1276683-75-0Relevant academic research and scientific papers
Enantioselective synthesis of alkyne-substituted quaternary carbon stereogenic centers through NHC-Cu-catalyzed allylic substitution reactions with (i -Bu)2(Alkynyl)aluminum reagents
Dabrowski, Jennifer A.,Gao, Fang,Hoveyda, Amir H.
, p. 4778 - 4781 (2011/06/19)
A catalytic enantioselective method for the formation of alkyne-substituted all-carbon quaternary stereogenic centers is reported. Additions of alkynylaluminums to alkyl-, aryl-, carboxylic ester-, or silyl-substituted allylic phosphates are promoted by 1.0-5.0 mol % loadings of NHC-Cu complexes derived from air-stable and commercially available CuCl2· 2H2O. The requisite Al-based reagents are prepared through treatment of the corresponding aryl-, heteroaryl-, alkyl-, or alkenyl-substituted terminal alkynes with diisobutylaluminum hydride in the presence of 5.0 mol % Et 3N at ambient temperature. The desired 1,4-enynes are obtained in up to 98% yield and >99:1 enantiomeric ratio. Selected Au-catalyzed cyclizations involving the alkyne unit of the enantiomerically enriched products are presented as a demonstration of the methods utility in chemical synthesis.
