Organotin compounds with alkenyl halides

For example, with the organotin compound having hetero atoms the transmetalation proceeds easily by the stabilization effects of hetero atoms. Then, the lithium compounds react with alkenyl halides and are hydrolyzed to give naturally obtainable 9-hydroxydendrolasin [75]. 

Stille coupling was also developed in tlie early 1980s and is similar to Suzuki coupling in its sequence. It is used to couple aryl or vinyl halides or triflates with organotin compounds via oxidative addition, transmetallation, and reductive elimination. The oxidative addition reaction has tlie same requirements and preferences as discussed earlier for tlie Heck and Suzuki reactions. The reductive elimination results in formation of tlie new carbon-carbon bond. The main difference is that tlie transmetallation reaction uses an organotin compound and occurs readily without the need for an oxygen base. Aryl, alkenyl, and alkyl stannanes are readily available. Usually only one of tlie groups on tin enters into... 

As organotin compounds (organostannanes) undergo smooth Pd-catalysed transmetallation, aryl halides react with a wide variety of aryl-, alkenyl- and alkylstannanes [139]. Coupling with allylstannane is the first example [140]. The reaction is called the Migita-Kosugi-Stille or Stille coupling. Aryl, alkenyl, allyl, alkynyl and benzyl... 

The cross-coupling reaction of alkenyl(fluoro)silanes with aryl halides sometimes produces, in addition to the desired ipso-cowpled products, small amounts of cmc-coupled products [14]. The czne-coupling is often striking in the reaction with organotin compounds. The isomer ratio of products produced by the reaction of l-fluoro(dimethyl)silyl-l-phenylethene with aryl iodides is found to depend on the electronic nature of a substituent on aryl iodides (Eq. 11) an electron-withdrawing group like trifluoromethyl and acetyl favors the formation of the ipso-coupled product. To explain the substituent effect, the mechanism depicted in Scheme 3 is proposed for the transmetalation of alkenylsilanes with palladium(ll) complexes. It is considered that an electron-donating substituent on Ar enhances... 

Pd-catalyzed coupling of aryl or alkenyl halides and triflates with organotin compounds also takes place smoothly to produce the coupling products, which was discovered by Shlle and Kosugi independently and developed by a number of research groups (Eqs. 5.24 and 25) [100-103],... 

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