摘要:

AbstractA continuous three‐step micro‐synthesis of 1,2‐dibromo‐3‐chloropropane, labelled with tritium in position 1 and 2, is described. A specific activity of 10.8 Ci/mmol is obtained. The yield observed in the uninterrupted overall synthesis is appreciably lower than that in the controlled step‐by‐s

ISSN:0362-4803    

DOI:10.1002/jlcr.2580181202

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe efficient and rapid nucleophilic exchange of fluorine by fluoride‐18F ion in aromatic rings is reported here utilizing rubidium‐18F‐fluoride in DMSO on model compounds. Specific activities in the 3 × 104Ci/mol region are readily achievable. Nucleophilic substitution is shown to be an attractive modality for fluorine‐18 labeling of aromatic c

ISSN:0362-4803    

DOI:10.1002/jlcr.2580181203

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

Abstract1‐(4‐Chlorobenzyl)‐3‐methyl‐3‐(2‐hydroxyethyl)‐thiourea labelled with14C at its urea group was synthesised starting from potassium cyanide‐14C, via potassium thiocyanate‐14C, 4‐chlorobenzyl‐thiocyanate‐14C and 4‐chlorobenzyl‐isothiocyanate‐14C. The conditions of the isomerisation of 4‐chlorobenzyl‐thiocyanate‐14C to 4‐chlorobenzyl‐

ISSN:0362-4803    

DOI:10.1002/jlcr.2580181204

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

AbstractRegiospecific syntheses of tritium labelled precocene I (5a) and precocene II (5b), the antijuvenile hormones, have been accomplished. The syntheses involved condensations between 2‐hydroxyacetophenones (1) with acetone‐T to give cross condensation products2which on cyclodehydration furnished 2,2‐dimethyl‐4‐chromanones‐(2‐gem dimethyl‐T) (3). Reduction of3with lithium aluminium hydride gave chroman‐4‐ols (2‐gem dimethyl‐T) (4). Dehydration of4furnished 2,2‐dimethyl‐ chromenes‐ (2‐gem dimethyl‐T) (5). Starting with appropriate acetophenones and acetone‐T, precocene I (7‐methoxy‐2,2‐dimethylchromene) and precocene II (6, 7‐dimethoxy‐2, 2‐dimethylchromene) labelled with tritium in the 2‐gemdimethylpositions, have been synthesised

ISSN:0362-4803    

DOI:10.1002/jlcr.2580181205

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

AbstractAn efficient synthesis of millimolar quantities of high specific activity D‐threo‐chloramphenicol‐1‐3H is described. The key step is the chromatographic separation of the compound from its 1‐epimer, produced in the Ca(B3H4)2reduction of chloramphenicol ketone (D‐α‐dichloroacetyl‐amino‐β‐hydroxy‐p‐nitropropiophenone), by use of the acetonide derivative. Stereochemical aspects of the N‐bromosuccinimide oxidation of chloramphenicol to chloramphenicol ketone have been investigated, and the previously reported [1] specific rotation of chloramphenicol ketone has been corrected. The synthesis of nitrosochlora

ISSN:0362-4803    

DOI:10.1002/jlcr.2580181206

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

Abstract14C2‐Pentaerythritol (14C‐PE) at approximately 8 mCi/mmole was prepared in 76% yield on a 3‐mmole scale via a base‐catalyzed condensation of acetaldehyde‐14C2with 1.5% aqu

ISSN:0362-4803    

DOI:10.1002/jlcr.2580181207

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

AbstractA simple and convenient synthesis of a radiolabeled antihypertensive pyridazinone was developed. The product was purified chromatographically, and the chemical and radiochemical purities of the sample were determined.

ISSN:0362-4803    

DOI:10.1002/jlcr.2580181208

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

Abstract1‐Ethyl‐6‐fluoro‐1,4‐dihydro‐4‐oxo‐7‐(1‐piperazinyl)‐ 3‐quinolinecarboxylic acid (I, AM‐715), a new potent antibacterial agent, was labelled with carbon‐14 at the C‐1 position of the N‐ethyl group for metabolic studies. The synthesis was achieved according to two reaction routes. The overall radiochemical yields of14C‐AM‐715 based on ethyl iodide‐1‐14C from route A and rou

ISSN:0362-4803    

DOI:10.1002/jlcr.2580181209

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

AbstractEfficient methods for synthesising L‐[methy‐13C]methionine from [13C]iodomethane and L‐methionine, and L‐[3,4‐13C2] methionine from [13C2]ethene, are described; the preparation of [3,3‐2H2]methionine and [2,3,3‐2H3]methionine from methionine by an exchange metho

ISSN:0362-4803    

DOI:10.1002/jlcr.2580181210

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

AbstractA synthesis of 1‐14C‐acetylhydrazine by acetylation of hydrazine using 1‐14C‐ethyl acetate and a catalytic amount of activated alumina is de

ISSN:0362-4803    

DOI:10.1002/jlcr.2580181211

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY