Substituted dihydro 3-halo-1H-pyrazole-T-carboxylates, their preparation and use
View Patent ↗This invention relates to a compound of Formula I, a method for its preparation and its use in the preparation of a compound of Formula II wherein R 1 , R 2 , R 3 , X and n are as defined in the disclosure. This invention also discloses preparation of compounds of Formula III wherein R 1 , R 2 , R 6 , R 7 , R 8 and n are as defined in the disclosure. Also disclosed are certain intermediates of Formula 4 for the preparation of compounds of Formula I wherein X is N and R 2 , R 3 and n are as defined in the disclosure.
1. A compound of Formula II
wherein
R 1 is halogen;
each R 2 is independently C 1 –C 4 alkyl, C 2 –C 4 alkenyl, C 2 –C 4 alkynyl, C 3 –C 6 cycloalkyl, C 1 –C 4 haloalkyl, C 2 –C 4 haloalkenyl, C 2 –C 4 haloalkynyl, C 3 –C 6 halocycloalkyl, halogen, CN, NO 2 , C 1 –C 4 alkoxy, C 1 –C 4 haloalkoxy, C 1 –C 4 alkylthio, C 1 –C 4 alkylsulfinyl, C 1 –C 4 alkylsulfonyl, C 1 –C 4 alkylamino, C 2 –C 8 dialkylamino, C 3 –C 6 cycloalkylamino, C 3 –C 6 (alkyl)cycloalkylamino, C 2 –C 4 alkylcarbonyl, C 2 –C 6 alkoxycarbonyl, C 2 –C 6 alkylaminocarbonyl, C 3 –C 8 dialkylaminocarbonyl or C 3 –C 6 trialkylsilyl;
R 3 is H or C 1 –C 4 alkyl;
X is N or CR 4 ;
R 4 is H or R 2 ; and
n is 0 to 3, provided when X is CH then n is at least 1.
2. A compound of claim 1 wherein n is 1 to 3.
3. A compound of claim 1 wherein
R 1 is Cl or Br;
each R 2 is independently Cl or Br, and one R 2 is at the 3-position; and
X is N.
4. A method of preparing a compound of Formula II of claim 1 comprising treating a compound of Formula I
with an oxidant, optionally in the presence of an acid, to form a compound of Formula II; and when a compound of Formula I wherein R 3 is C 1 –C 4 alkyl is treated, optionally converting the compound of Formula II wherein R 3 is C 1 –C 4 alkyl formed by said treating with an oxidant to a compound of Formula II wherein R 3 is H.
5. The method of claim 4 wherein n is 1 to 3.
6. The method of claim 4 wherein the oxidant is hydrogen peroxide or a persulfate salt.
7. The method of claim 6 wherein X is CR 4 ; and the oxidant is hydrogen peroxide.
8. The method of claim 6 wherein X is N; the oxidant is potassium persulfate; and said treating with an oxidant is carried out in the presence of sulfuric acid.
9. The method of claim 4 wherein in Formula I wherein R 1 is Cl or Br; each R 2 is independently Cl or Br, and one R 2 is at the 3-position; R 3 is C 1 –C 4 alkyl; and X is N.
10. A method of preparing a compound of Formula II of claim 1 comprising (1) treating a compound of Formula 4
wherein R 3 is C 1 –C 4 alkyl;
with a halogenating agent to form a compound of Formula I
wherein R 3 is C 1 –C 4 alkyl;
(2) optionally converting the compound formed in (1) to a compound of Formula I wherein R 3 is H;
(3) treating said compound of Formula I wherein R 3 is C 1 –C 4 alkyl or H with an oxidant, optionally in the presence of an acid, to form a compound of Formula II; and when a compound of Formula I wherein R 3 is C 1 –C 4 alkyl is treated,
(4) optionally converting the compound of Formula II wherein R 3 is C 1 –C 4 alkyl formed by said treating with an oxidant to a compound of Formula II wherein R 3 is H.
11. A compound of claim 1 wherein R 1 is Cl or Br; n is 1; R 2 is Cl or Br, and is at the 3-position; R 3 is selected from hydrogen, methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl and tert-butyl; and X is N.
12. A compound of claim 1 wherein R 1 is Cl; n is 1; R 2 is Cl, and is at the 3-position; R 3 is hydrogen; and X is N.
13. A compound of claim 1 wherein R 1 is Cl; n is 1; R 2 is Br, and is at the 3-position; R 3 is hydrogen; and X is N.
14. The compound of claim 1 wherein R 1 is Br; n is 1; R 2 is Cl, and is at the 3-position; R 3 is hydrogen; and X is N.
15. The compound of claim 1 wherein R 1 is Br; n is 1; R 2 is Br, and is at the 3-position; R 3 is hydrogen; and X is N.