79186-29-1Relevant academic research and scientific papers
Synergistic N-Heterocyclic Carbene/Palladium-Catalyzed Reactions of Aldehyde Acyl Anions with either Diarylmethyl or Allylic Carbonates
Yasuda, Shigeo,Ishii, Takuya,Takemoto, Shunsuke,Haruki, Hiroki,Ohmiya, Hirohisa
, p. 2938 - 2942 (2018)
Benzylation and allylation of aldehyde acyl anions were enabled by the merger of a thiazolium N-heterocyclic carbene (NHC) catalyst and a palladium/bisphosphine catalyst in a synergistic manner. Owing to the mildness of the reaction conditions, various functional groups were tolerated in the substrates.
The Direct Conversion of α-Hydroxyketones to Alkynes
Ghiringhelli, Francesca,Nattmann, Lukas,Bognar, Sabine,Van Gemmeren, Manuel
, p. 983 - 993 (2019/01/24)
Alkynes are highly important functional groups in organic chemistry, both as part of target structures and as versatile synthetic intermediates. In this study, a protocol for the direct conversion of α-hydroxyketones to alkynes is reported. In combination with the variety of synthetic methods that generate the required starting materials by forming the central C-C bond, it enables a highly versatile fragment coupling approach toward alkynes. A broad scope for this novel transformation is shown alongside mechanistic insights. Furthermore, the utility of our protocol is demonstrated through its application in concert with varied α-hydroxyketone syntheses, giving access to a broad spectrum of alkynes.
Oxazolium Salts as Organocatalysts for the Umpolung of Aldehydes
Garapati, Venkata Krishna Rao,Gravel, Michel
supporting information, p. 6372 - 6375 (2018/10/15)
Oxazolium salts were successfully employed for the first time as organocatalysts for benzoin, Stetter, and redox esterification reactions. An N-mesityl oxazolium salt catalyzed homobenzoin reaction of aromatic, heteroaromatic, and aliphatic aldehydes delivered α-hydroxy ketones in high yields. This new type of catalyst proved remarkably effective for the Stetter reaction of challenging substrates such as β-alkyl-α,β-unsaturated ketones and electron-rich aromatic aldehydes in comparison to common thiazolium and triazolium salts.
Chemo- and Diastereoselective N-Heterocyclic Carbene-Catalyzed Cross-Benzoin Reactions Using N-Boc-α-amino Aldehydes
Haghshenas, Pouyan,Gravel, Michel
, p. 4518 - 4521 (2016/09/28)
N-Boc-α-amino aldehydes are shown to be excellent partners in cross-benzoin reactions with aliphatic or heteroaromatic aldehydes. The chemoselectivity of the reaction and the facial selectivity on the amino aldehyde allow cross-benzoin products to be obtained in good yields and good diastereomeric ratios. The developed method is utilized as the key step in a concise total synthesis of d-arabino-phytosphingosine.
Chemoselective N-heterocyclic carbene-catalyzed cross-benzoin reactions: Importance of the fused ring in triazolium salts
Langdon, Steven M.,Wilde, Myron M.D.,Thai, Karen,Gravel, Michel
supporting information, p. 7539 - 7542 (2014/06/10)
Morpholinone- and piperidinone-derived triazolium salts are shown to catalyze highly chemoselective cross-benzoin reactions between aliphatic and aromatic aldehydes. The reaction scope includes ortho-, meta-, and para-substituted benzaldehyde derivatives with a range of electron-donating and -withdrawing groups as well as branched and unbranched aliphatic aldehydes. Catalytic loadings as low as 5 mol % give excellent yields in these reactions (up to 99%).
Highly chemoselective direct crossed aliphatic-aromatic acyloin condensations with triazolium-derived carbene catalysts
O'Toole, Sarah E.,Rose, Christopher A.,Gundala, Sivaji,Zeitler, Kirsten,Connon, Stephen J.
supporting information; experimental part, p. 347 - 357 (2011/04/17)
It has been shown for the first time that triazolium precatalysts promote (in the presence of base) highly chemoselective crossed acyloin condensation reactions between aliphatic and ortho-substituted aromatic aldehydes. An o-bromine atom can serve as a temporary directing group to ensure high chemoselectivity (regardless of the nature of the other substituents on the aromatic ring) which then can be conveniently removed. The process is of broad scope and is operationally simple as it does not require the preactivation of any of the coupling partners to ensure selectivtiy. Preliminary data indicate that highly enantioselective variants of the reaction are feasible using chiral precatalysts.
Reduction of 1,2-dicarbonyl compounds mediated by the combination of phosphine and lewis acid
Kikuchi, Satoshi,Hashimoto, Yukihiko
, p. 1267 - 1269 (2007/10/03)
The combination of Ph3P/AlBr3 effectively promoted the reduction of several 1,2-dicarbonyl compounds in the presence of water (1.0 equiv) and the corresponding α-hydroxy carbonyl compounds were obtained in good yields.
Synthesis of 2,5-dihydrofurans via alkylidene carbene insertion reactions
Walker, Louise F.,Bourghida, Ahmed,Connolly, Stephen,Wills, Martin
, p. 965 - 981 (2007/10/03)
The insertion reaction of alkylidene carbenes is demonstrated to be an effective method for the synthesis of 2,5-dihydrofuran ring systems. The best results have been obtained on substrates containing electron-withdrawing substituents, which appear less prone to the competing rearrangement reaction. This insight has led to the development of a new method for the synthesis of the core structure of the squalestatin-zaragozic acid natural products.
