Processes for preparing...

Details Processes for preparing... Processes for preparing...

1999-02-03

2001-03-06

Jordan, Charles T. (Department: 1611)

Organic compounds -- part of the class 532-570 series

Organic compounds

Unsubstituted hydrocarbyl chain between the ring and the -c-...

C560S010000, C560S016000, C560S157000

Statutory Invention Registration

active

H0001950

ABSTRACT:

FIELD OF INVENTION
This invention relates to processes for preparing intermediates, particularly of dicarboxylate oxadiazines of Formula I and hydrazine carboxylates of Formula II, which are useful in the preparation of arthropodicidal oxadiazines.
BACKGROUND OF THE INVENTION
WO95/29171 discloses the preparation of arthropocidal oxadiazines from dicarboxylate oxadiazines of Formula I and hydrazine carboxylates of Formula II.
In WO95/29171, compounds of Formula I are prepared by reacting compounds of Formula II with a di(C
1
-C
3
alkoxy)methane in the presence of a Lewis acid, optionally in an inert solvent. The Lewis acids named are P
2
O
5
, BF
3
, SO
3
(0.9 to 4.0 molar equivalent required) and metal trifluoromethanesulfonates (0.1 to 0.5 molar equivalent required). All of the specifically named solvents for this transformation are halogenated (dichloromethane, 1,2-dichloroethane, chlorobenzene, a,a,a -trifluorotoluene). It is stated that when a metal trifluoromethanesulfonate is employed, it is preferable to continuously remove the byproduct alcohol by distillation. In contrast, the process of the present invention allows for the use of a protic acid such as para-toluene sulfonic acid in catalytic quantities, such as 0.1 molar equivalent in a non-halogenated solvent (e.g. toluene) to provide good product quality in high chemical yield.
The need exists for a more efficient process to prepare oxadiazines of Formula I from hydrazine carboxylates of Formula II.
SUMMARY OF THE INVENTION
The present invention pertains to processes for preparing oxadiazine dicarboxylates of Formula I which are racemic or enantiomerically enriched at chiral center*
wherein R
1
is F, Cl, or C
1
-C
3
fluoroalkoxy, R
2
is C
1
-C
3
alkyl, and R
3
is a protecting group such as CO
2
CH
2
(C
6
H
5
) comprising: reacting a compound of Formula II, which is racemic or enantiomerically enriched at*,
with a di(C
1
-C
3
alkoxy)methane in the presence of a protic acid catalyst in an inert solvent under conditions which allow for the prompt removal of the by-product alcohol by distillation.
This invention further pertains to processes for preparing compounds of Formula I as defined above comprising:
(a) reacting a compound of Formula III, which is racemic or enantiomerically enriched at*,
with the compound of Formula IV in the presence of a protic acid catalyst in an inert solvent
H
2
NNHR
3
  IV
to form a compound of Formula II
II
and (b) reacting the compound of Formula II with a di(C
1
-C
3
alkoxy)methane in the presence of the same protic acid catalyst and inert solvent as used in step (a) under conditions which allow for the prompt removal of the by-product alcohol by distillation.
In the above recitations, the term “C
1
-C
3
fluoroalkoxy” refers to methoxy, ethoxy, n-propoxy and iso-propoxy which may be partially or fully substituted with fluorine atoms. Examples of “fluoroalkoxy” include CF
3
O and CF
3
CH
2
O:


REFERENCES:
patent: 5500438 (1996-03-01), Barnette
patent: WO92/11249 (1992-07-01), None
patent: WO93/19045 (1993-09-01), None
patent: WO95/29171 (1995-11-01), None
patent: 95 29171 (1995-11-01), None
A. Fruchier et al., Ourverture d'epoxydes par le N-hydroxycarbamates de methyle; syntheses de tetrahydrodioxazine-1,4,2 ones-3 et de carbomethoxy-2 tetrahydrodioxazines-1,4,2,Bulletin de la Societe Chimique de France, Partie II, II-173-II-182, 1984.
G. Picciola, Sintesi de Acidi Chinazolinonici e Genzossazinonici e Studio Delle Loro Proprieta Antiinfiammatorie,II Farmaco, Edizione Scientifica, 31, No. 9, 655-665, 1976.

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