934559-80-5Relevant articles and documents
Functionalized N-heterocyclic carbene ligands for dual enantioselective control in the Cu-catalyzed conjugate addition of dialkylzinc compounds to acyclic enones
Dohi, Kenta,Kondo, Junko,Yamada, Haruka,Arakawa, Ryuichi,Sakaguchi, Satoshi
, p. 7143 - 7152 (2013/02/22)
A series of highly tunable, functionalized azolium compounds have been synthesized from chiral α-amino acid derivatives such as β-amino alcohols or α-amino esters. The combination of a Cu salt and a chiral azolium efficiently facilitated the asymmetric co
Enders SAMP-hydrazone as traceless auxiliary in the asymmetric 1,4-addition of cuprates to enones
Sammet, Karsten,Gastl, Christoph,Baro, Angelika,Laschat, Sabine,Fischer, Peter,Fettig, Ina
scheme or table, p. 2281 - 2290 (2010/12/29)
Conjugate additions of Gilman cyanocuprates to (5)-N-amino-2- (methoxymethyl)pyrrolidine (SAMP)-hydrazones 4, 5 derived from cyclic and acyclic α,β-unsaturated ketones were investigated. A protocol utilizing copper(II) sulfate/ammonium chloride was evolved, which allowed cleavage of SAMP (S)-1 under the hydrolysis and work-up conditions, followed by recovery of the auxiliary with ethylenediaminetetraacetic acid (EDTA). The enantioselectivity of cuprate additions was dominated for cyclic SAMP-hydrazones 4 by the cuprate alkyl substituent and the ring size, in the case of acyclic arylidene SAMP-hydrazones 5, however, by the nature of the aryl substituent. Electron-donating substituents gave poor enantiomeric excesses, whereas electron-withdrawing groups provided excellent ee values of 98-99%. The configuration of the new stereocenter was determined to be (R). Moreover, a reaction sequence was developed which integrates a tandem 1,4-addition/ methylation and traceless hydrolytic cleavage of the auxiliary (S)-1 in a one-pot reaction, resulting in enantiomerically pure methyl ketones 11-13, each of them with > 99% ee.
