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14 C‐Labelling of prallethrin SF, (4 S )‐1‐OXO‐2‐propargyl‐3‐methylcyclopent‐2‐en‐4‐yl (1 R )‐CIS‐ and (1 R )‐ trans ‐chrysanthemates
Author(s) -
Kanamaru Hiroshi,
Kawahara Kazuo,
Kamada Takeshi,
Yoshitake Akira,
Nakatsuka Iwao
Publication year - 1986
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.2580230912
Subject(s) - chemistry , magnesium bromide , propargyl , medicinal chemistry , bromide , isomerization , propargyl bromide , methyl iodide , lithium aluminium hydride , magnesium , organic chemistry , catalysis
Both of the components of prallethrin SF [ (4S) ‐1‐oxo‐2‐propargyl‐3‐methylcyclopent‐2‐en‐4‐yl (1R)‐cis,trans ‐chrysanthemate], a novel potent insecticidal pyrethroid, were labelled with carbon‐14 at the cyclopentenyl‐2 position for use in metabolic studies. Carbonation of 2‐lithio‐5‐methylfuran ( 4 ) with carbon‐14 dioxide ( 3 ) gave 5‐methyl‐2‐[carboxyl‐ 14 C]furoic acid ( 5 ). Reduction of 5 with lithium aluminium hydride followed by oxidation with manganese dioxide afforded 5‐methyl[carbonyl‐ 14 C]‐furfural ( 7 ). Modified Grignard reaction of 7 with propargyl bromide and magnesium in the presence of mercuric chloride yielded 1‐(5‐methyl‐2‐furyl)[1‐ 14 C]but‐3‐yn‐1‐ol ( 8 ). Molecular rearrangement of 8 followed by isomerization afforded 2‐propargyl‐3‐methyl[2‐ 14 C]cyclopent‐2‐en‐4‐ol‐1‐one ( 9 ) in 30% yield from barium [ 14 C]carbonate ( 2 ). Direct optical‐resolution of 9 by preparative HPLC with a chiral‐phase column gave (+)‐ (4S) and (‐)‐ (4R) isomers ( 10 and 11 ) quantitatively. Condensation of 10 with (1R)‐cis ‐ or (1R)‐trans ‐chrysanthemoyl chloride ( 12a or 12b ) yielded (4S),(1R)‐cis‐ or (4S),(1R)‐trans ‐[cyclopentenyl‐2‐ 14 C]prallethrin ( 1a or 1b ). Both overall radiochemical yields of 1a and 1b were about 9% from 2 .