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m ‐Metallaphenol: Synthesis and Reactivity Studies
Author(s) -
Han Feifei,
Wang Tongdao,
Li Jinhua,
Zhang Hong,
Xia Haiping
Publication year - 2014
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201304957
Subject(s) - chemistry , electrophile , reactivity (psychology) , medicinal chemistry , nucleophile , annulation , pyridine , triethylamine , osmium , stereochemistry , thiocyanate , organic chemistry , medicine , alternative medicine , pathology , ruthenium , catalysis
Treatment of the osmium complex [Os{CHC‐(PPh 3 )CH(OH)‐ η 2 ‐C≡CH}(PPh 3 ) 2 (NCS) 2 ] ( 1 ) with excess triethylamine produces the first m ‐metallaphenol complex [Os{CHC(PPh 3 )CHC(OH)CH}(PPh 3 ) 2 (NCS) 2 ] ( 2 ). The NMR spectroscopic and structural data as well as the nucleus‐independent chemical‐shift (NICS) values suggest that osmaphenol 2 has aromatic character. The reactivity studies demonstrate that 2 can react with different isocyanates to form the annulation reaction products [Os{CHC(PPh 3 )CHC(OCONR)C}(PPh 3 ) 2 (NCS) 2 ] (R=Ph ( 3 ), i Pr ( 7 ), Bn ( 8 )) via the carbamate intermediates [Os{CHC(PPh 3 )CHC(O‐CONHR)CH}(PPh 3 ) 2 (NCS) 2 ] (R=Ph ( 4 ), i Pr ( 5 ), Bn ( 6 )). In addition, the similar annulation reactions can be extended to other unsaturated compounds containing N–C multiple bonds, for example, isothiocyanates, pyridine, and sodium thiocyanate, which can produce the corresponding fused osmabenzene complexes. In contrast, the reactions of 2 with common electrophiles, such as NOBF 4 , NO 2 BF 4 , N ‐bromosuccinimide, and N ‐chlorosuccinimide only led to the decomposition of the metallaphenol ring. The experimental results suggest that 2 is very electrophilic and readily reacts with nucleophiles, which is mainly due to the metal center and the strong electron‐withdrawing phosphonium group.