Preparation of new classes of aliphatic, allylic, and benzylic zinc and copper reagents by the insertion of zinc dust into organic halides, phosphates, and sulfonates
作者:Carole Jubert、Paul Knochel
DOI:10.1021/jo00046a026
日期:1992.9
The insertion of zinc dust into primary alkyl chlorides, bromides, phosphates, and sulfonates in a polar solvent (DMPU, DMA) and in the presence of a catalytic amount of LiI (0.2 equiv) provides new organozinc reagents of the type RZnX (X = Cl, Br, OSO2R, OP(O)(OR)2) in excellent yields. After the transmetalation to the corresponding copper reagent RCu(CN)ZnX using CuCN.2LiCl, the addition of electrophiles, such as Michael acceptors, affords the desired adducts. Similarly, various new allylic and benzylic zinc reagents were prepared without the formation of any Wurtz-coupling side product and reacted with various electrophiles.
Pd-catalyzed nucleophilic allylic alkylation of aliphatic aldehydes by the use of allyl alcohols
Under catalysis of Pd(OAc)2-(P-n-Bu)3, Et2Zn promotes a variety of allyl alcohols to undergo nucleophilic allylation of aliphatic aldehydes and ketones at room temperature and provides homoallyl alcohols in 60–90 and ca. 60% isolated yield, respectively. The reaction is irreversible and kinetically controlled, and unique regio- and stereoselectivities observed for the allylation with unsymmetrically