| 摘要 |
Processes for the preparation of a compound of the formula (B) having the following steps: provision of a compound of the formula (A), intramolecular reaction of the compound of the formula (A) in the presence of an aluminium siloxide of the formula (I) wherein in formula (I) the radicals Ra', Ra'', Ra''', Rb', Rb'', Rb''', Rc', Rc'', Rc''' independently of one another denote hydrogen or an organic radical, are described.
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