Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2000-04-03
2001-10-02
Owens, Amelia (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C549S376000
Reexamination Certificate
active
06297390
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process for the production of optically active 5-methyl-2-(1-methylbutyl)5-propyl-1,3-dioxane, to the product obtainable by this process and to its use as a perfume.
2. Statement of Related Art
Judging by demand, many natural perfumes are available in totally inadequate quantities. For example 5000 kg of rose blossoms are required to produce 1 kg of rose oil. The consequences are extremely limited annual world production and a high price. Accordingly, it is clear that there is a constant need in the perfume industry for new perfumes with interesting fragrance notes in order to extend the range of naturally available perfumes, to make the necessary adaptations to changing fashion trends and to be able to meet the steady increasing demand for odor enhancers for products of everyday use, such as cosmetics and cleaners.
Accordingly, it is dear that there is a constant need in the perfume industry for new perfumes with interesting fragrance notes in order to extend the range of naturally available perfumes, to make the necessary adaptations to changing fashion trends and to be able to meet the steadily increasing demand for odor enhancers for products of everyday use, such as cosmetics and cleaners.
In addition, there is generally a constant need for synthetic perfumes which can be favorably produced in a consistent quality and which have desirable olfactory properties, i.e. pleasant, near-natural and qualitatively new odor profiles of adequate intensity, and which are capable of advantageously influencing the fragrance of cosmetic and consumer products. In other words, there is a constant need for compounds which have characteristic new odor profiles coupled with high staying power, intensity of odor and emanative power. 5-Methyl-2-(1-methylbutyl)-5-propyl-1,3dioxane 22 (trade name Troënan®)
is a known synthetic perfume obtainable from 2-methyl pentanal 23 (cf. following scheme). The educt 23 is reacted with 2 equivalents of formaldehyde in a crossed Canizzaro reaction to form 2-methyl-2-propylpropane-1,3-diol 24. The diol 24 may then be acetalized with 2-methylpentanal 23 to form Troënan® 22.
By virtue of its privet blossom note, Troënan® is valued for flowery and aromatic formulations, more particularly lily-of-the-valley compositions. It has the advantage over other lily-of-the-valley components that it is stable to alkalis.
Troënan® 22 contains two cis/trans isomers which in turn consist of two enantiomers:
DESCRIPTION OF THE INVENTION
In exploratory investigations conducted by applicants using the technique of “GC Sniffing”, it was surprisingly found that the trans isomer of Troënan® has the typical privet note while the cis isomer has a weak flowery-bergamotish note.
The problem addressed by the present invention was to provide a 5-methyl-2-(1-methylbutyl)-5-propyl-1,3-dioxane with a more attractive odor than the known commercial product Troënan®.
The problem stated above has been solved by an optically active 5-methyl-2-(1-methylbutyl)-5-propyl-1,3-dioxane which was obtained by multistage chiral pool synthesis from enantiomeric (S)-(−)-lactic acid methyl ester 56.
The synthesis according to the invention starts our from commercially obtainable enantiomeric (S)-(−)-lactic acid methyl ester 56 which, in a first step, is reacted to form an N,N-disubstituted amide. After protection of the OH function, the amide group is converted by a Grignard reaction into an &agr;,&bgr;-unsaturated ketone 56. After removal of the protective group and subsequent acetalization, the hydroxy group is converted into the mesylate 57. After the reductive 1,2-rearrangement with the stereo-chemistry intact, a “dehydro-Troënan” 58 is converted by catalytic hydrogenation into the optically active 5-methyl-2-(1-methylbutyl)-5propyl-1,3-dioxane (−)-22.
The
1
H-NMR spectrum of (−)-22 agrees with that of the cis/trans mixture of Troënan® 22.
Determination of the angle of rotation produced a specific rotation angle [&agr;]
20
D
=−2.43°.
An optically active (−)-22 was obtained as a cisatrans mixture by the chiral pool synthesis. It was found that this (−)-22 was surprisingly superior in its olfactory properties to commercially available Troënan® both from the qualitative point of view (typical odor profile) and from the odor intensity point of view (quantitative aspect).
Accordingly, the present invention relates to a process for the production of optically active 5-methyl-2-(1-methylbutyl)-5-propyl-1,3-dioxane by
converting lactic methyl ester into the corresponding N,N-disubstituted amide (aminolysis with piperidine and/or pyrrolidine),
protecting its free OH function by reaction with ethyl vinyl ether in the presence of p-pyridinium tosylate,
subjecting the N-pentamethylene or N-tetramethylene lactamide thus obtained to a Grignard reaction in known manner to form the corresponding &agr;,&bgr;-unsaturated ketone,
removing the protective group introduced in the second stage in known manner (for example by stirring with acetic acid),
acetalizing the ketone function in known manner (for example by reaction with 2-methyl-2-propylpropane-1,3-diol),
mesylating the free OH function by reaction with methane sulfonic acid chloride in pyridine,
subjecting the intermediate product thus obtained to a reductive 1,2-rearrangement in the presence of diisobutyl aluminum hydride and triethyl aluminum with the stereochemistry intact and
converting the dehydro compound thus obtained into the optically active 5-methyl-2-(1-methylbutyl)-5-propyl-1,3-dioxane by catalytic hydrogenation.
The optically active 5-methyl-2-(1-methylbutyl)-5-propyl-1,3-dioxane obtainable by the process according to the invention has a surprisingly strong emanative power and captivates by its intensive privet and muguet note.
The present invention also relates to optically active 5-methyl-2-(1-methylbutyl)-5-propyl-1,3-dioxane obtainable by the process according to the invention.
The present invention also relates to the use of the optically active 5-methyl-2-(1-methylbutyl)-5-propyl-1,3dioxane obtainable by the process according to the invention as a perfume.
REFERENCES:
patent: 4372880 (1983-02-01), Upadek et al.
patent: 30 16 007 (1981-11-01), None
Altenbach Hans-Josef
Markert Thomas
Merkel Dirk
Cognis Deutschland GmbH
Drach John E.
Owens Amelia
Trzaska Steven J.
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