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Chiral diphosphine derivatives of alkylidyne tricobalt carbonyl clusters - A comparative study of different cobalt carbonyl (pre)catalysts for (asymmetric) intermolecular Pauson-Khand reactions

Mottalib, Abdul LU ; Haukka, Matti and Nordlander, Ebbe LU (2016) In Polyhedron 103. p.275-282
Abstract
Reaction of the tricobalt carbyne cluster [Co-3(mu(3)-CH)(CO)(9)] with chiral diphosphines of the Josiphos and Walphos families affords the new clusters [Co-3(mu(3)-CH)(CO)(7)(P-P*)] in good yield (P-P* = J004 (1), J005 (2), J007 (3), W001 (4), W003 (5)). The new alkylidyne tricobalt clusters, and the previously known [Co-3(mu(3)-CH)(CO)(7)(mu-J003)], have been tested as catalysts/catalyst precursors for intermolecular Pauson-Khand cyclization, using norbornene and phenylacetylene as substrate. The diphosphine-substituted tricobalt carbonyl clusters proved to be viable catalysts/catalyst precursors that gave products in moderate to good yields, but the enantiomeric excesses were low. When the chiral diphosphine ligands were used as... (More)
Reaction of the tricobalt carbyne cluster [Co-3(mu(3)-CH)(CO)(9)] with chiral diphosphines of the Josiphos and Walphos families affords the new clusters [Co-3(mu(3)-CH)(CO)(7)(P-P*)] in good yield (P-P* = J004 (1), J005 (2), J007 (3), W001 (4), W003 (5)). The new alkylidyne tricobalt clusters, and the previously known [Co-3(mu(3)-CH)(CO)(7)(mu-J003)], have been tested as catalysts/catalyst precursors for intermolecular Pauson-Khand cyclization, using norbornene and phenylacetylene as substrate. The diphosphine-substituted tricobalt carbonyl clusters proved to be viable catalysts/catalyst precursors that gave products in moderate to good yields, but the enantiomeric excesses were low. When the chiral diphosphine ligands were used as promoters/auxiliary ligands for the same Pauson-Khand reaction, using either [Co-2(CO)(8)] or [Co-4(CO)(12)] as catalyst precursors, both the overall yields and the selectivities with respect to cyclopentenone formation were significantly improved. The best results were obtained for ligands J007 and W001, with [Co-4(CO)12] as pre-catalyst, where yields of 96%, and virtually 100% selectivity were obtained. However, the enantioselectivity of product formation was low or non-existent. The crystal structure of [Co-3(mu(3)-CH)(CO)(7)(mu-J004)] is described. [J003 = [(R)-1-{(S)-2-(dicyclohexylphosphino)-ferrocenyl} ethyldicyclohexylphosphine], J004 = [(R)-1-{(S)-2-(dicyclohexylphosphino)-ferrocenyl} ethyldiphenylphosphine], J005 = [(R)-1-{(S)-2-(diphenylphosphino)ferrocenyl}ethyl-di-3,5-xylylphosphine], J007 = [(R)-1-{(S)-2-di-(4-methoxy-3,5-dimethylphenyl)phosphino)ferrocenyl) ethyldicyclohexylphosphine], W001 = [(R)-1-{(R)-2-(2'-diphenyl phosphinophenyl)ferrocenyl} ethyldi(bis-3,5-trifluoromethylphenyl) phosphine], W003 [(R)-1-{(R)-2-(2'-diphenylphosphino-phenyl)ferrocenyl}ethyldi(3,5-xylyl)phosphine]. (C) 2015 Elsevier Ltd. All rights reserved. (Less)
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Contribution to journal
publication status
published
subject
keywords
Cluster, Chirality, Enantioselectivity, Pauson-Khand reaction, Catalysis
in
Polyhedron
volume
103
pages
275 - 282
publisher
Elsevier
external identifiers
  • wos:000367761400011
  • scopus:84949112992
ISSN
0277-5387
DOI
10.1016/j.poly.2015.04.021
language
English
LU publication?
yes
id
e6a9292f-5bcf-46c8-b478-ff0573c061b4 (old id 8747814)
date added to LUP
2016-02-23 10:33:31
date last changed
2017-10-29 04:05:18
@article{e6a9292f-5bcf-46c8-b478-ff0573c061b4,
  abstract     = {Reaction of the tricobalt carbyne cluster [Co-3(mu(3)-CH)(CO)(9)] with chiral diphosphines of the Josiphos and Walphos families affords the new clusters [Co-3(mu(3)-CH)(CO)(7)(P-P*)] in good yield (P-P* = J004 (1), J005 (2), J007 (3), W001 (4), W003 (5)). The new alkylidyne tricobalt clusters, and the previously known [Co-3(mu(3)-CH)(CO)(7)(mu-J003)], have been tested as catalysts/catalyst precursors for intermolecular Pauson-Khand cyclization, using norbornene and phenylacetylene as substrate. The diphosphine-substituted tricobalt carbonyl clusters proved to be viable catalysts/catalyst precursors that gave products in moderate to good yields, but the enantiomeric excesses were low. When the chiral diphosphine ligands were used as promoters/auxiliary ligands for the same Pauson-Khand reaction, using either [Co-2(CO)(8)] or [Co-4(CO)(12)] as catalyst precursors, both the overall yields and the selectivities with respect to cyclopentenone formation were significantly improved. The best results were obtained for ligands J007 and W001, with [Co-4(CO)12] as pre-catalyst, where yields of 96%, and virtually 100% selectivity were obtained. However, the enantioselectivity of product formation was low or non-existent. The crystal structure of [Co-3(mu(3)-CH)(CO)(7)(mu-J004)] is described. [J003 = [(R)-1-{(S)-2-(dicyclohexylphosphino)-ferrocenyl} ethyldicyclohexylphosphine], J004 = [(R)-1-{(S)-2-(dicyclohexylphosphino)-ferrocenyl} ethyldiphenylphosphine], J005 = [(R)-1-{(S)-2-(diphenylphosphino)ferrocenyl}ethyl-di-3,5-xylylphosphine], J007 = [(R)-1-{(S)-2-di-(4-methoxy-3,5-dimethylphenyl)phosphino)ferrocenyl) ethyldicyclohexylphosphine], W001 = [(R)-1-{(R)-2-(2'-diphenyl phosphinophenyl)ferrocenyl} ethyldi(bis-3,5-trifluoromethylphenyl) phosphine], W003 [(R)-1-{(R)-2-(2'-diphenylphosphino-phenyl)ferrocenyl}ethyldi(3,5-xylyl)phosphine]. (C) 2015 Elsevier Ltd. All rights reserved.},
  author       = {Mottalib, Abdul and Haukka, Matti and Nordlander, Ebbe},
  issn         = {0277-5387},
  keyword      = {Cluster,Chirality,Enantioselectivity,Pauson-Khand reaction,Catalysis},
  language     = {eng},
  pages        = {275--282},
  publisher    = {Elsevier},
  series       = {Polyhedron},
  title        = {Chiral diphosphine derivatives of alkylidyne tricobalt carbonyl clusters - A comparative study of different cobalt carbonyl (pre)catalysts for (asymmetric) intermolecular Pauson-Khand reactions},
  url          = {http://dx.doi.org/10.1016/j.poly.2015.04.021},
  volume       = {103},
  year         = {2016},
}