulcer agent omeprazole. Chemoselective
Determination of the Source of the <i>N</i>-Methyl Impurity in the Synthesis of Pemetrexed Disodium Heptahydrate
作者:Douglas P. Kjell、Dallas W. Hallberg、J. Michael Kalbfleisch、Cynthia K. McCurry、Michael J. Semo、Edward M. Sheldon、Jeremy T. Spitler、Ming Wang
DOI:10.1021/op0498013
日期:2005.11.1
The synthesis of PemetrexedDisodium Heptahydrate has consistently resulted in a very low level (ca. 0.02%) unknown impurity. To ensure long-term control, the identity and source of the impurity were desired. Isolation and characterization identified the impurity as the N-methyl derivative. The source was identified as the methyl groups on the peptide coupling agent, 2,6-Dimethoxy-1,3,5-triazine (CDMT)