Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2001-11-02
2004-03-16
McKane, Joseph K. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C549S021000
Reexamination Certificate
active
06706891
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to processes for the preparation of 4,5-bisimino-[1,3]dithiolanes and 2,3-bisimino-[1,4]dithianes. Certain of these processes have two-step sequences involving (i) conversion of an oxalamide to a dithiooxalamide, followed by (ii) conversion of the dithiooxalamide to either a 4,5-bisimino-[1,3]dithiolane or a 2,3-bisimino-[1,4]dithiane. 4,5-bisimino-[1,3]dithiolanes and 2,3-bisimino-[1,4]dithianes are useful as ligands for olefin polymerization catalysts (U.S. Pat. No. 6,103,658; PCT Intl. Appl. WO 0050470A2).
BACKGROUND OF THE INVENTION
Nickel and palladium complexes of bidentate N,N-donor ligands have recently been shown to be useful as olefin polymerization catalysts (Ittel et al.,
Chem. Reviews
2000, 100, 1169). There is a need therefore for efficient methods of synthesizing such ligands. In addition to the methods described in the literature reviewed by Ittel et al. (
Chem. Reviews
2000, 100, 1169), Gonioukh et al. (WO 01/21586 A1) have recently described methods for this purpose. Notwithstanding these developments, there remains a need for further improvements in efficiency and scope to provide general and cost effective routes to such ligands.
SUMMARY OF THE INVENTION
In a first aspect, this invention provides a straightforward, efficient and cost effective process for the preparation of a 4,5-bisimino-[1,3]dithiolane or a 2,3-bisimino-[1,4]dithiane of general formula I, useful as ligands for olefin polymerization catalysts;
wherein an oxalamide of general formula II
is reacted with a reagent capable of transforming an amide to a thioamide, which is then reacted with a reagent of general formula III;
wherein,
R and R
1
are each, independently hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl or heteroatom connected substituted hydrocarbyl;
Q is hydrocarbyl or substituted hydrocarbyl; and
X and Y
1
are each, independently, a leaving group.
In a second aspect, this invention relates to a straightforward, efficient and cost effective process for the preparation of compounds of the general formula IV, useful as ligands for olefin polymerization catalysts, in a single reactor, without isolation of any intermediates;
wherein a diketone of general formula V is reacted with a protected hydrazine in the presence of an acid to form a protected amino pyrrole, the resultant protected amino pyrrole is then reacted with an &agr;-diketone of general formula VI in the presence of an acid;
wherein:
R
5a
and R
5b
are each, independently, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl or heteroatom connected substituted hydrocarbyl;
R
6a
is H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl or heteroatom connected substituted hydrocarbyl; and
R
7a
and R
7b
are each hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl.
DETAILED DESCRIPTION OF THE INVENTION
In a first aspect, this invention relates to a process for the preparation of a 4,5-bisimino-[1,3]dithiolane or a 2,3-bisimino-[1,4]dithiane of general formula I by reacting a substituted oxalamide of general formula II with a reagent capable of transforming an amide to a thioamide to form a dithiooxalamide compound. The second step of the process involves reaction of the dithiooxalamide compound with a compound of general formula III to provide the 4,5-bisimino-[1,3]dithiolane or 2,3-bisimino-[1,4]dithiane of general formula I. This process, along with preferred embodiments, is described in more detail in the discussion and examples below.
The oxalamide may be any oxalamide of general formula II, which may be prepared by any number of methods known to those skilled in the art, including, but not limited to, reaction of oxalic dihydrazide with a 1,4-diketone and reaction of a primary amine with oxalyl chloride. Preferred R and R
1
groups in general formula II are chosen from the group consisting of
wherein:
R
2a-2c
are each, independently, H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl or heteroatom connected substituted hydrocarbyl; R
3a-3b
are each, independently hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl or heteroatom connected substituted hydrocarbyl; and R
4a
is H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl or heteroatom connected substituted hydrocarbyl. Preferably R
2a
and R
2c
are each, independently, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl or heteroatom connected substituted hydrocarbyl. More preferably, R
2a
and R
2c
are each, independently, hydrocarbyl or substituted hydrocarbyl. Examples of suitable R
2a
and R
2c
groups include, but are not limited to, methyl, ethyl, isopropyl, isobutyl, tert-butyl, phenyl, 4-tert-butyl phenyl, 4-methyl phenyl, 4-methoxy phenyl, 4-trifluoromethyl phenyl, 4-nitro phenyl and 3,5-diphenyl phenyl.
Preferably, R
3a
and R
3b
are each, independently, hydrocarbyl or substituted hydrocarbyl. Examples of suitable R
3a
and R
3b
groups include, but are not limited to, methyl, ethyl, isopropyl, isobutyl, tert-butyl, phenyl, 4-tert-butyl phenyl, 4-methyl phenyl, 4-methoxy phenyl, 4-nitro phenyl and 3,5-diphenyl phenyl.
Preferably, R
4a
is H, hydrocarbyl or substituted hydrocarbyl. Examples of suitable R
4a
groups include, but are not limited to, H, methyl, ethyl, isopropyl, tert-butyl, isobutyl, phenyl, —COOR
5
, —COR, —CONR
5
2
, —CONHR
5
, cyano and nitro; wherein R
5
is hydrocarbyl or substituted hydrocarbyl. Examples of suitable R
5
groups include, but are not limited to, methyl, ethyl, isopropyl, tert-butyl, isobutyl and phenyl.
Examples of a reagent capable of transforming an amide to a thioamide include, but are not limited to, P
4
S
10
and 2,4-bis(4-methoxyphenyl)-1,3-dithia-2,4-diphosphetane-2,4-disulfide.
The first step of the process may be run in an inert solvent, preferably toluene or xylene. When phosphorous pentasulfide is used as the source of sulfur, the reaction may be conducted at temperatures ranging from about 25 to about 200° C., preferably at temperatures ranging from about 75 to about 150° C. With other sources of sulfur, the preferred temperature range will generally be similar but will best be determined by routine experimentation. Pressures at or above about 1 atm are preferred.
Step two of the process to prepare a 4,5-bisimino-[1,3]dithiolane or a 2,3-bisimino-[1,4]dithiane of general formula I involves reaction of the dithiooxalamide formed in step (i) of the process with a compound of general formula III; wherein Q is hydrocarbyl or substituted hydrocarbyl; and X and Y
1
are each, independently, leaving groups. Preferably, Q is —CH
2
CH
2
—, —CH
2
—, —CO— or —CS—; more preferably, Q is —CH
2
CH
2
—. When X and Y
1
are both bromo and Q is —CH
2
CH
2
—, the reaction may be conducted at temperatures ranging from about 0 to about 100° C., preferably at temperatures ranging from about 25 to about 50° C. With other X, Y
1
, and Q, the preferred temperature range will generally be similar but will best be determined by routine experimentation. Pressures at or above about 1 atm are preferred.
A “leaving group” is any species that can be expelled by a nucleophile in an S
N
2 reaction or is easily dissociated in an S
N
1 reaction. Examples of suitable leaving groups include, but are not limited to, chloride, bromide, p-toluene sulfonate, methane sulfonate and trifluoromethane sulfonate. Preferably, X and Y
1
are each, independently, bromide.
Step (ii) of the process may further comprise a base to aid in the removal of the acidic dithiooxalamide proton. Preferably, the base is an alkali metal hydroxide or ammonium hydroxide. Preferred alkali metal hydroxides are sodium hydroxide and potassium hydroxide.
Step (ii) of the process may be run in neat compound III, as a solution in an inert organic solvent, in a biphasic mixture
Mackenzie Peter Borden
Moody Leslie Shane
Ponasik, Jr. James Allen
Eastman Chemical Company
Graves, Jr. Bernard J.
McKane Joseph K.
Small Andrea D.
Wood Jonathan D.
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