Catalysis of Cope-type rearrangements of bis-homoallylic hydroxylamines is demonstrated using chiral thiourea derivatives. This formal intramolecular hydroamination reaction provides access to highly enantioenriched alpha-substituted pyrrolidine products and represents a complementary approach to metal-catalyzed methods.
Catalysis of Cope-type rearrangements of bis-homoallylic hydroxylamines is demonstrated using chiral thiourea derivatives. This formal intramolecular hydroamination reaction provides access to highly enantioenriched alpha-substituted pyrrolidine products and represents a complementary approach to metal-catalyzed methods.
Highly Enantioselective Addition of Me<sub>2</sub>Zn to Aldehydes Catalyzed by ClCr(Salen)
作者:Pier Giorgio Cozzi、Peter Kotrusz
DOI:10.1021/ja057969d
日期:2006.4.1
enantiomeric excesses are obtained in the addition of Me2Zn catalyzed by commercially available ClCr(Salen). Broad scope, simple procedure, room temperature, low catalyst loading are the characteristics of this new enantioselective process, which uses the rather unreactive Me2Zn. Enantiomeric excesses in the range of 71-99% are obtained with all the aldehydes tested.
Under catalysis of Pd(OAc)2-(P-n-Bu)3, Et2Zn promotes a variety of allyl alcohols to undergo nucleophilic allylation of aliphatic aldehydes and ketones at room temperature and provides homoallyl alcohols in 60–90 and ca. 60% isolated yield, respectively. The reaction is irreversible and kinetically controlled, and unique regio- and stereoselectivities observed for the allylation with unsymmetrically
Gold(I) complexes are the most active catalysts for alkoxy- or hydroxycyclization and for skeletalrearrangement reactions of 1,6-enynes. Intramolecular alkoxycyclizations also proceed efficiently in the presence of gold(I) catalysts. The first examples of the skeletalrearrangement of enynes by the endocyclic cyclization pathway are also documented. Iron(III) is also able to catalyze exo and endo
Pd-Catalyzed Nucleophilic Alkylation of Aliphatic Aldehydes with Allyl Alcohols: Allyl, 2-Tetrahydrofuryl, and 2-Tetrahydropyranyl Ethers as Useful C3, C4, and C5 Sources