56955-40-9Relevant academic research and scientific papers
Gold-catalyzed regioselective hydration of propargyl acetates assisted by a neighboring carbonyl group: Access to α-acyloxy methyl ketones and synthesis of (±)-actinopolymorphol B
Ghosh, Nayan,Nayak, Sanatan,Sahoo, Akhila K.
, p. 500 - 511 (2011/04/17)
A general atom-economical approach for the synthesis of α-acyloxy methyl ketone is demonstrated through regioselective hydration of a wide range of propargyl acetates. Readily available catalyst comprising of 1% Ph 3PAuCl and 1% AgSbF6 in dioxane-H2O efficiently hydrolyzes the terminal alkynes of the propargyl acetate in the absence of acid promoters at ambient temperature within a short time. Effective regioselective hydration is facilitated by the neighboring carbonyl group as demonstrated through 18O-labeling study. Compatibility of functional moieties and tolerance to various acid-labile protecting groups are observed. The catalytic condition is also suitable to perform hydration of TMS-substituted propargyl acetates, even though it requires prolonged reaction time for completion. Stereointegrity of the propargylic acetate is preserved during the hydration. The robustness of the system is successfully demonstrated through gram scale preparation of the product in nearly quantitative yield. The common α-acyloxy methyl ketone is transformed to 1,2-diol and 1,2-amino alcohol derivatives. Synthesis of actinopolymorphol B is achieved for the first time involving hydration of the propargyl acetate as the key step.
Conversion of propargylic alcohols to β-oxo esters catalyzed by novel ruthenium-phosphoramidite complexes
Costin, Stephen,Rath, Nigam P.,Bauer, Eike B.
supporting information; experimental part, p. 2414 - 2424 (2009/11/30)
A series of half-sandwich phosphoramidite complexes of ruthenium were synthesized and employed as catalysts in the atom-economical formation of β-oxo esters from carboxylic acids and propargylic alcohols. Reaction of the phosphoramidites (R)-BINOL-PNR2 (R=Me, 1a; i-Pr, 1b; benzyl, 1c) and (rac)-6,6′-dibromo-BINOL-PNMe2 (1d) with the dimeric p-cymene-ruthenium dichloride complex, [RuCl2(p-cymene)]2, gave the complexes [RuCl2(p-cymene)(L)] (L=1a, 7a; 1b, 7b; 1c, 7c; 1d, 7d) in 96-66% yield. Accordingly, reaction of (R)-BINOL(8H)-PNMe2 (2a) and (R)-BINOL(8H)-PN-(benzyl)2 (2b) with [RuCl2(p-cymene)] 2 afforded the complexes [RuCl2(p-cymene)(L)] (L=2a, 8a; 2b, 8b) in 82% and 86% yield. In a similar reaction, treatment of (R)-BIPHEN-PNMe2 (9) with [RuCl2(p-cymene)] 2 gave the complex [RuCl2(p-cymene)(9)] (11) in 60% yield. Finally, phosphoramidite 1b reacted with [RuCl2(C6Me 6)]2 to give [RuCl2(C6Me 6)(1b)] (12) in 78% yield. All novel complexes are catalytically active in the formation of β-oxo esters from propargylic alcohols and carboxylic acids. Standard conditions involve cyclohexane solvent, propargylic alcohol (1.0 equiv.), carboxylic acid (1.0 equiv.), ruthenium catalyst (1.5 mol%), and 90°C for 5-18 h. Isolated yields of the β-oxo esters range from 87 to 16% and show broad substrate generality. The reaction proceeds without racemization if a chiral propargylic alcohol is employed. The method is practical as no additives are required and the exclusion of oxygen and moisture is not needed. Complex 7c turned out to be the most effective catalyst (5 h reaction time), showing that the ligand structure has a profound impact on the catalytic performance. The crystal structure of 7a was determined, confirming an octahedral coordination geometry about the ruthenium center.
Mg-promoted carbon-acylation of aromatic aldehydes and ketones
Nishiguchi, Ikuzo,Sakai, Masahiro,Maekawa, Hirofumi,Ohno, Toshinobu,Yamamoto, Yoshimasa,Ishino, Yoshio
, p. 635 - 637 (2007/10/03)
Reductive cross-coupling of aromatic aldehydes and ketones with aliphatic acid chlorides promoted by Mg turnings in DMF at room temperature brought about efficient C-acylation to afford the corresponding α-acyloxy-α-aryl ketones in good yields. Treatment
