D. Van Haver

The synthesis of 4-desoxy-2-azapodophyllotoxins

Abstract 4-Desoxy-2-azapodophyllotoxins, tetrahydroisoquinoline analogues of podophyllotoxin, have been synthesized and evaluated for their anti-tumor activities.

Cyclopentanones—VIII : Stereochemistry of the lithium-liquid ammonia reduction of 2,3-dialkyl-4-hydroxy-2-cyclopentenones

Abstract 2,3-Dialkyl-1,4-cyclopentanediols are obtained by lithium-liquidammonia-alcohol reduction of 2,3-dialkyl-4-hydroxy-2-cyclopentenones. The configuration of the diastereoisomers formed was proved by 1H-NMR spectroscopy and by chemical evidence. In the most abundant isomer the alkyl groups are trans and each is in trans position to the vicinal hydroxyl function. In another diastereoisomer formed in substantial amount the alkyl groups have a cis orientation and are trans to the vicinal hydroxyl function. The 1H-NMR parameters found are more useful generally for configurational assignments to synthetic and modified prostaglandins.

Preparative-scale high-performance liquid chromatography on analytical columns

Abstract The capacity of analytical high-performance liquid chromatographs for preparative-scale separations in the adsorption as well as in the reversed phase mode is shown to be about ten times greater than generally believed. A preparative column of 50 x 0.68 cm which can be handled by an analytical instrument can separate 0.1-1 g of relatively complex mixtures. The displacement and elution chromatographic modes are compared.

Configurational assignment and 1H-NMR spectral parameters of the isomeric 1,4-diacetoxy-2,3-dimethylcyclopentanes

Abstract All six 1,4-diacetoxy-2,3-dimethyl-cyclopentanes have been prepared starting from 2, 3-dimethyl-4-hydroxy-2-cyclopentenone. 1 H-NMR spectral parameters, allowing configurational assignment, are discussed.

Routine production of H11CN and [11C]-1-Aminocyclopentanecarboxylic acid

Abstract The production of H 11 CN using the 14 N(p, α) 11 C reaction, was studied. The yield is 140 mCi/μA at saturation (EOB). From 1.8 Ci of H 11 CN 140 mCi of [ 11 C]ACPC are produced routinely and under remote-control. Chemical and pharmaceutical controls showed that the product is suitable for injection.

Synthesis of [1-11C]iodoethane for the preparation of [11C]ethyl labelled radiopharmaceuticals

Abstract A method for the synthesis of [ 11 C]iodoethane, a useful precursor for labelling of molecules of biomedical interest, has been developed. 11 CO 2 prepared by irradiation of nitrogen gas with 18 MeV protons, is converted into [ 11 C]ethanol by a Grignard reaction with methylmagnesium bromide, followed by reduction with lithium aluminum hydride and hydrolysis with hydrochloric acid. [ 11 C]Iodoethane is produced by reaction of [ 11 C]ethanol with hydriodic acid. The purification is performed by gaschromatography on Porapak Q. For a 20 min irradiation at, 15 μA intensity the method yields about 370 mCi† of radiochemically pure [ 11 C]iodoethane with a specific activity of 180–300 mCi/μmol at the end of synthesis, 23 min after irradiation.

On the use of volume maps in the conformational analysis of vitamin D analogs

Dot maps used to represent the calculated conformations of the side chain of vitamin D derivatives are improved by replacing dots by coloured balls to create volume maps and to identify particular energy windows. Two procedures to define a relative activity volume, based on a pair of analogs with distinctly different biological activity and conformational behaviour, are presented.

Fully automatic, microprocessor-controlled system for the production of 111CO2, 111CH3I and 111C-labeled radiopharmaceuticals

An automated system for the production of 11C-labeled radiopharmaceuticals, using 11C-CH3I as a precursor, has been developed. The whole procedure, including irradiation, production of 11C-CH3I, synthesis of the labeled molecule and isolation of the final product is controlled by a microprocessor. Between 30 and 80 mCi of 5 different radiopharmaceuticals are produced routinely with this system.

Remote-controlled production of [11C]antipyrine

Abstract A rapid method for preparation and purification of [11C]antipyrine using [11C]methyl iodide as radio-active precursor is described. Methylation of 5-benzyloxy-3-methyl-l-phenylpyrazole (radiochemical yield 45–50%), followed by reversed-phase liquid chromatography, affords 60–70 mCi of the labeled radiopharmaceutical. The preparation takes 50 min from the end of the irradiation and is carried out using a shielded synthesis system with remote control of all operations.

Synthesis of CD-ring modified 1α,25-dihydroxy vitamin D analogues: Five-membered D-ring analogues

Abstract Vitamin D analogues characterized by the absence of a C-ring (D-ring analogues) are described.