Title of Invention	PROCESS FOR THE PREPARATION OF SUBSTITUED PYRANES
Abstract	Substituted pyranes such as 2-ethinyl-tetrahydro-2,6,6-trimethylpyran are prepared 5 from dehydrolinalool or higher homologues thereof by heating or treatment with microwaves in the presence of a solid acid.

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The present invention is concerned with a novel process for the preparation of substituted pyranes of the general formula I in the presence of a solid acid to elevated temperature or irradiation with microwaves. The process of the present invention proceeds in high yields and in short reaction time. Further, the process of the present invention has the advantage that the use of a solvent and unwanted pressure increase in closed reaction vessels is avoided. Gm 18.6.01 The term "microwave" as used herein refers to the region of the electromagnetic spectrum having fre-quencies of 30 GHz to 300 MHz thus corresponding to wavelengths of 1 cm to 1 m. In order not to interfere with wave-lengths for Radar (1 cm - 25 cm), household or in-dustrial microwave heaters are required to operate at either 12.2 cm (2.45 GHz) or 33.3 cm (918 MHz). Thus, in a preferred embodiment of the invention, the term microwaves refers particularly to such wavelenghts. In the process of this invention, conventional microwave equipment can be used. Microwave equipment suitable in the process of this invention is supplied, e.g., by the firms MLS, Leutkirch, Germany (Lavis Multiquant 1000); or MILESTONE Inc., Monroe,CT 06468, USA (Ethos reactors). Conveniendy, the irradiation in the process of this invention is carried out applying a power of irradiation of from about 600 to 1200 W, more preferably from about 800 to about 1000 W. The solid acid used as a catalyst in the present invention is suitably a strong organic acid, such as a polymeric sulfonic acid, e.g., a polyperfluoroalkylene sulfonic acid, particularly Deloxan® ASP (Degussa, Frankfurt/M., Germany) or Nafion® NR 50 (DuPont, Wilmington, Del.,USA), or an anionic ion exchange resin such as Amberlyst® 15 (Rohm & Haas, Philadelphia, Pa.,USA); or an inorganic acid, such as sulfuric acid/silizium dioxide, or silicates such as zeolithes, e.g., Zeocat®, and Wessalith® types (Degussa), montmorillonites, e.g. Montmorillonit K 10 and KSF (Fluka, Buchs, Switzerland) and mesoporous (pore size 2-50 nm) metal-doped silica gels (Degussa) Particularly preferred are microporous (pore size In a preferred aspect, \l\ R^ and R^ are each methyl. However, any compound of the general formula I wherein R", R" and R^ are, independently, lower alkyl, can be prepared by the process of this invention. The term lower alkyl as used herein denotes straight or branched chain alkyl groups having up to 7 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, sekbutyl, tert.butyl, n-pentyl and isomers thereof. if the process of the presence invention is carried out by exposing the compound of formula il to elevated temperature, the compound of formula II is heated, in the presence of a solid acid, to a temperature of about 40°C to about 100°C, preferably to about 60""C to about lOCC. However, in a preferred aspect, the present invention is concerned with the preparation of a compound of formula I wherein a compound of the general formula 1 is excposed to microwave irradiation. The process according to the present invention is carried out in dry state, i.e., in the absence of solvents. Prior to exposure to elevated temperature or irradiation, the starting compound of formula II is suitably thoroughly mixed with the catalyst, e.g., by suspending the catalyst in a solution of the compound of formula 11, e.g., in dichloromethane or an ether such as methyl-tert.butyl ether, with stirring and subsequent removal of the solvent or, if the catalyst is a porous material, simply adding the compound of formula II to the catalyst. The catalyst is suitably used in an amount of about.0.5 to about 10, preferably about 1 to about 2 parts of weight per part of weight of compound of formula 11. The following Examples illustrate the invention further. The reactions were carried under Ar atmosphere. The microwave equipment used was Lavis Multiquant 1000 (MLS). HTTP means 2-ethynyl-tetrahydro-2,6,6-trimethylpyran; DLL means D,L-3,7-dimethyl-6-octen-l-in-3-ol (dehydroUnalool). Example 1 A solution of 13.82 g (0.09 mol) of dehydroUnalool (II, R", R^ and R^ = methyl) in 200 ml of methyl tert.butyl ether was added to 28.35 g of Zeocat® Z6-05-02 and stirred for 30 min. The reaction mixture was evaporated (40°C, 300 mbar) and the resulting solid was subjected to microwave irradiation (600 W power for 4 s). The product was separated from the solid by dissolving in 300 ml acetone and evaporating the solvent in vacuo. The crude 2-ethinyl-tetrahydro-2,6,6-trimethylpyran was obtained in 13.30 g (96.2 %) yield as yellowish liquid. Example 2 Example 4 D,L-3,7-dimethyl-6-octen-l-in-3-ol (DDL) (0.92 g, 6 mmol) was adsorbed on the solid acid (2 g). After evaporation of the solvent (experiments usmg mesoporeous silica gel were carried out with a solution of DDL in methyl tert.buty! ether (MTBE); experiments using Wessalith® Day P were carried out without solvent), the solid was stirred for 60 min at room temperature, 40 °C, 60 °C, 80 °C, and 100 °C. After cooling to room temperature, the organic material was desorbed with 250 ml MTBE, and the organic layer was concentrated in vacuum (40 "C, 50 mbar). The crude product was analyzed by GC, The results are summarized below; Example 5 500 ml (456.6 g, 2.87 mol) of DLL and 16 g of Amberlyst 15 were heated to 70° C. After 7 h reaction time the conversion was 92 % (control by gaschromatography). The rnixture was destillated at 99.4 "0147 mbar. There were thus obtained 370 g of HTTP (purity 97.32 %), corresponding to a yield of 82.4 %. WE CLAIM: 1. Process for the preparation of compounds of the general formula I 2. The process as claimed in claim 1, wherein a compound of formula II is irradiated with microwaves in the presence of a solid acid. 3. The process as claimed in claim J or 2, wherein the solid acid is a zeolithe. 4. The process as claimed in claim 3, wherein the zeolithe is a micToporous zeolithe with a pore size 5. The process as claimed in any one of claims 1 to 4, wherein the amount of solid acid used is 0.5 to 10, preferably 1 to 2 parts of weight per part of weight of compound of formula 11. 6. The process as claimed in any one of claims 1 to 5 wherein a microwave source of 800 to 1000 W is used. 7. The process as claimed in any one of claims 1 to 6, wherein in the compound of formula II R1, R2 and R3 are methyl.

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725-mas-2001 abstract duplicate.pdf

725-mas-2001 abstract.pdf

725-mas-2001 claims duplicate.pdf

725-mas-2001 claims.pdf

725-mas-2001 correspondence others.pdf

725-mas-2001 correspondence po.pdf

725-mas-2001 description (complete) duplicate.pdf

725-mas-2001 description (complete).pdf

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