Method for producing alkenylnitrobenzene derivatives unbranched in the 1′-position

1. An alkenylnitrobenzene of the formula (I)

where

R 1 is halogen, or —CR′(CF 3 ) 2 and R′ is selected from the group consisting of H, F and O—C 1-4 -alkyl; and

R 2 is t-butyl or cyclopropyl.

2. An alkylnitrobenzene of the formula (VI)

where

R 1 is halogen, or —CR′(CF 3 ) 2 and R′ is selected from the group consisting of H, F and O—C 1-4 -alkyl.

3. A process for preparing the alkenylnitrobenzene of the formula (I) according to claim 1 , the process

comprising

(i) reacting a 2-nitrotoluene of the formula (II)

wherein R 1 is defined as in claim 1 ,

with an aldehyde of the formula (III)

R 2 —CHO  (III)

wherein R 2 is defined as in claim 1 ,

in the presence of a base to give a hydroxyalkylnitrobenzene of the formula (IV)

in which

R 1 and R 2 are as defined above;

(ii) converting the hydroxyalkylnitrobenzene of the formula (IV) obtained from (i) to a compound of the formula (V)

in which R 1 and R 2 are as defined above, and X is a halogen atom or a leaving group;

and

(iii) eliminating HX from the compound of the formula (V) to give an alkenylnitrobenzene of the formula (I),

or

(iv) eliminating H 2 O from the hydroxyalkylnitrobenzene of the formula (IV) to give an alkenylnitrobenzene of the formula (I).

4. The process as claimed in claim 3 , wherein the eliminating HX in (iii) is conducted under base catalysis or thermally.

5. The process as claimed in claim 3 , wherein the eliminating H 2 O in (iv) is conducted under acid catalysis or thermally.

6. The process according to claim 3 , wherein the process comprises

(i) reacting a 2-nitrotoluene of formula (II)

wherein R 1 is defined as in claim 3 ,

with an aldehyde of formula (III)

R 2 —CHO  (III)

wherein R 2 is defined as in claim 3 ,

in the presence of a base to give a hydroxyalkylnitrobenzene of formula (IV)

wherein R 1 and R 2 are defined as in claim 3 ;

(ii) converting the hydroxyalkylnitrobenzene of formula (IV) obtained in (i) to a compound of formula (V)

wherein

R 1 and R 2 are defined as in claim 3 , and

X is a halogen atom or a leaving group;

and

(iii) eliminating HX from the compound of formula (V) to give the alkenylnitrobenzene of formula (I).

7. The process of claim 6 , wherein the eliminating HX in (iii) is conducted under base catalysis or thermally.

8. The process according to claim 3 comprising

(a) reacting a 2-nitrotoluene of formula (II)

wherein R 1 is defined as in claim 5 ,

with an aldehyde of the formula (III)

R 2 —CHO  (III)

wherein R 2 is defined as in claim 5 ,

in the presence of a base to give a hydroxyalkylnitrobenzene of formula (IV)

wherein R 1 and R 2 are defined as in claim 3 ;

and

(b) eliminating H 2 O from the hydroxyalkylnitrobenzene of formula (IV) to give the alkenylnitrobenzene of formula (I).

9. The process of claim 8 , wherein the eliminating H 2 O in (b) is conducted under acid catalysis or thermally.