a process for the preparation of novel substituted 1 4 dioxa 8 azaspirodecanes of general formula the novel substituted 1 4 dioxa 8 azaspirodecane of general formula has fungicidal activity application_number US 201013260720 A description present invention provides substituted 1 4 dioxa 8 azaspiro 4 5 decane of general formula 1 wherein r1 is selected from the group consisting of alkyl c1 c6 substituted alkyl c1 c6 substituted aryl un and substituted heteroaryl and r2 is selected from the group consisting of halo group hydroxyl group thio group amino group alkyl c1 c6 substituted alkyl c1 c6 substituted aryl un and substituted heteroaryl the present invention further provides a process for the preparation of compound 1 to 6 of substituted 1 4 dioxa 8 azaspiro 4 5 decane of general formula 1 and the said process comprising the steps of a passing dry hcl gas into n substituted 4 piperidone taken in toluene followed by adding glycerol at a temperature of 25 90 u00b0 c to obtain the compound 2 hydroxymethyl 8 phenethyl 1 4 dioxa 8 azaspiro 4 5 decane 1 b reacting the compound 2 hydroxymethyl 8 phenethyl 1 4 dioxa 8 azaspiro 4 5 decane 1 with a reagent selected from 2 chloro 4 bromophenol morpholine 2 chloro 5 chloromethylthiazole benzyl chloride and thiophenol in the presence of catalyst selected from para toluenesulfonic acid ptsa and tetrabutylammonium bromide tbab in organic solvent under stirring at a temperature in the range of 25 120 u00b0 c for a period of 10.