Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing
Reexamination Certificate
1999-02-19
2001-07-31
O'Sullivan, Peter (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Amino nitrogen containing
Reexamination Certificate
active
06268534
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a novel method of the synthesis of N,N-Dioleyl-N,N-Dimethylammonium Chloride (DODAC).
BACKGROUND OF THE INVENTION
The following is a brief description of the synthesis of a lipid compound. This summary is not meant to be complete but is provided only for understanding of the invention that follows. This summary is not an admission that any of the work described below is prior art to the claimed invention.
N,N-Dioleyl-N,N-Dimethylammonium Chloride (DODAC) is an amphipathic compound which has been used for a variety of purposes. Several laboratories have reported the use of DODAC for the transfection of nucleic acid molecules into cells and mammalian organs, either independently or mixed with another compound (Ansell et al., International PCT Publication No. WO 96/10390; Wheeler et al, International PCT Publication No. WO 96/04964; Wasan et al, 1996
, Can. J. Pharm. Sci
. 85, 427-33; Reimer et al., 1995
, Biochemistry
34, 12877-83).
DODAC has also been described as a component of certain liquid detergents (Inoe et al., Japanese Patent Application No. JP 08048995); and Inoe et al., Japanese Patent Application No. JP 94-184925), for use in hair treatment (Kaji et al., Japanese Patent Application No. JP 07330552; Yamamoto et al., Japanese Patent Application No. JP 07330551; and Ikeda et al., Japanese Patent Application No. JP 93-235708) and as a fabric softener (Umezawa et al., Japanese Patent Application No. JP 93-168582; Ide et al., Japanese Patent Application No. JP 05059670; Kobauashi et al., Japanese Patent Application No. JP 04222280; Takeuchi et al., Japanese Patent Application No. JP 04108172; and Inokoshi, Japanese Patent Application No. JP 02300381).
Ansell et al., supra describes two methods for the synthesis of DODAC. The first process involves the synthesis of DODAC through the formation of two intermediates for a total of three steps: 1) formation of N-oleyloleoylamide from oleylamine and oleic acid; 2) reduction of N-oleyloleoylamide to dioleylamine; and 3) methylation of dioleylamine to form DODAC.
The second method described in Ansell et al., is a two step approach which uses flammable dimethylamine gas in the first step. The quaternization reaction of this reaction scheme is conducted in the heterogeneous mixture of chloroform and aqueous NaOH at reflux temperature for 16 hours followed by treatment in concentrated hydrochloric acid and repeated extraction through chloroform.
SUMMARY OF THE INVENTION
Methods for the synthesis of DODAC described in the art involve time consuming multiple-step reactions, and in certain instances utilize caustic or harsh chemicals during synthesis and extraction. In the present invention, Applicant describes a novel, fast, cheap and an efficient method for the synthesis of N,N-Dioleyl-N,N-Dimethylammonium Chloride (DODAC). Additionally, the process described in the present invention utilizes non-flammable liquid reagents that are safer to prepare and easier to scale up. The new process also limits the exposure of the DODAC to harsh chemicals, which may potentially increase the yield of synthesis.
In a preferred embodiment, the invention features a process for the synthesis of N,N-dioleyl-N,N-dimethylammonium chloride (DODAC) comprising the steps of oleylation, where oleyl bromide is contacted with oleylamine under conditions suitable for the formation of N,N-dioleylamine; and methylation of the resulting N,N-dioleylamine under conditions suitable for the formation of DODAC.
Oleylation of the amine group on oleylamine occurs through nucleophilic attack by the amine group to form N,N-dioleylamine as shown below:
By “oleylation” is meant, formation of a covalent bond between a hydrocarbon molecule consisting of 18 carbon atoms with a double bond at delta 9 (oleyl group) with a separate atom or molecule.
By “conditions suitable for oleylation” is meant, reaction conditions including reaction temperature of preferably between 80° C. and 150° C., specifically between 90° C. and 150° C., more specifically between 100° C. and 150° C.; a reaction time of preferably between 30 and 90 minutes specifically between 45 and 75 minutes, more specifically between 50 and 60 minutes. Those skilled in the art will recognize that the reaction temperature and time may be varied without significantly affecting the reaction.
By “nucleophilic attack” is meant, a reaction where the nucleophile (the group that forms a new bond with carbon) attaches to a carbon atom displacing the leaving group.
In another preferred embodiment, oleylation is carried out in the presence of oleyl methone sulfonate or oleyl p-toluene sulfonate or the like, in place of oleyl bromide.
In yet another preferred embodiment, N,N-dioleylamine is reacted with methanol, KHCO
3
, and trimethyl iodide (CH
3
I) under conditions suitable for the methylation of the amine group on N,N-dioleylamine to form the quaternary ammonium compound, N,N-dioeyl-N,N-diemethylammonium chloride.
By “conditions suitable for methylation” is meant, that the reaction occurs at a temperature preferably between 20° C. and 50° C., specifically between 23° C. and 37° C., more specifically 25° C. and 30° C. and reaction times of preferably between about 24-72 hours, specifically 36-50 hours, more specifically 40-48 hours. Those skilled in the art will recognize that the reaction temperature and time may be varied without significantly affecting the reaction. By “about” is meant that the precise time of reaction may be altered without affecting the result of the reaction. For a time period it is generally ±10% or ±2-5%.
Other features and advantages of the invention will be apparent from the following description of the preferred embodiments thereof, and from the claims.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The drawings will be first described briefly.
REFERENCES:
patent: 5785992 (1998-07-01), Ansell et al.
patent: 2300381 (1990-12-01), None
patent: 4108172 (1992-04-01), None
patent: 4222280 (1992-08-01), None
patent: 7-3650 (1995-01-01), None
patent: 7-69837 (1995-03-01), None
patent: 7330552 (1995-12-01), None
patent: 7330551 (1995-12-01), None
patent: 8048995 (1996-02-01), None
patent: 8-48994 (1996-02-01), None
patent: 96/04964 (1996-02-01), None
patent: 96/10390 (1996-04-01), None
Wasan et al., “Plasmid DNA is protected against ultrasonic cavitation-induced damage when complexed to cationic liposomes,”Can J. Pharm. Sci85:427-433 (1996).
Reimer et al., “Formation of novel hydrophobic complexes between cationic lipids and plasmid DNA,”Biochemistry34:12877-12883 (1995).
Lyon & Lyon LLP
O'Sullivan Peter
Ribozyme Pharmaceuticals Inc.
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