- Thionyl chloride-pyridine mediated rearrangement. Synthesis of potential intermediates for (+) and (±)-occidol.
-
Thionyl chloride-pyridine mediated rearrangement of cylohexadienyl alcohols (2) and (8) has provided hyposantonin (3) and tetrahydronaphthalene (9), respectively, which in turn have served as potential intermediates for the synthesis of optically active a
- Banerjee,Vera
-
-
Read Online
- A short-step synthesis of sesquiterpene lactone, 1-oxoeudesma-2,4-dien-11βh-12, 6α-olide, isolated from artemisia herba-alba and its derivatives
-
1-Oxoeudesma-2,4-dien-11βH-12,6α-olide(1) isolated from the genus Artemisia herb-alba was synthesized from α-santonin in a two-step sequence. The key step is the 1,3 oxidative rearrangement of dienol 7.
- Kawamata,Nagashima,Nakai,Tsuji
-
p. 139 - 148
(2007/10/03)
-
- Relative Stabilities of the Desmotroposantonins
-
Equilibration of (-)-α-desmotroposantonin methyl ether (6), (+)-β-desmotroposantonin methyl ether (7), and isohyposantonin (8) with K2CO3 in xylene gives the same 56:44 mixture of isomers at C-11.Although acid-catalyzed isomerization of (-)-α-desmotroposantonin (2) affords (+)-β-desmotroposantonin (3) in good yield, the deoxy analogue of 2, isohyposantonin (8), gives an approximately 1 to 1 mixture of 8 and β-desmotroposantonin analogue (11) with acid 10 as the major product.These results indicate that the published data which indicate that the β-isomers are significantly more stable than their α-epimers are based on reactions in which equilibrium was not reached.NMR studies at 200 MHz show that the conformation of the lactone ring in the α- and β-isomers is not the same.A conformation is suggested for α-desmotroposantonin on the basis of the NMR data, and an explanation is offered for the stability relationships in the desmotroposantonin series.
- Huffman, John
-
p. 2901 - 2904
(2007/10/02)
-