Premium
Structure‐Odor Correlation, XIX. Synthesis and Olfactory Properties of Various Racemic Theaspirones, Ketoedulans and Edulans
Author(s) -
Weyerstahl Peter,
Meisel Thomas
Publication year - 1994
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.199419940415
Subject(s) - chemistry , isophorone , odor , ionone , steric effects , beckmann rearrangement , derivative (finance) , dehydration , hydrochloric acid , flavor , pyridine , ring (chemistry) , organic chemistry , medicinal chemistry , food science , catalysis , biochemistry , financial economics , economics
Starting from the cheap isophorone derivative 1 and the alkynols 2–4 , we could prepare the key intermediates 9–11 via addition reaction (→ 5–7 ) and hydrogenation. Ring closure of 9–11 led to the theaspirone ( C ) and/or ketoedulan ( E ) series, depending on the reaction conditions used and the steric situation at C‐2. By treatment of 9 with tosyl chloride/pyridine the theaspirone derivative 13 was formed exclusively, whereas 10a, b were converted into mixtures of 14a, b together with the ketoedulan derivatives 20a, b ; the crowded 11 did not react at all. By treatment of 9–11 with hydrochloric acid/acetone 19–21 were readily obtained. Several hydrogenation and dehydration steps under various conditions led to the theaspirones 16–18 , to the ketoedulans 26a, b and 27 , and to the edulans 39a and 40b . – Olfactory evaluation of the theaspirones 16 (harsh, green), 17a (floral, fruity) and 18 (weak, woody) shows the drastic influence of the steric situation at C‐2. The ketoedulans 26a and 27 smell weak, woody. Evaluation of both odor and flavor of 39a and 40b exhibits mostly woody, camphoraceous and fruity tonalities.