Patent CA-1049538-A (CA)
Inventor: SANDERS JAMES M
IPC: C07D311/78
Filed: 1975-02-24
Granted: 1979-02-27
Abstract: Abstract:  Process for producing isochromans having the structure:          wherein R1 and R2 are each (i) separately selected from the group consisting of hydrogen, lower alkoxyl, lover alkyl, and (ii) taken together, selected from the group consisting of benzo, cyclopentano, cyclo-hexano, naphtho, monoalkyl cyclopentano, polyalkyl cyclopentano, monoalkyl cyclohexano and polyalkyl cyclohexano, and R3 and R4 are the same or different and are selected from the group consisting of hydrogen and lower alkyl comprising the steps Or intimately admixing:     (A)  An alkanol having the structure:       (B)  An acetal having the structure:       (wherein R5 and R6 are the same or different alkyl; and (C)  A protonic acid selected from the group consisting of p-toluene sulfonic acid and phosphoric acid, and heating the resulting mixture for a period of time whereby a substantial amount of the isochroman having the above structure is formed.      The production of isochromans has been shown in the art and certain novel isochromans have recently been disclosed with an outstanding musk fragrance. Such isochromans especially adapted for perfumery by virtue of their fragrance properties have been disclosed in Heeringa & Beets U.S. Patent 3,360,530 issued on December 26, 1967.      A number of routes are available for the pro-duction of isochromans, such as those set forth in U.S. Patent 3,360,530 and one of the most straight-forward of these routes is treatment of a Friedel-Crafts reactant with an alkylene oxide under Friedel-Crafts conditions to form an aryl alkanol.  The aryl alkanol is then isolated and thereafter reacted with formaldehyde to cyclialkylate the alcohol.  The efficiency of this multi-stage process leaves much to be desired because of yield impairment due to the large amount of working required.      U.S. Patent 3,532,719 set forth a process for producing such isochromans which solved a number of the problems of the processes set forth in 3,360,530.     U.S. Patent 3,532,719 provided a more simplified more economical process for producing isochromans which comprises reacting a Friedel-Crafts reactant with an alkylene oxide in the presence of aluminum chloride to form an aryl alkanol, partially deactivating the aluminum chloride after formation of the aryl alkanol, and cyclialkylating the aryl alkanol with formaldehyde in the presence of the partially deactivated aluminum chloride to form the isochroman.  The disadvantage of such procedures for the preparation of isochromans is in the second step wherein chloromethyl methyl ethors may be involved which have been reported to be health hazards and accordingly special precautions are required when handling.  The preparation and use of such chloromethyl methyl ethers and the use of aluminum chloride complexes give rise to the release of hydrogen chloride vapors and formation of aqueous hydrogen chloride solutions requires the use of more expensive glass lined vessels due to the more corrosive mixtures in the reaction.     Steyn and Holzapfel, Tetrahedron, 23 4449 (1967), reports the reaction of a halo aryl alkanol with chloromethyl methyl ether and zinc chloride to give an isochroman according to the following reaction:       Meyer and Turner, Tetrahedron, 27 2609 (1971), reports the reaction of a methoxy aryl alkanol with sodium hydride and chloromethyl methyl ether to give a methoxy aryl alkanol methyl ether.  Subsequent treatment of the methoxy aryl alkanol methyl ether with toluenesulfonic acid is indicated to yield isochromans according to the following reaction: