Potassium cyanide-14C Research Articles

Synthesis of optically active cyphenothrin-14C. 14C-labelling at the carbonyl carbon.

Optically active cyphenothrins, a-cyano-3-phenoxybenzyl (1R) -cis- and (1R) -trans-chrysan-themates were labelled with 14C at the carbonyl carbon for use in metabolic studies. Ethyl glycinate-1-14C hydrochloride (6), prepared from potassium cyanide-14C (2) in the three steps, was condensed with 2, 5-dimethyl-2, 4-hexadiene via the diazo intermediate to give ethyl cis, trans-chrysanthemate-14C (7) . Hydrolysis of the ester 7 followed by geometrical separation gave cis-and trans-chrysanthemic-14C acid (8a and 8b) . Each geometrical isomer (8a or 8b), was optically resolved to afford (1R) -cis- or (1R) -trans-chrysanthemic-14C acid (8c or 8d) . Esterification of 8c and 8d with a-cyano-3-phenoxybenzyl bromide (9) gave (1R) -cis-and (1R) -trans-eyphenothrin- (carbonyl-14C) (la and 1b) in the yields of 4 and 6% from 2, respectively.

Synthesis of optically active cyphenothrin-14C. 14C-labelling at the cyano and the benzyl carbons.

Optically active cyphenothrins, a-cyano-3-phenoxybenzyl (1R) -cis- and (1R) -trans-chrysan-themates, were labelled with 14C independently at the cyano and the benzyl carbons for use in metabolic studies, α-Cyano-14C-3-phenoxybenzyl alcohol (4) prepared from potassium cyanide-14C (2) was condensed with (1R) -cis- or (1R) -trans-chrysanthemoyl chloride (5a or 5b) to give (1R) -cis- or (1R) -trans-cyphenothrin- (cyano-14C) (la or 1b) in the yield of 82 or 95% from 2, respectively. Similarly, a-cyano-3-phenoxybenzyl-a-14C alcohol (12), which was synthesized from barium carbonate-14C (6) in four steps, was esteri feed with 5a or 5b to afford (1R) -cis- or (1R) -trans-cyphenothrin- (benzyl-14C) (lc or id) . The overall yields of 1c and 1d were 61 and 69% from 6, respectively.

14C-labelling of fenpropathrin, .ALPHA.-cyano-3-phenoxybenzyl 2,2,3,3-tetramethylcyclopropanecarboxylate.

α-Cyano-3-phenoxybenzyl 2, 2, 3, 3-tetramethylcyclopropanecarboxylate (fenpropathrin), a new potent synthetic pyrethroid, was labelled with carbon-14 at the cyclopropyl group for studies on its metabolism in mammals, fishes, plants and soils. Condensation of potassium cyanide-14C (2) with 1, 3-diphenyl-2-thiourea (3) in the presence of basic lead carbonate gave 1-eyano-14C-N, N'-diphenylformamidine (4) . Reduction of 4 followed by hydrolysis with barium hydroxide afforded glycine-2-14C (6) . Esterification of 6 with ethanol in the presence of anhydrous hydrogen chloride gave ethyl glycinate-2-14C hydrochloride (7) . Diazotization of 7 followed by condensation with 2, 3-dimethyl-2-butene yielded ethyl 2, 2, 3, 3-tetramethylcyclopropane-1-14C-earboxylate (8) . Hydrolysis of 8 gave 2, 2, 3, 3-tetramethylcyclopropane-1-14C-carboxylic acid (9), which was esteri feed with a-eyano-3-phenoxybenzyl bromide (10) to afford fenpropathrin- (cyelopropyl-1-14C) (1) in 13% yield from 2.

Synthesis of 2‐pyrrolidinone‐5‐14C

AbstractA convenient synthesis of the pharmacological intermediate 2‐pyrrolidione‐5‐14C, was developed using potassium cyanide 14C as starting material. Potassim cyanide‐14C was converted to 2‐pyrrolidinone‐5‐14C in an overall 56% radiochemical yield.