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Diastereoselective Protonation, Substitution and Addition Reactions at Pseudotetrahedral Rhenium Complexes
Author(s) -
Bock Frank,
Fischer Frank,
Radacki Krzysztof,
Schenk Wolfdieter A.
Publication year - 2010
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200901011
Subject(s) - chemistry , rhenium , diastereomer , protonation , ligand (biochemistry) , medicinal chemistry , chelation , nucleophile , enantiomer , stereochemistry , substitution reaction , palladium , catalysis , inorganic chemistry , organic chemistry , ion , biochemistry , receptor
The chiral N,P ligand P(Me)(Ph)[8‐(2‐methylquinolinyl)] ( 3 ) was synthesized and separated into its enantiomers via diastereomeric palladium complexes. The reactions of 3 and ( R P )‐ 3 with [CpRe(CO)(NO)(NCMe)]BF 4 ( 7 ) gave thediastereomeric complexes [CpRe(CO)(NO){P(Me)(Ph)(C 10 H 8 N)}]BF 4 [ 8 and ( R Re , S P / S Re , S P )‐ 8 ], which, upon borohydride reduction, yielded the corresponding methyl complexes [CpRe(NO){P(Me)(Ph)(C 10 H 8 N)}(CH 3 )] [ 9 and ( R Re , S P / S Re , S P )‐ 9 ]. Treatment of 9 with HBF 4 under carefully controlled conditions gave the diastereomerically pure chelates [CpRe(NO){P(Me)(Ph)(C 10 H 8 N)}]BF 4 [( R Re , S P / S Re , R P )‐ 10 , ( R Re , R P / S Re , S P )‐ 10 and ( R Re , S P )‐ 10 ]. The chelate ring was opened with NaSH to produce the hydrosulfido complexes [CpRe(NO){P(Me)(Ph)(C 10 H 8 N)}(SH)] [( R Re , S P / S Re , R P )‐ 11 , ( R Re , R P / S Re , S P )‐ 11 and ( R Re , S P )‐ 11 ]. Each step in this sequence proceeded with retention of configuration at rhenium. Complex 11 underwent acid‐promoted condensation with aldehydes to give thioaldehyde complexes [CpRe(NO){P(Me)(Ph)(C 10 H 8 N)}(S=CHR)]BF 4 ( 12a – d , R = Ph, Me, 4‐C 6 H 4 OMe, C 6 F 5 ). The addition of nucleophiles X – to 12a gave rhenium‐coordinated α‐chiral thiolate complexes [CpRe(NO){P(Me)(Ph)(C 10 H 8 N)}{SC(H)(Ph)(X)}] ( 13a – e , X = acac, PhCH 2 S, EtS, t BuS, CN) with 42–89 % de . The thiolate can readily be cleaved from the rhenium complex by a methylation/chelate ring‐closure strategy. The stereochemistry of the entire reaction sequence was corroborated for each step by X‐ray crystallography.