cas 160191-65-1, (4S 4'S)-(-)-2 2'-(3-PENTYLIDENE)BIS(4-&

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Enantio- and diastereoselective palladium catalysed arylative and vinylative allene carbocyclisation cascades
The enantioselective synthesis of heavily decorated spirolactams has been accomplished via an arylative or vinylative allene carbocyclisation cascade. Mediated by silver phosphate, a range of allene-linked pro-nucleophiles and aryl or vinyl iodides were reacted in the presence of catalytic Pd(OAc)2 and chiral bis(oxazoline) ligands to afford the spirolactam products in good yields and high enantio- and diastereoselectivities. The Royal Society of Chemistry 2013.
Li, Meiling,Hawkins, Alison,Barber, David M.,Bultinck, Patrick,Herrebout, Wouter,Dixon, Darren J.
supporting information
p. 5265 - 5267
(2013/06/27)

Enantioselective Cyclopropanation of Allylic Alcohols. The Effect of Zinc Iodide
The effect of zinc iodide on the catalytic, enantioselective cyclopropanation of aliylic alcohols is examined with bis(iodomethyl)zinc as the reagent and bis-methanesulfonamide 7 as the catalyst. Significant rate enhancement was observed when 1 equiv of zinc iodide was present, but more importantly, the enantiomeric excess of the product cyclopropane increased from 80% to 89% for the substrate cinnamyl alcohol. Reaction studies and spectroscopic investigations show that this remarkable influence is the result of reagent modification via a Schlenk equilibrium that produces the more reactive and selective species (iodomethyl)zinc iodide.
Denmark, Scott E.,O'Connor, Stephen P.
p. 3375 - 3389
(2007/10/03)

Preparation of Chiral Bisoxazolines: Observations on the Effect of substituents
A series of enantiomerically pure 4-substituted bisoxazolines 1a-f, 2c, and 2e was prepared from naturally derived or synthetic amino alcohols and malonyl dichloride derivatives.The formation of the bisoxazolines was accomplished in two stages: (1) preparation of the bis-amides of the malonyl derivatives with the amino alcohols and (2) cyclization of the hydroxy amides 4 by either of two general protocols; (1) heating with thionyl chloride in toluene or (2) formation of the bismesylate and then heating with aqueous or alcoholic base.The latter procedure was found to be more reliable especially for bisoxazolines with bulky substitutents at C(4).The C(4) trityl-substituted hydroxy amide 4f produced the bis(acylaziridine) 10 by cyclization on the nitrogen atom using KOH/MeOH, but afforded the desired bisoxazoline 1f by the action of SOCl2/Et3N.The synthesis of the non-naturally derived amino alcohols using the Evans asymmetric azidation procedure is also described.
Denmark, Scott E.,Nakajima, Norijuki,Nicaise, Olivier J.-C.,Faucher, Anne-Marie,Edwards, James P.
p. 4884 - 4892
(2007/10/02)