Cyclooligomerization with Transition Metal Catalysts

Abstract

This report is concerned not only with the syntheses of new ring systems and the preparation of derivatives of known rings but also with new types of catalysts based upon, e.g., nickel, iron, molybdenum, manganese, and palladium. The broad applicability of the methylene insertion reaction as a method for identifying monoand di-methyl-substituted eight-, ten-, and twelve-,membered rings is also demonstrated. A further section is concerned with the possible mechanism of C-C bond formation in transition metal complexes; several earlier suggestions have been revised in the light of new experimental data. In addition, experimental results are discussed which indicate that the reactivity and selectivity of the complexes formed by the nickel-ligand catalyst and olefins or alkynes depend upon the structure of the ligands. A number of interesting syntheses have likewise been carried out starting from cis-1,2-divinyIcyclobutane. A few examples are shown in eq. (62)['641. 0s: 1 + COOR -COOH J COOR ROOC COOR COOR COOR 0 I wish to express tit!' thanks, also on behalf ofmy co-workers, to the Director of the Max-Planck-Institut f iir Kohlenforsckung ProJ Dr. G. Wilke for his support of our work and for many useful suggestions. In particular I gratefully acknowledge continuingfinancial and academic support even after my acceptance of a position at the Gesamtkochsckule Essen. I also wish to acknowledge the friendly assistance

An Approach to Mimicking the Sesquiterpene Cyclase Phase by Nickel-Promoted Diene/Alkyne Cooligomerization

“…12,33–35 Utilizing dienes, Wilke and coworkers have established methods for the creation of 4, 36–38 5, 39–41 6, 42 8, 36–38 10, 43–45 12, 46 and >12-membered rings 12,47 (Scheme 2A). In particular, the synthesis of 10-membered ring systems by cooligomerization with a C 2 component, either alkenes 48,49 or alkynes, 44,45,50,51 has been developed in great detail ( vide infra ).…”

Remarkable features of intermediates in the early transition metal catalyzed conversion of monosubstituted alkenes, dienes and alkynes

“…CATALYTIC CYCLODIMERIZATION OF ISOPRENE The following three types of cyclic dimers (each with a 4, 6 and 8 membered ring) have been prepared from isoprene by catalytic reactions using a series of transition metal complexes. The preparation of 9, which is converted readily to 13 by sigmatropic rearrangement, was achieved with Ni(COD)2/P(OC6H4Ph) 3 under 9 10 11 12 13 379 mild conditions [56]. Titanium complexes bearing appropriate donors lead to the preferential production of the cyclohexene derivative I0 while iron cata-~~ lysts [58] usually form the isomer II (Table V).…”

“…These systems also catalyze the codimerization of isoprene with 2,3-dimethylbutadiene to give 1,2,5,10-tetramethyl-l,5,9-cyclododecatriene in 85% selectivity, and the codimerization of isoprene with butadiene to give l-methyl-l,5,9-cyclododecatriene in 65% selectivity. The corresponding reaction to give l-methyl-l,5,9-cyclododecatriene is also possible with the use of Ni catalysts (85% selectivity) [56]. Acyclic alkyne trimerization was recently achieved using the ruthenium cluster [Ru3(CO)8-(HC2tBu)3] [77].…”

Catalytic Cyclooligomerization of Enones with Three Methylene Equivalents

“…1 The potential value of these reactions derives from their ability to directly assemble cyclic molecules from the repeated coupling of a simple building block. However, this same feature introduces a significant challenge associated with controlling ring-size selectivity.…”