84519-64-2Relevant academic research and scientific papers
Enantioselective preparation of C2-symmetrical ferrocenyl ligands for asymmetric catalysis
Schwink, Lothar,Knochel, Paul
, p. 950 - 968 (2007/10/03)
Corey - Bakshi - Shibata (CBS) reduction of the 1,1'-diacylmetallocenes 5 and 7 provides the C2-symmetrical diols 4 and 10, which proved to be useful starting materials for stereo-controlled ligand synthesis. Diols 4 and 10 can be easily converted to a wide range of diamines, diphosphines, and dithioacetates by nucleophilic substitution of the hydroxyl function with full retention of configuration. Furthermore, the aminophosphines 30 and 31 become easily accessible. Compounds 30 and 31 have been used as ligands in enantioselective cross-coupling of racemic secondary Grignard reagents with vinyl bromides. A selectivity up to 93% ee could be reached for the first time in the preparation of (S)-(E)-1,3-diphenyl-1-butene (34b), which was transformed into the enantiomerically pure chiral building block 37 with a pseudoasymmetric center in a straightforward, three-step synthesis.
ASYMMETRIC COUPLING OF ARYLMAGNESIUM BROMIDES WITH ALLYLIC ESTERS
Hiyama, Tamejiro,Wakasa, Noriko
, p. 3259 - 3262 (2007/10/02)
Arylmagnesium bromides were allowed to react with 3-penten-2-yl (or 2-buten-1-yl) acetate (pivaloate, carbonate, or methyl ether) in the presence of NiCl2 catalyst to afford (R)-4-aryl-2-pentene (or 3-aryl-1-butene) in high chemical and optical yields.
Alkylation of Allylic Derivates. 4. On the Mechanism of Alkylation of Allylic N-Phenylcarbamates with Lithium Dialkylcuprates
Goering, Harlan L.,Kantner, Steven S.,Tseng, Chung Chyi
, p. 715 - 721 (2007/10/02)
Alkylation of allylic N-phenylcarbamates by deprotonation, complexation with CuI in THF, and addition of 1 equiv of RLi results in syn γ-alkylation in both cyclic and acyclic systems.This procedure gives higher stereo- and regiospecificity than when allylic N-phenylcarbamates are reacted with 3 equiv of etheral LiCuR2.A mechanism is presented which incorporates an intramolecular oxidative addition leading to a ?-allyl complex (3) which undergoes reductive elimination to give the syn γ-alkylation product.
