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Synthesis of Highly Functionalized Pentalenes via IntermolecularPauson–Khand Reaction
Author(s) -
Becheanu Armand,
Baro Angelika,
Laschat Sabine,
Frey Wolfgang
Publication year - 2006
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200500966
Subject(s) - chemistry , ozonolysis , pentalene , pauson–khand reaction , hydroxymethyl , norbornadiene , organic chemistry , vinyl acetate , acetylation , reductive amination , catalysis , molecule , biochemistry , polymer , copolymer , gene
A concise synthetic route to highly substituted pentalenones 4 and 5 , respectively, is reported. The key step is a Pauson–Khand reaction of norbornadiene ( 7 ) with the functionalized acetylenes 8 to give the methanoindenone derivatives 6 . 1,4‐Addition of organocuprates resulted in clean formation of 2,3‐ trans ‐disubstituted methanoindenones 9 . After ozonolysis and reductive workup, the bis(hydroxymethyl)pentalenones 10 were obtained in moderate to good yields. A differentiation of the hydroxy groups became possible by lipase‐mediated acetylation with vinyl acetate, giving highly selectively monoacetates 4 with the acetyl group at C‐6 of the pentalene system. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)