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Novel Conversions of Furandiols and Spiroacetal Enol Ethers into Cyclopentenones: Implications of the Isomerization Mechanism of 2‐Furylcarbinols into Cyclopentenones
Author(s) -
Yin BiaoLin,
Wu YuLin,
Lai JinQiang
Publication year - 2009
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200900129
Subject(s) - chemistry , enol , aldol reaction , aldol condensation , isomerization , electrocyclic reaction , intramolecular force , enol ether , acid catalysis , intramolecular reaction , organic chemistry , reaction mechanism , stereochemistry , catalysis , bicyclic molecule
Two acid‐catalyzed conversions of furandiols 8 and its dehydration spiroacetalized products 9 into oxabicyclic cyclopentenones 10 in good to excellent yields are reported. To disclose the mechanism of these conversions, the fact that H 2 O catalyzes the conversion of 9 into 10 is presented and intermediates 9k and 20i have been structurally verified. In addition, two other related conversions of spiroacetal enol ethers 11 and 14 derived from 8 into cyclopentenones are presented, for which an intramolecular aldol reaction is the key step. On the basis of these results, we propose that these conversions occur through an aldol condensation step instead of electrocyclization of the 4π‐electron system, which was previously reported.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)