Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Patent
1999-04-20
2000-02-22
Shippen, Michael L.
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C07C 3506
Patent
active
060282312
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to an improved process for the production of the sandalwood fragrance 2-methyl-4-(2,2,3-trimethylcyclopent-3-en-1-yl)-but-2-en-1-ol by Meerwein-Ponndorf reduction of the corresponding aldehyde precursor in the presence of basic amine compounds.
DISCUSSION OF THE RELATED ART
Judging by demand, the availability of many natural fragrances is totally inadequate. From the perfumistic point of view, sandalwood oil is rated particularly highly and is of great value. It is obtained by steam distillation from the heartwood of the sandalwood tree, a tropical semiparasite which occurs in India and Malaysia. Heartwood appears after about 10 years and only begins to develop relatively quickly in 20-year-old trees. Fully grown trees are uprooted at the age of 30 to 60 because the roots are particularly rich in fragrant heartwood [cf. E. T. Morris, Dragoco Report 1983 (30), 40]. It will therefore be appreciated why fragrance researchers are constantly endeavoring to develop suitable substitutes for natural sandalwood oil.
The focal points in the development of suitable substitutes for natural sandalwood oil were outlined by R. E. Naipawer in a review [in: B. M. Lawrence, B. D. Mookherjee, B. J. Willis (Eds.): "Flavors and Fragrances: A World Perspective", Elsevier Publishers, Amsterdam 1988]. In this review, it is mentioned inter alia that, since the middle of the seventies, campholenyl derivatives have played an important part as synthetic fragrances with a sandalwood perfume. A key role in this access to synthetic sandalwood fragrances has been played by the fact that campholene aldehyde (B), the synthesis building block on which the compounds mentioned are based, can readily be obtained from .alpha.-pinene, a natural substance. ##STR1## 2-Methyl4-(2,2,3-trimethylcyclopent-3-en-1-yl)-but-2-en-1-ol, hereinafter referred to in short as "sandalol" (A), is a sought-after fragrance with a pronounced sandalwood perfume. Sandalol has the following structural formula: ##STR2## Sandalol has been known to the expert for some time. Thus, DE-A-19 22 391 teaches that sandalol is obtained by initially subjecting campholene aldehyde to an aldol condensation with propionaldehyde in the presence of strongly basic catalysts, such as alkali metal alcoholates or alkali metal hydroxides, and reducing the R.sub.s,.sup.MD --unsaturated aldehyde obtained to the corresponding alcohol--the sandalol--in a subsequent step. The reduction may be carried out with complex metal hydrides (for example lithium aluminium hydride) or with aluminium alcoholates by the traditional Meerwein Pondorf method.
JP-A2-55/036423 (cf. Chem. Abstr. 93/094886p) describes a special process for the production of sandalol. In this process, campholene aldehyde (B) is initially reacted with propionaldehyde in the presence of sodium hydroxide as basic catalyst very much in accordance with the teaching of DE-A-19 22 391. The R.sub.s,.sup.MD --unsaturated aldehyde (C) formed in this mixed aldol condensation was isolated in a yield of 73.5%. ##STR3## Finally, in another step, this unsaturated aldehyde (C) was reduced with Al[OCH(CH.sub.3).sub.2 ].sub.3 to form the corresponding sandalol (A) in a yield said to amount to 85%.
It is known from the more recent literature that acidic auxiliary reagents, such as trifluoroacetic acid, are capable of accelerating the traditional Meerwein-Ponndorf reduction of carbonyl compounds with aluminium alcohols, cf. for example Tetrahedron Letters 1995, 36 (20), 3571--3572 and 1995, 36 (28), 5085-5088.
DESCRIPTION OF THE INVENTION
Unfortunately, the process for the production of sandalol (A) known from JP-A2-55/036423 is not entirely satisfactory in terms of yield and economy. Accordingly, there was a need for an improved process for producing the compounds (A).
It has now surprisingly been found that "sandalol" (A) ##STR4## can be obtained in high yields by initially subjecting campholene aldehyde and propionaldehyde to an aldol condensation in the usual way and subsequently subjecting the r
REFERENCES:
patent: 5874649 (1999-02-01), Tanaka
E.T.Morris, Dragoco Report, vol.30 (1983) pp. 40-47 (No translation).
Flavors and Fragrances:A World Perspective, Elsevier Publishers (1988) (Title page only).
Chemical Abstracts, vol.93, No.9 (1980) p. 607.
Tetrahedron Letters, vol.36, No.20 (1995) pp.3571-3572.
Tetrahedron Letters, vol.36, No.28 (1995) pp. 5085-5088.
Chemical Abstracts, vol.94, No.15 (1981) p. 648.
Henkel Kommanditgesellschaft auf Aktien
Jaeschke Wayne C.
Murphy Glenn E.J.
Shippen Michael L.
Szoke Ernest G.
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