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Synthesis of carbon‐13 labeled 5‐(diethylphosphono)‐2‐pentanone ethylene ketal, a reagent for synthesis of multi C‐13 labeled steroids
Author(s) -
Degraw Joseph I.,
Christie Pamela H.,
Cairns Thomas
Publication year - 1982
Publication title -
journal of labelled compounds and radiopharmaceuticals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.432
H-Index - 47
eISSN - 1099-1344
pISSN - 0362-4803
DOI - 10.1002/jlcr.2580190807
Subject(s) - chemistry , ethylene , decarboxylation , ethylene oxide , ketone , acetic acid , bromide , organic chemistry , ethylene glycol , yield (engineering) , reagent , alkylation , medicinal chemistry , catalysis , materials science , copolymer , metallurgy , polymer
Alkylation of ethyl acetoacetate‐ 13 C 4 with ethylene oxide and ethylene oxide‐ 13 C 2 afforded 2‐acetylbutyrolactone‐ 13 C 4 ( 4a ) and the hexalabeled form ( 4b ), respectively. Treatment of the lactone with an excess of 48% hydrobromic acid effected decarboxylation with bromide displacement to yield 5‐bromo‐2‐pentanone labeled with 3 or 5 carbon‐13 atoms ( 5 ). The bromo ketone was converted to the ethylene ketal with ethylene glycol and p ‐toluenesulfonic acid catalysis. Displacement of the bromide by sodio diethyl phosphite gave the required ethylene ketals of 5‐(diethylphosphono)‐2‐pentanone ( 7 ). A convenient process for preparation of ethylene‐ 13 C 2 oxide from acetic‐ 13 C 2 acid is also described.