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Die durch Lewis ‐Säuren katalysierte Cyclisierung von Geranylaceton
Author(s) -
SchulteElte Karl H.,
Ohloff Günther
Publication year - 1975
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.19750580104
Subject(s) - chemistry , stereospecificity , lewis acids and bases , diastereomer , yield (engineering) , stereochemistry , acid catalysis , medicinal chemistry , catalysis , organic chemistry , materials science , metallurgy
Geranylacetone ( 1a , 1b ) in the presence of a Lewis acid, undergoes a novel cyclization reaction to yield the two diastereomers 9‐oxabicyclo[3·3·1]nonene 2 and 3 as main products. The formation of 2 and 3 is not stereospecific, i . e . both isomers 1a and 1b produce the same product mixture ( 2 / 3 ∼ 2:1 ratio). This is in contrast to the known Br ø nsted ‐acid catalyzed cyclization of 1 , leading exclusively to the chromenes 4 and 5 in a stereospecific reaction. The reaction mechanisms and the structural assignments are discussed.