Other palladium-catalyzed cross-coupling reactions

These Diels-Alder reactions were performed in dichloromethane, but the efficiency of imidazolium salts as Lewis acid catalysts suggested that ionic liquids could improve the rate of such transformations. Indeed, Diels-Alder reactions result in greater stereoselectivity when performed in a 5M solution of LiClOq in diethyl ether. 

Microencapsulated Sc(OTf)3 was used as the catalyst, allowing clean isolation of the product from the reaction mixture by extraction with diethyl ether. The ionic liquid containing the Lewis acid was repeatedly reused.  

---

The generally accepted catalytic cycle for the Buchwald-Hartwig amination mirrors that of other palladium catalyzed cross-coupling reactions.10 11 irThere is an oxidative addition (A to B), followed by an exchange on palladium (B to C), and finally a reductive elimination (C to D and A). The main difference involves the exchange step. In a Suzuki, or Stille, reaction this step proceeds through a discrete transmetallation event, whereas... 

Alkenyliodonium salts have been used as highly reactive reagents for Heck-type olefination [39, 971], Sonogashira-type coupling with alkynes [965, 972] and similar other palladium-catalyzed cross-coupling reactions [966, 973, 974]. In a specific example, (Z)-p-fiuoro-a,p-unsaturated esters 721 were stereoselec-tively synthesized from (Z)-2-fluoro-l-alkenyliodonium salts 720 by the Pd-catalyzed methoxycarbonylation reaction (Scheme 3.288) [974]. This reaction proceeds at room temperature and is compatible with various functional groups on the substrate. 

Compared to other palladium-catalyzed cross-coupling reactions such as Stille and Suzuki, mechanistic proposals on the transmetalation step in... 

Palladium-catalyzed cross-coupling reactions are not restricted to stannane derivatives, however, and other azaheterocyclic carbanion derivatives to have been investigated include l-methyl-2-pyrrolylmagnesium bromide and l-methyl-2-pyrrolylzinc chloride (81TL5319), l-methyl-2-indolymagnesium bromide (81TL5319), l-substituted-2- and 5-imidazolyl-... 

Scheme8.5. Palladium-catalyzed cross-coupling reactions of stannanes and other carbon nucleophiles with aryl, allyl, and vinyl bromides [56, 69-72],...

Other interests in the area of phosphorus acids and their derivatives has centered on the following subjects synthesis of new ligands and catalysts for known reactions, synthesis of supramolecular logic gates, use of phosphates as electrophiles in palladium-catalyzed cross-coupling reactions, synthesis of phosphate based dendrimers and conjugates with oligosaccharides. 

---