We report palladium-catalyzed cross-couplingreactions of chiral secondary non-stabilized dialkylzinc reagents, prepared from readily available chiral secondary alkyl iodides, with alkenyl and aryl halides. This method provides α-chiral alkenes and arenes with very high retention of configuration (dr up to 98:2) and satisfactory overall yields (up to 76 % for 3 reaction steps). The configurational stability
Preparation of polyfunctional aryl and alkenyl zinc halides from functionalized unsaturated organolithiums and their reactivity in cross-coupling and conjugated addition reactions
作者:Ingo Klement、Mario Rottländer、Charles E. Tucker、Tahir N. Majid、Paul Knochel、Patricia Venegas、Gérard Cahiez
DOI:10.1016/0040-4020(96)00246-3
日期:1996.5
organolithiums which are stable for a short time at these low temperatures and can be transmetalated to organozinc derivatives by the addition of zinc bromide. The resulting unsaturated organozinc halides can then be warmed up and are perfectly stable at 25 °C. They react directly with tosyl cyanide. In the presence of CuCN·2LiCl, they add in a Michael-fashion to alkylidenemalonates. In the presence
Addition of polyfunctional and pure (E or Z) alkenylcopper and arylcopper compounds to alkylidenemalonates
作者:G�rard Cahiez、Patricia Venegas、Charles E. Tucker、Tahir N. Majid、Paul Knochel
DOI:10.1039/c39920001406
日期:——
Polyfunctional and stereochemically pure (E) or (Z) alkenylcopper reagents have been generated by carbocupration of terminal alkynes or by an iodine–lithium exchange reaction and have been found to add to various diethyl alkylidenemalonates, affording γ,δ-unsaturated esters in excellent yields.