NEW STRATEGIES FOR ENANTIOSELECTIVE SYNTHESES OF 1-ALKYL-1,2,3,4-TETRAHYDROISOQUINOLINES 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
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The chiral rhenium isoquinoline complex [(5-C5H5)Re(NO)(PPh3)(iso-NC9H7)]+ TfO (1) and (CH3)3-SiCH2Li give the addition product [formula omitted] 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 (38) as 8982:1118 diastereomer mixtures. Reactions of 2 and ROTf (R = H/D, (CH3)3SiCH2, CH3) give alkyl-1,4-dihydroisoquinoline complexes [formula omitted] in 8472% yields as 94:6 diastereomer mixtures. Related complexes are prepared from 35 and HOTf. These react with NaBH4/CH3OH to give alkyl-1,2,3,4-tetrahydroiso-quinoline complexes, which are in turn treated with (CH3CH2)4N+ CN to give (5-C5H5)Re(NO)(PPh3)(CN) (17) and the title compounds. A reaction sequence starting with (+)-(S)-1 and (CH3)3SiCH2Li yields [formula omitted] (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 (5-C5H5)Re(NO)(PPh3)(CH3) (CH3OTf/NaBH4; 8853%) and thence to 1 or (+)-(5)-1 (92-74%, >98% ee). A crystal structure and other data confirm the configurations assigned to the preceding compounds. 1993, American Chemical Society. All rights reserved.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
author list (cited authors)
RICHTERADDO, G. B., KNIGHT, D. A., DEWEY, M. A., ARIF, A. M., & GLADYSZ, J. A.
complete list of authors
RICHTERADDO, GB||KNIGHT, DA||DEWEY, MA||ARIF, AM||GLADYSZ, JA