PubMed · 3657546
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C R Johnson, M P Westrick. 1987. Sulfoxides.. https://doi.org/10.1016/0076-6879(87)43054-1
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The synthesis of 1-O-alkyl-2-(R)-hydroxypropane-3-phosphonocholine is described. An efficient alkylation procedure using (NaH/DMSO) catalysis is also described and applied to the synthetic scheme. The key intermediate 1-O-alkyl-2-(R)-O-benzyl-3-bromopropane was phosphonylated using tris(methylsilyl)phosphite; the resulting phosphonic acid was coupled to choline using trichloroacetonitrile/pyridine or triisopropylbenzenesulfonyl chloride/pyridine followed by catalytic hydrogenation to yield 1-O-alkyl-2(R)-hydroxypropane-3-phosphonocholine.
The problems encountered with the production of single and multi-element inductively coupled plasma (ICP) optical emission spectrometry (OES) standards are reviewed. Purity, stability and characterization of starting materials, water and acids have profound effects on the quality of these standards. The trace level contaminants and the form of the starting materials can result in serious analytical errors. Long-term stability of the ICP-OES standard, dependent in part on the storage container composition, plays an important role in the accuracy of ICP-OES calibration. The relationship between inter-element correction factors and the quality of ICP-OES standards is discussed. Finally, some of the factors that must be considered during the manufacture of multi-element standards for instrument calibration, universal and customer-specific applications are delineated.
Reaction of purine nucleosides, such as 2',3'-isopropylideneinosine (1a) and 2',3'-isopropylideneadenosine (1c), with diisobutylaluminum hydride (DIBAL) in dry tetrahydrofurane resulted in the formation of the corresponding 9-(2',3'-isopropylideneribity)purines (2) in good yields. Oxidation of the ribityl derivatives (2) with NalO4 and subsequent reduction with NaBH4 gave the corresponding 9-(2',3',4'-trihydroxybutyl)-purine derivatives (4) in high yields. Deprotection of compounds 2 and 4 in 80% acetic acid gave the corresponding 9-(2',3',4'-trihydroxybutyl)purines (5) and 9-ribitylpurines (6), respectively.