57680-87-2Relevant articles and documents
Enhancing effects of salt formation on catalytic activity and enantioselectivity for asymmetric hydrogenation of isoquinolinium salts by dinuclear halide-bridged iridium complexes bearing chiral diphosphine ligands
Kita, Yusuke,Yamaji, Kenta,Higashida, Kosuke,Sathaiah, Kandula,Iimuro, Atuhiro,Mashima, Kazushi
, p. 1915 - 1927 (2015/01/30)
Asymmetric hydrogenation of 1- and 3-substituted and 1,3-disubstituted isoquinolinium chlorides using triply halide-bridged dinuclear iridium complexes [{Ir(H)(diphosphine)} 2(μ -Cl)3]Cl has been achieved by the strategy of HCl salt formation of isoquinolines to afford the corresponding chiral 1,2,3,4-tetrahydroisoquinolines (THIQs) in high yields and with excellent enantioselectivities after simple basic workup. The effects of salt formation have been investigated by time-course experiments, which revealed that the generation of isoquinolinium chlorides clearly prevented formation of the catalytically inactive dinuclear trihydride complex, which was readily generated in the catalytic reduction of salt-free isoquinoline substrates. Based on mechanistic investigations, including by 1H and 31P{1H} NMR studies and the isolation and characterization of several intermediates, the function of the chloride anion of the isoquinolinium chlorides has been elucidated, allowing us to propose a new outer-sphere mechanism involving coordination of the chloride anion of the substrates to an iridium dihydride species along with a hydrogen bond between the chloride ligand and the N-H proton of the substrate salt.
Expanded substrate scope and catalyst optimization for the catalytic kinetic resolution of N-heterocycles
Hsieh, Sheng-Ying,Binanzer, Michael,Kreituss, Imants,Bode, Jeffrey W.
supporting information, p. 8892 - 8894 (2012/11/07)
The scope, reactivity, and selectivity of the chiral hydroxamic acid-catalyzed kinetic resolution of chiral amines are improved by a new catalyst structure and a more environmentally friendly reaction protocol. In addition to increasing selectivity across all substrates, these conditions make possible the resolution of N-heterocycles containing lactams or other basic functional groups that can inhibit the catalyst.
New strategies for enantioselective syntheses of 1-alkyl- and 1,4-dialkyl-1,2,3,4-tetrahydroisoquinolines: Diastereoselective additions of nucleophiles and electrophiles to isoquinoline mediated by an easily resolved and recycled chiral transition metal auxiliary
Richter-Addo, George B.,Knight, D. Andrew,Dewey, Michael A.,Arif, Atta M.,Gladysz
, p. 11863 - 11873 (2007/10/02)
The chiral rhenium isoquinoline complex [(η5-C5H5)Re(NO)(PPh 3)(iso-NC9H7)]+ TfO- (1) and (CH3)3-SiCH2Li give the addition product (η5-C5H5)Re(NO)(PPh3)(N?CH = CHC(CH)4CCHCH2Si(CH3)3) (2) in 71% yield as a 94:6 SS,RR/SR,RS diastereomer mixture. Similar reactions with RMgX (R = (CH3)2CH, CH3CH2, C6H5CH2, CH3(CH2)2, CH3, CH3(CH2)3) give analogous adducts (3-8) as 89-82:11-18 diastereomer mixtures. Reactions of 2 and ROTf (R = H/D, (CH3)3SiCH2, CH3) give alkyl-1,4-dihydroisoquinoline complexes [(η5-C5H5)Re(NO)-(PPh3)(N = CHCHRC(CH)4CCHCH2Si(CH3)3)] + TfO- in 84-72% yields as 94:6 diastereomer mixtures. Related complexes are prepared from 3-5 and HOTf. These react with NaBH4/CH3OH to give alkyl-1,2,3,4-tetrahydroisoquinoline complexes, which are in turn treated with (CH3CH2)4N+ CN- to give (η5-C5H5)Re(NO)(PPh3)(CN) (17) and the title compounds. A reaction sequence starting with (+)-(S)-1 and (CH3)3SiCH2Li yields (+)-(SS)-NHCH2-CH(CH2Si(CH3) 3)C(CH)4CCHCH2Si(CH3)3 (84% overall, 88% ee) and (+)-(S)-17 (82%, >98% ee). Other optically active alkyl tetrahydroisoquinolines are similarly prepared. Complexes 17 and (+)-(S)-17 are converted to (η5-C5H5)Re(NO)(PPh3)(CH 3) (CH3OTf/NaBH4; 88-53%) and thence to 1 or (+)-(S)-1 (92-74%, >98% ee). A crystal structure and other data confirm the configurations assigned to the preceding compounds.
