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Neue Wege zu Pentalen‐Vorstufen
Author(s) -
You Shaochun,
Chai Shengyong,
Schwarz Nadine,
Neuenschwander Markus
Publication year - 1997
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19970800520
Subject(s) - pentalene , chemistry , dilithium , dimer , stereochemistry , molecule , organic chemistry , ion , deprotonation
New Pathways to Precursors of Pentalene Pentalene dimers 2 and 3 are easily available in moderate yields by CuCl 2 ‐induced oxidative coupling of dilithium‐pentalenediide ( 5 ) ( Scheme 1 ). On the other hand, NBS bromination of 1,5‐dihydropentalene ( 4 ) or of 1,2‐dihydropentalene ( 8 ) gives unstable 1‐bromo‐1,2‐dihydropentalene ( 9 ), while subsequent in ‐ situ elimination with Et 3 N exclusively gives syn ‐ cis ‐pentalene dimer 2 in moderate yields ( Scheme 3 ). NMR‐Spectroscopic evidence for compounds 2 , 3 , and 9 is presented, and mechanistic alternatives for the formation of pentalene dimers 2 and 3 are discussed.