Synthesis and Catalytic Properties of Configurationally Stable and Non-racemic Sulfur-Containing Palladacycles
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- 作者：Jairton Dupont ; Adriane S. Gruber ; Glé ; dison S. Fonseca ; Adriano L. Monteiro ; Gunter Ebeling ; and Robert A. Burrow
- 刊名：Organometallics
- 出版年：2001
- 出版时间：January 8, 2001
- 年：2001
- 卷：20
- 期：1
- 页码：171 - 176
- 全文大小：82K
- 年卷期：v.20,no.1(January 8, 2001)
- ISSN：1520-6041
文摘
Racemic sulfur chloro-bridged palladacycles (rac-4b-6b), derived from the orthopalladationof (1-tert-butylsulfanylethyl)benzene, (1-methylsulfanylethyl)benzene, and 2-(1-tert-butylsulfanylethyl)naphthalene (rac-1-3), have been synthesized in good yields using palladiumacetate as the metalation agent and followed by reaction with LiCl. Palladacycles rac-4band rac-6b have been isolated as single isomers, whereas rac-5b has been obtained as amixture of two diastereoisomers (3:1). Variable-temperature 1H NMR showed that theS-t-Bu palladacycle 4b is configurationally stable over a large range of temperatures (from-20 to 100 
C). On the other hand, S-Me analogue 5b undergoes facile sulfur pyramidalinversion with an energy barrier of 18 kcal/mol. Moreover, the optically active (1-alkylsufanylethyl)benzenes, (R)-1 and (R)-2, respectively, have been prepared in 91% and 97%ee, respectively, from the reaction of sodium methylthiolate and sodium tert-butylthiolate, respectively, with non-racemic (S)-(-)-1-phenylethanol (93-99% ee). The reactionof (1-alkylsufanylethyl)benzenes (R)-1 and (R)-2 with palladium acetate in acetic acid at 90C affords the corresponding orthopalladated compound (R,R)-4a and (R,R and R,S)-5a,respectively. The molecular structure of the acetato-bridged dimer (R,R)-4a has beendetermined by means of an X-ray diffraction analysis. The palladacycle (R,R)-4b has shownto be excellent catalyst precursor, in terms of catalytic activity, for the arylation of 3,4-dihydro-2H-pyrane under mild reaction conditions, however without any asymmetricinduction.
C). On the other hand, S-Me analogue 5b undergoes facile sulfur pyramidalinversion with an energy barrier of 18 kcal/mol. Moreover, the optically active (1-alkylsufanylethyl)benzenes, (R)-1 and (R)-2, respectively, have been prepared in 91% and 97%ee, respectively, from the reaction of sodium methylthiolate and sodium tert-butylthiolate, respectively, with non-racemic (S)-(-)-1-phenylethanol (93-99% ee). The reactionof (1-alkylsufanylethyl)benzenes (R)-1 and (R)-2 with palladium acetate in acetic acid at 90C affords the corresponding orthopalladated compound (R,R)-4a and (R,R and R,S)-5a,respectively. The molecular structure of the acetato-bridged dimer (R,R)-4a has beendetermined by means of an X-ray diffraction analysis. The palladacycle (R,R)-4b has shownto be excellent catalyst precursor, in terms of catalytic activity, for the arylation of 3,4-dihydro-2H-pyrane under mild reaction conditions, however without any asymmetricinduction.