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.
Preparation of highly functionalized magnesium, zinc, and copper aryl and alkenyl organometallics via the corresponding organolithiums
作者:Charles E. Tucker、Tahir N. Majid、Paul Knochel
DOI:10.1021/ja00036a060
日期:1992.5
Preparation of polyfunctional olefins and allenes using 1,1-bimetallics of zinc and zirconium
作者:Charles E. Tucker、Bjoern Greve、Wolfram Klein、Paul Knochel
DOI:10.1021/om00013a020
日期:1994.1
The hydrozirconation of various alkenylzinc halides with Cp2Zr(H)Cl in dry dichloromethane provides 1,1-dimetalloalkanes of zinc and zirconium which react with aldehydes, providing (E)-alkenes with good to excellent stereoselectivity (up to 98% E). The reaction tolerates the presence of a wide range of functionalities in the dimetallic species as well as in the aldehyde, allowing the preparation of functionalized olefins. Ketones can also be olefinated by these reagents. However, only a moderate stereoselectivity is observed. The hydrozirconation of alkynylzinc halides with CP2Zr(H)Cl gives 1,1-dimetalloalkenes of zinc and zirconium which react with aldehydes, affording allenes. The olefination of alpha,beta-unsaturated aldehydes provides a short access of 1,2,4-trienes.
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
Treatment of (E)-alk-1-enyldicyclohexylboranes with tributyltin methoxide in the presence of galvinoxyl (1 mol%) at room temperature results in transfer of the alk-1-enyl group from boron to tin to give (E)-alk-1-enyltributylstannanes in a highlystereoselective fashion. Subsequent halodestannylation of (E)-alk-1-enyltributylstannanes is allowed to proceed in a one-pot manner to produce the corresponding