Chemistry Reference
In-Depth Information
heterocyclylphenyl)-s-triazine-2,4,6-oxo] and showing 100% e
cacy against, e.g.,
common lambsquarters in a pre-emergence test, were prepared by reacting an
isothiocyanate 305 with a hydrazine followed by reaction of the resulting interme-
diate 306 with phosgene or a phosgene equivalent in the presence of a base [235].
O
N
O
O
N
O
H
N
COOPr
i
NH
COOPr
i
SCN
N
N
N
N
N
+
N
H
NH
O
S
O
F
Cl
F
Cl
305
306
COCl
2
Base
O
N
O
COOPr
i
N
N
N
N
N
S
O
F
Cl
O
307
A similar cyclocarbonylation reaction of a thiourea to a thiazetidinone was de-
scribed in Section 4.3.2 ''Carbamates''.
The addition reaction of the phosgene equivalent 1,1-dichloromethyl methyl
ether (Chloromyl
2
) to alkenes to afford b-chlorinated aldehydes has been used for
the preparation of pyrethroid intermediates [236, 237].
H
2
O
MeOCHCl
2
COOMe
COOMe
Cl
Cl
COOMe
Cl
CHO
OMe
1. Aldehyde
protection
2. NaOH
OHC
COOH
N-Cyanoamidines, such as N
1
-(6-chloro-3-pyridyl)methyl-N
2
-cyanobenzamidine
308, which are precursors of insecticides, can be prepared by treatment of 3-
(benzamidomethyl)-6-chloropyridine with electrophilic agents (e.g. phosgene in a
solvent) in the presence of tertiary amines (Me
3
N) at 0
C, followed by treatment
with an aq. suspension of Ca(CN)
2
at 5
C for 1 h. The yield in the case of 308 was
44% [238].
