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An Alternative Access to (±)‐α‐Irones and (±)‐β‐Irone via Acid‐Mediated Cyclisation
Author(s) -
SchulteElte Karl H.,
Pamingle Hervé,
Uijttewaal Arnold P.,
Snowden Roger L.
Publication year - 1992
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.19920750312
Subject(s) - chemistry , yield (engineering) , medicinal chemistry , organic chemistry , stereochemistry , metallurgy , materials science
Acid‐mediated cyclisation of trienone 8 , readily available from 2,3‐dimethylbutanal ( 1 ; five steps: 47% yield), using fluorosulfonic acid (6.8 mol‐equiv.) in 2‐nitropropane at −70°, afforded a 14:9:1 mixture (70% yield) of (±)‐ cis ‐α‐irone ( 9 ), (±)‐ trans ‐α‐irone ( 10 ), and (±)‐β‐irone ( 11 ). Other acidic conditions examined, using 95% aq. H 2 SO 4 solution, 85% aq. H 3 PO 4 solution, or SnCl 4 , gave inferior results.