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Prins Cyclization in Ionic Liquid Hydrogen Fluoride Salts: Facile and Highly Efficient Synthesis of 4‐Fluorinated Tetrahydropyrans, Thiacyclohexanes, and Piperidines
Author(s) -
Kishi Yuichiro,
Inagi Shinsuke,
Fuchigami Toshio
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.200800872
Subject(s) - prins reaction , chemistry , stereoselectivity , ionic liquid , hydrogen fluoride , fluorine , catalysis , salt (chemistry) , fluoride , hydrogen , organic chemistry , medicinal chemistry , inorganic chemistry
Prins cyclization of homoallylic alcohols with various aldehydes was investigated in ionic liquid hydrogen fluoride (HF) salts, which played roles as a reaction medium, a catalyst, and a fluorine source. The reaction afforded the corresponding 4‐fluorinated tetrahydropyrans in excellent yields with a high stereoselectivity ( cis form exclusively). When benzaldehydes having a strongly electron‐donating group at the para position were used, the stereoselectivity was lost in this system. In order to apply this method to the synthesis of other 4‐fluorinated heterocyclic compounds, we also carried out thia‐Prins and aza‐Prins cyclization in HF salt and successfully obtained 4‐fluorinated thiacyclohexanes and piperidines, respectively.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)