Ligand thiol

Hydroxy groups can be introduced by hydrolysis of chlorometal phthalocyanines. The hydroxy groups may be replaced by thiol ligands. 

Liaw et al. reported that conversions between the neutral sparteine [Fe(NO)2] complex 133 and the anionic Fe(NO)2 [Fe(NO)2(S2C3Hg)] 137 proceed via the cationic sparteine Fe(NO)2 -complex 135 through oxidation by NO" " and transfer of the [Fe(NO)2] -unit to the chelating ligand S-(CH2)3-S 136 (Scheme 35). The resulting anionic complex 137 is stable in contrast to the cationic complex 135. The cationic complex 135 also acts as a [Fe(NO)2] donor in the presence of the DNIC [(PhS)2Fe(NO)2] 138 to yield Roussin s red ester 139. The bidentate thiol ligand S-(CH2)3-S 136 promotes the stability of the anionic DNIC Fe(NO)2 ... 

Scheme 2.31 Ni-catalysed 1,4-addition of ZnEt2 to chalcone with bidentate thiol ligands.

Other excellent results have been reported by Kang et al. for the addition of ZnEt2 to aldehydes by using chiral cyclic amino thiol ligands depicted in Scheme 3.7. A total enantioselectivity was obtained when (lR,25)-l-phenyl-2-piperidinopropane-1-thiol was used as the ligand in the reactions of substituted benzaldehydes. However, -hexanal and traw -cinnamaldehyde could only be... 

Scheme 3.7 Cyclic amino thiol ligand for additions of ZnEt2 to aldehydes.

On the other hand, novel diastereomeric p-amino thiol ligands possessing an isoquinuclidine skeleton have been readily prepared by Hongo et al. via imino-Diels-Alder reactions.As shown in Scheme 3.15, when applied to the enantioselective addition of ZnEt2 to various aldehydes, one of these ligands afforded the products with high enantioselectivities of up to 94% ee. 

In the same area, these authors have also tested a p-amino thiol ligand containing a bicyclo[2.2.1] ring system, the 2-azanorbornylmethanethiol, which gave... 

Scheme 3.16 P-Amino thiol ligand based on bicycle[2.2.1] ring system and its P-amino alcohol analogue for additions of ZnEt2 to aldehydes.

Scheme 3.62 Zirconocene-ziiic transmetalations and in situ additions to aldehydes in the presence of amino thiol ligand.

In 2004, Yang and Tseng reported the synthesis of a series of new chiral amino thiol ligands derived from L-valine, which were further employed (1 mol%) in the enantioselective alkenylzinc addition to aldehydes, providing an efficient route for chiral ( )-allylic alcohols with enantioselectivities of up to >99% ee, as shown in Scheme 3.67. ... 

Scheme 3.67 Amino thiol ligand for additions of alkenylzinc reagents to aldehydes.

Complexes with sulfido and monodentate thiol ligands 322... 

Complexes with thioether and mixed thioether/thiol ligands 326... 

Instead of the amide thiol ligands themselves, their S-protected precursors are sometimes used. If the protecting groups are not removed before or during complexation, thioether sulphur is present in the donor set. This confers different... 

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