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US 7,842,840 B2Granted
Process for the preparation of trans-2,3-disubstituted naphthoquinones
AssigneeLaboratorio Chimico Internazionale S.p.A.
InventorsAntonio Nardi, Mara Sada, Annibale Salvi, Stefano Maiorana
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Abstract
The invention concerns a new process for the preparation of naphthoquinones, in particular an improved process for the preparation of 2,3-disubstituted 1,4-naphthoquinones, in the trans configuration.
Claims22
A process for the preparation of a compound of formula (I)
- wherein R′ is hydrogen and R″ is selected from hydrogen C1-6-alkyl, C1-6-alkoxy, aryl-C1-6-alkoxy, C1-6-alkyl-C1-6-alkoxy, halogen, perhalo-C1-6-alkyl, phenyl optionally substituted with one or two groups chosen from atoms of halogen and C1-6-alkyl,
- which comprises reacting a compound of formula (II), in cis form or as a cis/trans mixture,
- wherein
- R′ and R″ are as defined above, and
- R′″ is an atom of hydrogen or a Pr protecting group hydrolysable in an acid environment, with concentrated sulfuric acid, at a temperature below +20° C.
2 more elements
Dependencies are inferred from the claim text.