Process to obtain benzoxazines to be used for the synthesis of ofloxazine, levofloxazine and derivatives

摘要

PCT No. PCT/ES93/00080 Sec. 371 Date Aug. 31, 1994 Sec. 102(e) Date Aug. 31, 1994 PCT Filed Oct. 6, 1993 PCT Pub. No. WO94/07873 PCT Pub. Date Apr. 14, 1994.A process to obtain benzoxazines useful for the synthesis of Ofloxazine, Levofloxazine and derivatives. The benzoxacines (I) where Xb is an halogen and R1 is H, alkyl or alkenyl of up to 6 atoms of C or aryl, can be obtained by means of cycling a compound of formula (II) through the reaction with triphenylphosphine and ethyl azodicarboxilate. The compounds of formula (II) can be obtained through the reaction of a compound (III) with an adequate epoxide. Through the use of the adequate chiral epoxide it is possible to obtain the enantiomerically desired intermediate and, therefore and selectively, it is possible to obtain the desired final product with the adequate enantiomeric form without the need to carry out a resolution stage. The Compounds (I) are useful and key intermediates for the synthesis of the antimicrobials Oflixazine and Levofloxazine. <IMAGE> (I) <IMAGE> (II)