2- Thienyl copper lithium

Thienyl(cyano)copper lithium S Cu(CN)Li xhe reagent is obtained by reaction of thiophene with BuLi in THF at - 78° and then with CuCN at - 40°. The reagent is fairly stable and can be stored in THF at - 20° for about 2 months. It is inert, but is readily converted by addition of RLi or RMgX into a higher-order mixed cuprate, which is as efficient as the freshly prepared cuprate."1... 

The reaction of thienyllithium with organic halides to form C—C bonds has been discussed in Section 2.10.4.7.2. This cannot, however, be extended to aryl, alkenyl or heteroaryl halides in which the halogen is attached to an sp carbon. Such cross-coupling can be successfully achieved by nickel or palladium-catalyzed reaction of the unsaturated organohalide with a suitable thienyl metal derivative. The metal is usually zinc, magnesium, boron or tin occassionally lithium, mercury, copper, and silicon derivatives of thiophene have also found application in such reactions. In addition to this type, the Pd-catalyzed reaction of halogenated thiophenes with suitable alkenes and alkynes, usually referred to as the Heck reaction, is also discussed in this section. Besides these, a few other miscellaneous Pd-catalyzed substitution reactions on thiophene will also be referred to. 

Lithium 2-Thienylcyanocuprate-Based Copper 223 Table 5.6 1,4-Conjugate addition reactions with thienyl-based organocopper reagents. 

Kiyotsuka Y, Kobayashi Y (2010) Highly efficient substitution of allylic picolinates with copper reagents derived from aryl-, alkenyl-, furyl-, and thienyl-lithiums. Tetrahedron 66 676-684... 

Immobilized zincates such as 177 can be prepared by treating serine-bound 4-iodobenzoate with t-BujZnLi at 0°C. They react readily with aldehydes. Transme-tallation with lithium (2-thienyl)cyanocuprate provides the copper species 178 that undergoes 1,4-additions. Lithium trialkylzincates can be used for the preparation of benzylic zinc reagents using a very elegant approach of Harada. Thus, the treat-... 

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