15469-98-4Relevant academic research and scientific papers
Ruthenium-catalyzed propargylic substitution reactions of propargylic alcohols with oxygen-, nitrogen-, and phosphorus-centered nucleophiles
Nishibayashi, Yoshiaki,Milton, Marilyn Daisy,Inada, Youichi,Yoshikawa, Masato,Wakiji, Issei,Hidai, Masanobu,Uemura, Sakae
, p. 1433 - 1451 (2005)
The scope and limitations of the ruthenium-catalyzed propargylic substitution reaction of propargylic alcohols with heteroatom-centered nucleophiles are presented. Oxygen-, nitrogen-, and phosphorus-centered nucleophiles such as alcohols, amines, amides, and phosphine oxide are available for this catalytic reaction. Only the thiolate-bridged diruthenium complexes can work as catalysts for this reaction. Results of some stoichiometric and catalytic reactions indicate that the catalytic propargylic substitution reaction proceeds via an allenylidene complex formed in situ, whereby the attack of nucleophiles to the allenylidene Cγ atom is a key step. Investigation of the relative rate constants for the reaction of propargylic alcohols with several para-substituted anilines reveals that the attack of anilines on the allenylidene Cγ atom is not involved in the rate-determining step and rather the acidity of conjugated anilines of an alkynyl complex, which is formed after the attack of aniline on the C γ atom, is considered to be the most important factor to determine the rate of this catalytic reaction. The key point to promote this catalytic reaction by using the thiolate-bridged diruthenium complexes is considered to be the ease of the ligand exchange step between a vinylidene ligand on the diruthenium complexes and another propargylic alcohol in the catalytic cycle. The reason why only the thiolate-bridged diruthenium complexes promote the ligand exchange step more easily with respect to other monoruthenium complexes in this catalytic reaction should be that one Ru moiety, which is not involved in the allenylidene formation, works as an electron pool or a mobile ligand to another Ru site. The catalytic procedure presented here provides a versatile, direct, and one-step method for propargylic substitution of propargylic alcohols in contrast to the so far well-known stoichiometric and stepwise Nicholas reaction.
Ferrocenium hexafluorophosphate as an inexpensive, mild catalyst for the etherification of propargylic alcohols
Queensen, Matthew J.,Rabus, Jordan M.,Bauer, Eike B.
, p. 221 - 229 (2015/08/06)
Commercial ferrocenium hexafluorophosphate ([FeCp2]PF6) was found to be an efficient catalyst for the etherification of terminal, tertiary propargylic alcohols with primary and secondary alcohols (5 h to 3 days reaction time at 40 °C in CH2Cl2, 3 mol% catalyst loading). The propargylic ether products were isolated in 90-20% yields. The alcohols and propargylic alcohols were employed in an equimolar amount and no further additives were required. For a purely aromatic propargylic alcohol, the isolated yields were lower than those for a mixed aromatic-aliphatic propargylic alcohol. Through monitoring reactant consumption and product formation over time, we found that the aromatic propargylic alcohol undergoes yield-diminishing Meyer-Schuster rearrangements to the aldehyde more easily than the mixed aromatic-aliphatic propargylic alcohol. The employment of [Fe(Cp)2]PF6 as a single electron oxidant has the potential to add a new direction in the development of catalysts for the title reaction based on single electron transfer processes.
Propargylic substitution reaction catalyzed by group IV(Ti, Zr, Hf)-Ru heterobimetallic complexes
Miyazaki, Takamasa,Tanabe, Yoshiaki,Yuki, Masahiro,Miyake, Yoshihiro,Nishibayashi, Yoshiaki
experimental part, p. 3194 - 3199 (2011/07/31)
A series of heterobimetallic complexes consisting of group IV metallocenyl diphosphines and Ru were synthesized and structurally characterized. Most of them work as catalysts toward propargylic substitution reaction of 1,1-diphenyl-2-propyn-1-ol (4) with EtOH. The stoichiometric reactions of the heterobimetallic complexes [MCl2(μ-η5: η1-C5H4PEt2) 2RuClCp*] (M = Zr, Hf) with 4 and NaBArF4 afforded key reactive intermediate allenylidene complexes [MCl2(μ- η5:η1-C5H4PEt 2)2RuCp*(=C=C=CPh2)]BArF 4, whose molecular structures were confirmed by X-ray analyses. A plausible reaction pathway for the catalytic reaction is proposed where group IV metal chloride and Ru moieties work cooperatively.
Copper(II) bromide catalyzed novel preparation of propargylic ethers and sulfides by SN1-type substitution between propargylic alcohols and alcohols or thiols
Hui, Hao-Hao,Zhao, Qin,Yang, Ming-Yu,She, De-Bing,Chen, Min,Huang, Guo-Sheng
, p. 191 - 196 (2008/12/20)
A general and efficient copper(II) bromide catalyzed substitution reaction of propargylic alcohols with carbon and heteroatom-centered nucleophiles, such as alcohols and thiols, leading to the construction of C-O and C-S bonds has been developed. High pro
