SYNTHESIS OF C(2)HALOMETHYL SUBSTITUTED DERIVATIVES OF 2,3-DIHYDRO-1,3-BENZOXAZ-4-ONES

In the pursuit of biologically active compounds we required as a key i ntermediate 2,3-dihydro-1,3-benzoxaz-4-ones having a halomethylene moi ety at C(2), i.e. 3 (R2= H or alkyl, R3=CH2X). The standard procedure for the preparation of this class of compounds is the condensation of salicylamide derivatives 1 with the proper aldehydes1-5 and ketones5,6 . Usually, hydrochloric acid or sulphuric acid is used as catalyst and the water formed is cocommittently removed using a dehydrating agent or by azeotropic destillation7. These procedures did not serve our pur pose as the required alpha-substituted aldehyde or ketone as such is u nstable under the conditions employed. Here we report that employment of acetals and ketals 2 affords the desired compound 3; yields are app reciable when the proper reaction conditions are used.