| 摘要 |
The invention relates to a process for the preparation of compounds of the formula (I) (see formula I) in which R(2) and R(3) independently of one another are - SR(4) or - COOR(5) and R(1), R(4) and R(5) have the meaning indicated in the description, which comprises cyclizing compounds of the formula II (see formula II) in which R(1), R(2) and R(3) have the meaning defined above, in the presence of alkylphosphonic anhydrides to give compounds of the formula (I), then purifying these in as is known per se by salt formation and, if appropriate, subsequent recrystallization and optionally removing radicals introduced for the protection of other functional groups in a manner known per se; and their use as intermediate for the synthesis of active compounds.
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