Alcohols, synthesis carbonyl compounds

The oxidation of alcohols to carbonyl compounds is one of the most relevant transformations in organic synthesis, due to the large diversity of products that can be obtained from aldehyde and ketone precursors. 

The oxidation of alcohols to carbonyl compounds with the stable nitroxyl radical TEMPO (86) as catalyst is a well-known preparative method [134, 135]. Hypochlorite or peracetic acid is usually used as the final oxidizing agent and ca. 1 mol% of catalyst 86 is used. In 1996 Rychnovsky et al. reported the synthesis of the chiral, binaphthyl-derived TEMPO analog 87 [136], Results obtained by use of 0.5-1 mol% of catalyst 87 [136] are listed in Table 10.12. In these oxidation reactions 0.6-0.7 equiv. sodium hypochlorite were used as the final oxidizing agent (plus... 

The enhanced reactivity of oxiranes due to geometric strain is manifested in their acid- and base-catalyzed reactions, in their rearrangements in the presence of metals and metal compounds, and in their thermal and photocatalytic transformations. These reactions permit the development of new and varied methods of synthesis and the preparation of derivatives that in many cases are difficult to obtain by other routes. The main products of the isomerization reaction are unsaturated alcohols and carbonyl compounds. Great progress has been made in this area of organic chemistry during the past 20 years (The reader is referred to some relevant... 

Hinzen, B., Lenz, R., Ley, S. V. Polymer supported perruthenate (PSP). Clean oxidation of primary alcohols to carbonyl compounds using oxygen as cooxidant. Synthesis 1998, 977-979. 

Huang, S. L., Omura, K., Swern, D. Further studies on the oxidation of alcohols to carbonyl compounds by dimethyl sulfoxide/trifluoroacetic anhydride. Synthesis 1978, 297-299. 

Oxidation with dimethyl sulfoxide (DMSO), which is known as Swern-Moffatt oxidation, is one of the most versatile and reliable methods for the oxidation of alcohols to carbonyl compounds and is widely utilized in laboratory organic synthesis. Avoidance of heavy metals such as Mn and... 

Oxidation of alcohols or carbonyl compounds (general method). Synthesis of 2-cyclooctenone.1 To a solution of cyclooctanol 1 (1 mmol) in fluorobenzene DMSO (2 1, 0.1 M) was added 2.2 equiv of IBX and the solution was heated to 55-65 °C (or to 85 °C for synthesis of 3). The reaction was monitored by TLC. Dilution with Et20 and usual work up followed by flash chromatography afforded 2-cyclooctenone 2 in 77% yield. 

The Heck reaction has been used to synthesize several alkenylthiophenes. Under Pd catalysis, thienyl halides react with suitable alkenes to form the products (599). In the case of allylic alcohols, the carbonyl compound (600) is the main product (Scheme 136). The method has been extended to the synthesis of styrylthiophenes <88TL4409>. The product appears to have the -configuration about the double bond, whereas the expected simple cis-addition of the thienylpalladium species followed... 

Both IBX (799) and DMP (800) are now extensively employed in organic synthesis as mild and highly selective reagents for the oxidation of alcohols to carbonyl compounds, as well as for various other synthetically useful oxidative transformations [1102, 1104-1106], For optimized experimental procedures for the preparation of IBX (Section 2.2.3.1) and DMP (Section 2.2.3.2), see Chapter 2. 

Applications of IBX in organic synthesis have been summarized in several comprehensive reviews [1105, 1106], IBX is a particularly useful oxidant for the selective oxidation of alcohols to carbonyl compounds, even in complex molecules in the presence of other functional groups. Primary alcohols are oxidized by IBX in DMSO to the corresponding aldehydes at room temperature without overoxidation to the acids. The chiral primary alcohols are oxidized without epimerization and various functional groups like thioethers, amines, carboxylic acids, esters, carboxamides and both conjugated and isolated double bonds are compatible with IBX [1132,1133]. Several representative examples of alcohol oxidations using IBX in DMSO are shown below in Schemes 3.330-3.335. 

Microflow systems serve as effective environments to perform various oxidation reactions using chemical reagents. The oxidation using dimethyl sulfoxide (DMSO), which is known as Moffatt-Swern type oxidation, is one of the most versatile and reliable methods for the oxidation of alcohols into carbonyl compounds in laboratory synthesis [1, 2]. However, it is well known that activation of DMSO leads to an inevitable side-reaction, Pummerer rearrangement, at temperatures above — 30°C (Scheme 7.1). Therefore, the reaction is usually carried out at low temperatures (—50 °C or below), where such a side-reaction is very slow [3, 4]. However, the requirement for such low temperatures causes severe limitations in the industrial use of this highly useful reaction. The use of microflow systems solves the problem. For example, the oxidation of cyclohexanol can be accomplished using a microflow... 

Mild oxidation of alcohols to carbonyl compounds via alkoxysulfonium ylides is a very important transformation in organic synthesis and several reviews cover many of the practical and mechanistic aspects of the Moffatt, Swern, and related oxidations [1316-1320]. 

Mancuso, A. J. Swern, D. Activated Dimethyl Sulfoxide Useful Reagents for Synthesis Synthesis 1981,165-185. Mancuso, A. J. Brownfain, D. S. Swern, D. Structure of the Dimethyl Sulfoxide-Oxalyl Chloride Reaction Product. Oxidation of Heteroaromatic and Diverse Alcohols to Carbonyl Compounds /. Org. Chem. 1979, 44, 4148-4150. Mancuso, A. J. Huang, S-L. Swern, E. Oxidation of Long-Chain and Related Alcohols to Carbonyls by Dimethyl Sulfoxide Activated by Oxalyl Chloride J. Org. Chem. 1978, 45, 2480-2482. Omura, K. Swern, D. Oxidation of Alcohols by Activated Dimethyl Sulfoxide. A Preparative Steric and Mechanistic Study Tetrahedron 1978, 54, 1651-1660. 

SYNTHESIS OF ALCOHOLS OXIDATION-REDUCTION RELATION BETWEEN ALCOHOLS AND CARBONYL COMPOUNDS... 

Alcohols provide the most common starting materials for the synthesis of carbonyl compounds. Because alcohols can be prepared by a variety of synthetic methods, they are very important synthetic intermediates. Oxidation of alcohols yields carbonyl compounds. Primary alcohols yield aldehydes secondary alcohols yield ketones. However, we recall that the oxidation of primary alcohols is comphcated because aldehydes are easily oxidized to carboxyhc acids. Thus, PCC, which does not oxidize aldehydes, is the reagent of choice for the oxidation of primary alcohols. Secondary alcohols can be oxidized by either PCC or the Jones reagent (Section 16.4). 

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