Process for the preparation of 1-Propyl-2, 4, 5- trimethoxybenzene from toxic beta-asarone of Acorus calamus or from crude calamus oil containing beta-asarone

Abstract

The invention relates to a process for the preparation of 1-Propyl-2, 4, 5-trimethoxybenzene useful as a aroma molecule and as a starting material and intermediate for preparation of various drugs. The process comprises providing crude calamus oil or β-asarone in a solvent, hydrogenating the solution in the presence of a catalyst, filtering the catalyst and removing the solvent under reduced pressure, subjecting the reduced calamus oil to column of silica gel chromatography using an eluent to obtain the desired product in liquid form with 85-97% purity.

We claim:  
     
         1 . A process for the preparation of 1-Propyl-2, 4, 5-trimethoxybenzene of the formula I useful as a aroma molecule and as a starting material and intermediate for preparation of various drugs,  
       
         
           
           
               
               
           
         
       
       the said process comprising the steps of 
 (a) providing crude calamus oil or β-asarone in a solvent selected from the group consisting of ethanol, methanol, THF, DCM, toluene, and chloroform;  
 (b) hydrogenation of the solution in the presence of a catalyst selected from the group consisting of Pd/C, Pt, Pd(OH) 2 , Raney nickel and ammonium formate at a pressure in the range of 10-40 psi hydrogen gas and at a temperature in the range of 15-40° C.;  
 (c) filtering the catalyst and removing the solvent under reduced pressure in the range of 10-100 mm Hg;  
 (d) subjecting the reduced calamus oil to column of silica gel chromatography using an eluent to obtain the desired product in liquid form with 85-97% purity.  
 
     
     
         2 . A process as claimed in  claim 1  wherein the catalyst comprises 5-10% Pd/C.  
     
     
         3 . A process as claimed in  claim 1  wherein the calamus oil used is of tetraploid or hexaploid origin.  
     
     
         4 . A process as claimed in  claim 1  wherein the toxicity of the hydrogenated calamus oil is two times less than that of the starting calamus oil.  
     
     
         5 . A process as claimed in  claim 1  wherein the reduced calamus oil has a novel honey and roses aroma.  
     
     
         6 . A process as claimed in  claim 1  wherein the 1-Propyl-2,4,5-trimethoxybenzene obtained has a novel sweet, ylang, slightly spicy and fruity aroma.  
     
     
         7 . A process as claimed in  claim 1  wherein the calamus oil is extracted from asarone rich plants such as  Asarum europaeum, Crowea angustifolia  and  Heterotropa yakusimensis.    
     
     
         8 . Use of reduced calamus oil in toiletry soap, shaving cream and tobacco products.  
     
     
         9 . Use of 1-Propyl-2,4,5-trimethoxybenzene as a multipurpose additive in mouthwash, tooth paste, antiseptic soap products, chewing gum flavour and in spicy products.  
     
     
         10 . Use of 1-Propyl-2,4,5-trimethoxybenzene as an inexpensive and simple starting material for the preparation of 3-propyl-5,6-dimethoxysalicylamide based antipsychotic drug 5, 6-dimethoxy-N [(1-ethyl-2-pyrrolidinyl) methyl]-3-propylsalicylamide.  
     
     
         11 . Use of 1-Propyl-2,4,5-trimethoxybenzene to obtain products for use as flavour, in perfumery industries and as starting material for various important drugs and for new organic compounds by bromination, oxidation, reduction, coupling reaction, allylic hydroxylation, dimerisation, formylation, Grignard reaction, oxymercuration-demercuration, demethylation, alkylation and epoxidation.  
     
     
         12 . A process for the preparation of 5, 6-dimethoxy-N [(1-ethyl-2-pyrrolidinyl) methyl]-3-propylsalicylamide from 1-Propyl-2, 4, 5-trimethoxybenzene of the formula I.