65248-91-1Relevant academic research and scientific papers
A heterogeneous gold(I)-catalyzed regioselective hydration of propargyl acetates toward α-acyloxy methyl ketones
Cai, Mingzhong,Du, Yingying,Yao, Fang,Zhang, Rongli
, (2020/02/04)
A heterogeneous gold(I)-catalyzed regioselective hydration of propargyl acetates has been developed that proceeds smoothly in 1,4-dioxane at room temperature in the presence of 1 mol% diphenylphosphine-modified MCM-41-anchored gold(I) complex [Ph2P-MCM-41-AuSbF6] as catalyst and provides an efficient and practical approach for the synthesis of a variety of α-acyloxy methyl ketones with high atom economy, good to excellent yield, and high functional group tolerance. This new immobilized gold(I) catalyst can readily be obtained by a simple preparative procedure from commercially available reagents, and recovered via a filtration process and reused at least seven times without apparent loss of activity.
"Silver effect" in gold(I) catalysis: An overlooked important factor
Wang, Dawei,Cai, Rong,Sharma, Sripadh,Jirak, James,Thummanapelli, Sravan K.,Akhmedov, Novruz G.,Zhang, Hui,Liu, Xingbo,Petersen, Jeffrey L.,Shi, Xiaodong
supporting information; experimental part, p. 9012 - 9019 (2012/07/02)
Clear experimental evidence from X-ray photoelectron spectroscopy and 31P NMR spectroscopy has been obtained for the first time to confirm that the combination of Ag+ cation with [L-Au]+ results in the formation of different complexes in solution. Re-evaluation of literature-reported gold-catalyzed reactions revealed a significant difference in the reactivities with and without silver. In extreme cases (more than "rare"), the conventional [L-Au]+ catalysts could not promote the reaction without the presence of silver. This investigation has therefore revealed a long-overlooked "silver effect" in gold catalysis and should lead to revision of the actual mechanism.
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.
supporting information; experimental part, 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.
A new route to protected acyloins and their enzymatic resolution with lipases
Scheid, Guenther,Kuit, Wouter,Ruijter, Eelco,Orru, Romano V. A.,Henke, Erik,Bornscheuer, Uwe,Wessjohann, Ludger A.
, p. 1063 - 1074 (2007/10/03)
A series of 16 different 3-acyloxy methyl ketones, the acyloin acetates and butyrates (±)-5, was synthesised by a straight-forward new method through alkylation of tert-butyl 2-acyloxyacetoacetates 3, followed by chemoselective dealkoxy-carbonylation of the tert-butyloxycarbonyl group in the presence of other ester groups. Subsequent hydrolysis of (±)-5 can be achieved with base to give racemic acyloins 6, or with lipase catalysis to afford the corresponding non-racemic acyloins (S)-6. The remaining (R)-acyloin esters 5 can be racemised and resubjected to the procedure, or hydrolysed chemically. The kinetic resolution with two of the six tested enzymes, CAL-B and BCL (PS) lipase, proceeded selectively [enantiomeric ratio (E) values between 50 and > 200] and most of the acyloins (S)-6 were obtained in very high enantiomeric excesses (up to > 99% ee). Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
