- Stereoselective synthesis of alicyclic ketones: A hydrogen borrowing approach
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A highly diastereoselective annulation strategy for the synthesis of alicyclic ketones from diols and pentamethylacetophenone is described. This process is mediated by a commercially available iridium(III) catalyst, and provides efficient access to a wide range of cyclopentane and cyclohexane products with high levels of stereoselectivity. The origins of diastereoselectivity in the annulation reaction have been explored by a series of control experiments, which provides an explanation for how each stereocentre around the newly forged ring is controlled.
- Armstrong, Roly J.,Akhtar, Wasim M.,Frost, James R.,Christensen, Kirsten E.,Stevenson, Neil G.,Donohoe, Timothy J.
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supporting information
(2019/11/13)
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- Stereoselective Synthesis of Cyclohexanes via an Iridium Catalyzed (5 + 1) Annulation Strategy
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An iridium catalyzed method for the synthesis of functionalized cyclohexanes from methyl ketones and 1,5-diols is described. This process operates by two sequential hydrogen borrowing reactions, providing direct access to multisubstituted cyclic products with high levels of stereocontrol. This methodology represents a novel (5 + 1) strategy for the stereoselective construction of the cyclohexane core.
- Akhtar, Wasim M.,Armstrong, Roly J.,Frost, James R.,Stevenson, Neil G.,Donohoe, Timothy J.
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supporting information
p. 11916 - 11920
(2018/09/27)
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- Mild and practical acylation of alcohols with esters or acetic anhydride under distannoxane catalysis
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Distannoxane catalysts effect acylation of alcohols by action of esters and acetic anhydride. In particular, use of enol esters provides an extremely useful method. Primary alcohols are acylated in preference to secondary ones as well as phenol. Both acid- and base-sensitive functional groups remain intact. Especially unique is the discrimination of thio function which is completely tolerant under the present reaction conditions. This method is highly practical since operation is quite simple. Esters and solvents can be used without purification and no inert atmosphere is necessary. The products can be isolated simply by column chromatography or distillation without aqueous workup.
- Orita, Akihiro,Sakamoto, Katsumasa,Hamada, Yuji,Mitsutome, Akihiro,Otera, Junzo
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p. 2899 - 2910
(2007/10/03)
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- Organotin-Mediated Monoacylation of Diols with Reversed Chemoselectivity: A Convenient Synthetic Method
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The organotin-mediated monoesterification of unsymmetrical diols with reversed chemoselectivity has been explored to ascertain scope and limits of the method and to provide an easy and convenient synthetic procedure.The reaction has been performed on a set of substituted diols with some acylating agents usually employed as protecting groups.Two different procedures have been devised to obtain either the desired diol monoesters directly or the corresponding trialkylsilyl ethers as protected derivatives.The latter provides a convenient approach to the preparation of easily interconvertible diol monoesters.Also, the reaction has been optimized as a one-pot procedure, avoiding the isolation and purification of the stannylated intermediates.The reversed monoesterification method has been successfully applied to 1,2-, 1,3-, and 1,4-diols of primary-secondary, primary-tertiary, and secondary-tertiary types and to ether functions containing 1,2-diols.Within its limits, the described method represents the first direct one-pot monoesterification of diols at the most substituted site, allowing some remarkable achievements as (a) an almost regiospecific reversed monobenzoylation of some 1,2-diols, (b) the selective acylation of the tertiary hydroxyl of a primary-tertiary diol, and (c) a highly selective preparation of secondary pivalate of primary-secondary diols.
- Reginato, Gianna,Ricci, Alfredo,Roelens, Stefano,Scapecchi, Serena
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p. 5132 - 5139
(2007/10/02)
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- 3-ACYL-2-OXAZOLONE-ZIRCONIUM COMPLEXES AS EXCELLENT REAGENTS FOR HIGHLY REGIOSELECTIVE ACYLATION OF POLYALCOHOLS
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In combination with 3-acyl-2-oxazolones, zirconium complexes such as zirconium acetylacetonate and zirconocene chloride hydride-Mg serve well as effective catalysts for regioselective acylation of polyalcohols including 1,2-diols to permit higly preferential protection of primary hydroxyl groups.
- Kunieda, Takehisa,Mori, Takashi,Higuchi, Tsunehiko,Hirobe, Masaaki
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p. 1977 - 1980
(2007/10/02)
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