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Generation of Secondary, Tertiary, and Quaternary Centers by Geminal Disubstitution of Carbonyl Oxygens
Author(s) -
Seebach Dieter
Publication year - 2011
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201003823
Subject(s) - geminal , chemistry , nucleophile , medicinal chemistry , aryl , alkyl , carbonyl group , stereochemistry , organic chemistry , catalysis
Methods for replacing the carbonyl oxygen by two new substituents (CO→CR 1 R 2 ) are discussed in this Minireview, whereby R may be H, NR 2 , alkyl, allyl, benzyl, vinyl, alkynyl, aryl, heteroaryl, or acyl groups. The most frequently used starting materials for geminal disubstitution with the formation of two CC bonds (R 1 ,R 2 ≠H, NR 2 ) are amides and thioamides, which react with organometallic nucleophiles RM (M=Li, MgX, CeX 2 , TiX 3 , ZrX 3 ) to give tertiary sec‐ and tert‐alkylamines. Quaternary centers can be built directly from ketones by treatment with Me 3 Al, MeTiCl 3 , or Me 2 TiCl 2 (R 1 R 2 CO→R 1 R 2 CMe 2 ). The scope and limitations of the various methods and mechanistic models are briefly discussed. The remarkable variety and diversity of structures thus accessible are demonstrated by numerous examples.