Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Patent
1991-07-15
1993-05-25
Ivy, C. Warren
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
564305, 568313, C07D21350, C07C 4572, C07C 49217
Patent
active
052141519
DESCRIPTION:
BRIEF SUMMARY
FIELD OF INVENTION
This invention relates to a method for the preparation of .alpha.,.beta.-unsaturated ketones represented by general formula (II) ##STR2## where R is a heterocyclic group with nitrogen atom in the ring or a phenyl group with electron donative substituents (hereinafter referred to as Compound II), Compound (II) is extremely important as an intermediate for pharmaceuticals and agricultural chemicals.
DESCRIPTION OF RELATED ART
Conventionally known methods for the preparation of Compound II include a synthetic method by aldol condensation of aldehyde and acetone [described in such documents as Ber. 35 3569 (1902)] and a method that aldehyde and acetoacetate are Knovenagel condensed, hydrolyzed and decarboxylated [described in such documents as J. Org. Chem. 22 1451 (1957)]. The methods are not applicable to industrial manufacturing since the yield is generally low.
An object of this invention is to provide methods for the preparation of .alpha., .beta.-unsaturated ketones which are excellent as industrial manufacturing methods.
SUMMARY OF THE INVENTION
The inventors carried out various studies to accomplish the above purposes, and found that Compound (II) can be obtained with good yield by reacting specific aldehydes with acetone, in a water solvent, using specific catalysts, while heating, and thus have accomplished this invention.
That is, this invention is a method for the preparation of .alpha.,.beta.-unsaturated ketones represented by general formula (II) ##STR3## where R is a heterocyclic group with nitrogen atom in the ring or a phenyl group with electron donative substituents which comprises reacting aldehydes represented by general formula (I) of one or two or more compounds selected from the group consisting of perhydroisoindole and pyrrolidine which may have substituents, in a water solvent, at 20.degree. C. to 40.degree. C., and then reacting at the reflux temperature.
Aldehydes represented by general formula (I) used in this invention include benzaldehydes with electron donative substituents such as p-(N,N-dimethylamino) benzaldehyde and 2,4,6-trimethylbenzaldehyde; and heterocyclic aldehydes with nitrogen atom in the ring such as 2-pyridine carbaldehyde, 3-pyridine carbaldehyde and 4-pyridine carbaldehyde.
Compounds used as catalyst include perhydroisoindole and pyrrolidine represented by the following formula which may be substituted; ##STR4## where R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are hydrogen or lower aliphatic groups.
Their concrete examples are pyrrolidine and pyrrolidines substituted at the 3 and/or 4 positions such as 3-methylpyrrolidine, 3-ethylpyrrolidine, 3,3-dimethylpyrrolidine, 3,3-diethylpyrrolidine, 3,4-dimethylpyrrolidine and 3,4-diethylpyrrolidine.
Two or more of these catalysts can be used by mixing. Water is indispensable as a catalyst. A reaction in an organic solvent results in extremely low yield. ##STR5##
The reaction proceeds according to the above reaction equations (1) and (2). If R is a heterocyclic group containing N in the ring such as pyridyl group, Reaction (2) proceeds more, and .alpha.,.beta.-unsaturated ketones are formed from .beta.-hydroxyketones during the addition reaction or post treatment. Therefore, it is difficult to isolate .beta.-hydroxyketones. .alpha.,.beta.-unsaturated ketones may be formed by addition reaction at room temperature followed by dehydration with strong acid. However it is rather preferable to convert from .beta.-hydroxyketones to .alpha.,.beta.-unsaturated ketones by heating during the addition reaction.
If R is a phenyl group with electron donative substituents such as N-dimethylamino group or trimethyl group, the equilibrium of (1) shifts to the aldehyde side, and the reaction does not proceed. Therefore Reaction (2) is advanced by heating and the equilibrium is shifted to synthesize .alpha.,.beta.-unsaturated ketones.
A way of implementing the preparation method for Compound I is described in detail in the following;
1.5 to 20 times moles, preferably 3 to 10 times moles, to a mole of Compound I, of aceto
REFERENCES:
patent: 4945184 (1990-07-01), Pugach et al.
Chem. Abstract: U.S.S.R. from: Otkrytiya, Izobret. 1985(32), 242 Kaku Tsutomu et al. Nippon Soda Co., Ltd.
Derwent Abstract: U.S.S.R. from: Otkrytiya, Izobret, 1985(32), 242 Kaku Tsutomu, et al. Nippon Soda Co., Ltd.
Kyotani Tadashi
Nakajima Masashi
Tsukashima Keiichi
Ivy C. Warren
M. Mach D. Margaret
Mason, Jr. Joseph C.
Nippon Soda Co. Ltd.
Smith Ronald E.
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