Extensive Isomerization of Alkenes Using a Bifunctional Catalyst:  An Alkene Zipper

Abstract

Redox isomerizations are examples of atom-economical processes 1 in which one site in an organic substrate is oxidized with concomitant reduction of another site. One especially well-studied example is the conversion of allylic alcohols to aldehydes or ketones, 2,3 which involves movement of the alkene double bond 4-7 over two positions (eq 1, n) 2). Far fewer catalysts exist for the movement of a more remote double bond (n > 2). For example, Kirchner et al. reported 8 that, although [CpRu(PR 3)(CH 3 CN) 2 ] + (1a-1c) were improved catalysts for allylic alcohol isomerization relative to CpRu(PR 3) 2 Cl, it failed in the case of 3-buten-1-ol (n) 3) or alkenes devoid of alcohol functionality. The apparent record for alkene isomerization of any kind is over 20 positions on the hydrocarbon CH 3 (CH 2) 19 CHdCH(CH 2) 19 CH 3 by stoichiometric amounts of the reagent Cp 2 Zr(H)(Cl). 9 The apparent record for catalyzed double bond movement is on 9-decene-1-ol (nine positions, n) 9) using Fe 3 (CO) 12. 10,11 However, 30 mol % was required, which means that nearly a mole of metal was used per mole of alkenol.

Alkene Isomerisation Catalysed by a Ruthenium PNN Pincer Complex

“…[37] One of the most active catalysts is the ruthenium-based "alkene zipper" developed by Grotjahn and co-workers. [38,39] Recently, researchers have focused on the selectivity of the alkene isomerisation. Beller and Grotjahn have developed catalysts which allow a selective one-position shift of the double bond with high selectivity for E isomers, [27,40] whereas other groups focused on the synthesis of the less thermodynamically favoured Z isomers.…”

Broad‐Spectrum Catalysts for the Ambient Temperature Anti‐Markovnikov Hydration of Alkynes

“…Aldehydes derived from enynes (2 w-2 aa), including a conjugated enyne (2 aa), could be effectively prepared using this catalyst (80-96 %). Complexes related to 5 and 6 are remarkably active catalysts for the isomerization of terminal alkenes [15] whereas isomerization of the terminal alkene in 2 w is not observed using the catalyst derived from 9 and 11 n. In addition, the dial 2 ab is formed in 87 % yield from the corresponding diyne. It is also noteworthy that b-amino or b-hydroxy aldehydes could be prepared with this catalyst (2 ac-2 af, 76-96 %).…”

Catalysis of Selective Hydrogen/Deuterium Exchange at Allylic Positions Using Deuterium Oxide

“…D 2 O had a deuterium content of 99.9% and was stored and used in the glovebox to avoid dilution with atmospheric moisture. Preparation of 1 [22] and reaction conditions and experiment setup have been described elsewhere [16]. Homogeneous reactions were carried out in resealable J.…”