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Synthesis of Chiral Rhenium Complexes Containing Functionalized Thiolate Ligands
Author(s) -
Burzlaff Nicolai,
Schenk Wolfdieter A.
Publication year - 1998
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/(sici)1099-0682(199812)1998:12<2055::aid-ejic2055>3.0.co;2-2
Subject(s) - chemistry , diastereomer , sodium ethoxide , rhenium , medicinal chemistry , ligand (biochemistry) , base (topology) , sodium carbonate , sodium , yield (engineering) , acetonitrile , stereochemistry , inorganic chemistry , organic chemistry , mathematical analysis , biochemistry , materials science , receptor , mathematics , ethanol , metallurgy
Chiral racemic rhenium thiolate complexes [CpRe(NO)(PPh 3 )(SR)] were obtained under either acidic or basic conditions. Thus, when [CpRe(NO)(PPh 3 )(CH 3 )] ( 1 ) was treated with etheral HBF 4 and HSR the thiolate complexes [CpRe(NO)(PPh 3 )(SR)] [SR = SCH 2 (2‐furyl) ( 2 ), SCH 2 C(O)OEt ( 3 )] were obtained after chromatographic workup. Ligand exchange reactions between [CpRe(NO)(PPh 3 )(OC 4 H 8 )]BF 4 ( 4 ) and sodium thiolates yielded analogous complexes with SR = SH ( 5 ), SCH 2 CH 2 Ph ( 6 ), SCH 2 CH=CH 2 ( 7 ). SR groups which tolerate strongly alkaline conditions may be introduced by treatment of 4 with HSR in the presence of sodium ethoxide as demonstrated by the high‐yield synthesis of 2 as well as of complexes with SR = SCH 2 CH 2 NHAc ( 8 ), SCH 2 CH 2 C(O)OH ( 9 ). A milder synthesis using hydrated sodium carbonate as a base provided 8 and compounds with SR = SCH 2 CH 2 C(O)OMe ( 10 ), SCH 2 CH 2 C(O)NHCH 2 Ph ( 11 ) in high yields. Using similar methods, thiolate complexes of ( R )‐ N ‐acetylcysteine ( 13 ), its methyl ester ( 14 ), ( R )‐ N ‐phthaloylcysteine ( 16 ), and N ‐[( S )‐3‐mercapto‐2‐methylpropionyl]‐ S ‐proline (Captopril) ( 17 ) were obtained as diastereomeric pairs. The formation of 13 was preceded by the O‐bonded isomer 12 which slowly rearranges in solution. 13 can be converted under acidic conditions into its methyl ( 14 ) or ethyl ( 15 ) esters. The diastereomers of 16 were separated by crystallization, and the structure of the ( R , R )‐isomer 16a determined.