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Conjugated Additions of Selenium Containing Enolates to Enones – Enantioselective Synthesis of δ‐Oxo‐α‐Seleno Esters and Their Facile Transformations
Author(s) -
Tiecco Marcello,
Testaferri Lorenzo,
Marini Francesca,
Sternativo Silvia,
Santi Claudio,
Bagnoli Luana,
Temperini Andrea
Publication year - 2005
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.200400686
Subject(s) - chemistry , selenium , enantioselective synthesis , moiety , lewis acids and bases , reactivity (psychology) , organic chemistry , conjugated system , titanium , addition reaction , combinatorial chemistry , catalysis , medicine , polymer , alternative medicine , pathology
Titanium enolates derived from methyl phenylselenoacetate and other acetates bearing a selenium containing chiral auxiliary have been employed to bring about 1,4‐addition reactions to enones. These reactions generate δ‐oxo‐α‐seleno esters in good yields and with excellent regio‐ and diastereoselectivities. The results obtained clearly indicate that the Lewis acids, employed to activate the starting enones towards addition, greatly influence reactivity as well as the stereochemical outcomes of these reactions. TiCl 4 complexation resulted in particularly efficient promotion of the 1,4‐addition. Simple manipulations of the organoselenium moiety allowed some enantiomerically pure δ‐oxo‐α‐camphorseleno esters to be transformed into the corresponding δ‐oxo‐α‐hydroxy or δ‐oxo‐α‐allyl esters or into trisubstituted tetrahydrofurans. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)