SmI2-Mediated 3-exo-trig cyclisation of δ-oxo-α,β-unsaturated esters to cyclopropanols and derivatives
摘要:
In the presence of samarium diiodide and a proton source, delta-oxo-gamma,gamma-disubstituted-alpha,beta-unsaturated esters of general formula R-CO-C(R',R')-CH=CH-CO2Bn readily cyclise to trans-cyclopropanol products and/or lactones derived from the cis isomers. For R=aryl, good stereoselectivities (ca 90%) in favor of the alcohols are generally obtained while a mixture of alcohols and lactones is obtained with R=alkyl or H. For R=cyclopropyl, the lactone is exclusively obtained in more than 90% yield. A mechanistic rationalisation of these variations of diastereoselectivity is proposed. (C) 2004 Elsevier Ltd. All rights reserved.
Polystyrene-Supported (Catecholato)oxorhenium Complexes: Catalysts for Alcohol Oxidation with DMSO and for Deoxygenation of Epoxides to Alkenes with Triphenylphosphine
Re-catalyzed alcoholoxidation is inexpensive and safer for transport and storage than commonly used peroxide reagents. The oxidation procedure was best suited for aliphatic alcohols, and the mild conditions were compatible with unprotected functional groups, such as those of alkenes, phenols, nitro compounds, and ketones (see Tables 1 and 2). Selective oxidation of secondary alcohols in the presence of
The reaction of (chloromethylene)dimethylammonium chloride (generated in situ from oxalyl chloride and DMF) with α-substituted ketones in CH2Cl2, followed by workup with aqueous NaHCO3, gave β-keto aldehydes containing an α-quaternary centre (8-88% yield).
9-azanoradamantane N—oxyl compound and method for producing same, and organic oxidation catalyst and method for oxidizing alcohols using 9-azanoradamantane N—oxyl compound
申请人:TOHOKU UNIVERSITY
公开号:US09114390B2
公开(公告)日:2015-08-25
An organocatalyst for oxidizing alcohols in which a primary alcohol is selectively oxidized in a polyol substrate having a plurality of alcohols under environmentally-friendly conditions. The organic oxidation catalyst has an oxygen atom bonded to a nitrogen atom of an azanoradamantane skeleton and at least one alkyl group at positions 1 and 5. The oxidation catalyst has higher activity than TEMPO, which is an existing oxidation catalyst, in the selective oxidation reaction of primary alcohols, and better selectivity than AZADO and 1-Me-AZADO. This DMN-AZADO can be applied to the selective oxidation reaction of primary alcohols that contributes to shortening the synthesizing process for pharmaceuticals, pharmaceutical raw materials, agricultural chemicals, cosmetics, organic materials, and other such high value-added organic compounds.
Development of a stable nitroxyl radical class of catalysts, 2-azaadamantane N-oxyl (AZADO) and 1-Me-AZADO, for highly efficient oxidation of alcohols is described. AZADO and 1-Me-AZADO exhibit superior catalytic proficiency to TEMPO, converting various sterically hindered alcohols to the corresponding carbonyl compounds in excellent yields.
A new alternative system for the chemoselective oxidation of secondary hydroxyl group to ketone with IBX/n-Bu4NBr in CH2Cl2–H2O has been developed. Under the reaction conditions, the secondary hydroxyl group was highly chemoselectively oxidized to the corresponding ketone, in moderate to good yields at rt, in the presence of primary hydroxyl group within the same molecule.