Summary Alcohol Syntheses

Hydroxylation forms vicinal dials (glycols) (Sections 8-13 and 8-14) a. Syn hydroxylation, using KMnOJNaOH or using OsO/H O  

Second-order substitution primary (and some secondary) halides 

FROM CARBONYL COMPOUNDS NUCLEOPHILIC ADDITION TO THE CARBONYL GROUP 

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Mechanism 10-2 Hydride Reduction of a Carbonyl Group 454 Summary Reactions of LiAIH4 and NaBH4 455 Summary Alcohol Syntheses by Nucleophilic Additions to Carbonyl Groups 457 10-12 Thiols (Mercaptans) 458 EssentialTerms 461 Study Problems 462... 

Structure and Classification of Alcohols 425 10-3 Nomenclature of Alcohols and Phenols 427 10-4 Physical Properties of Alcohols 430 10-5 Commercially Important Alcohols 433 10-6 Acidity of Alcohols and Phenols 435 10-7 Synthesis of Alcohols Introduction and Review 438 Summary Previous Alcohol Syntheses 438 10-8 Organometallic Reagents for Alcohol Synthesis 440 10-9 Addition of Organometallic Reagents to Carbonyl Compounds 443... 

Carbon monoxide may be hydrogenated to produce either alcohols or hydrocarbons, depending on the catalysts used and the reaction conditions. Temperatures ranging from 100-400°C and pressures as high as 1,000 atm have been studied. Different catalysts yield radically different types of products. Important processes for uch reactions consist of the methanol synthesis, the higher-alcohol synthesis (or the variation termed the iso synthesis), the Fischer-Tropsch reaction (or the version called hydrocarbon synthesis), and the methanation reaction. These syntheses were discovered in the period 1920-1925, at which time the methanol and higher-alcohol syntheses developed rapidly. A brief summary of processes and conditions used for the hydrogenation of carbon monoxide is presented in Table 10-17. 

In summary, the research effort aimed towards active, chemoselective hydrogenations of certain C=0 and C=N bonds have delivered several catalysts that approach the level of activity required for use in the synthesis of alcohols and amines. However, other classes of substrate require considerable additional investigations to be conducted before homogeneous catalysts may be considered for this purpose. 

With both building blocks 103 and 109 in hand, the total synthesis of lb was completed as shown in Scheme 17. Coupling of acid 103 and alcohol 109 under Yamaguchi conditions to give ester 110 and subsequent desilylation followed by chemoselective oxidation provided hydroxy acid 111. Lactonization of the 2-thiopyridyl ester derived from 111 in the presence of cupric bromide produced the macrodiolide 112 in 62% yield, which was finally converted to pamamycin-607 (lb) via one-pot azide reduction/double reductive AT-methylation. In summary, 36 steps were necessary to accomplish the synthesis of lb from alcohols 88 and 104, sulfone 91, ketone 93, and iodide rac-97. 

In summary, the organically functionalized Ti-substituted MCM-41 materials have been successfully synthesized by one-step synthesis method with a varied Ti-incorporation of the Si/Ti ratio from 50 to 600. The hydrothermal treatment resulted in the increase of Ti-incorporation. The epoxidation selectivity was improved by organic functionalization than alcohol oxidation probably due to the increased hydrophobicity nearby the Ti-active sites. 

In summary, the polymer-bound oxoammonium reagent was highly efficient in polymer-supported oxidations of various alcohols and was capable of cleanly converting chemically diverse compound collections. No overoxidation to carboxylic acids was observed. It is obvious that this reagent shall be of great value in polymer-supported transformations in solution, in automated parallel synthesis operations, and in flow-through reactors in up-scaled production processes. 

Key Mechanism 11-6 The Williamson Ether Synthesis 500 Problem-Solving Strategy Multistep Synthesis 502 Summary Reactions of Alcohols 505 Essential Terms 508 Study Problems 509... 

Synthesis of Ethers by Alkoxymercuration-Demercuration 636 14-7 Industrial Synthesis Bimolecular Condensation of Alcohols 637 Summary Syntheses of Ethers (Review) 638 14-8 Cleavage of Ethers by HBr and HI 638... 

In summary, we have developed a recyclable heterogeneous catalyst for the bleach oxidation of alcohols and polyols. In contrast to previously reported systems, neither a chlorinated hydrocarbon solvent nor a bromide cocatalyst is necessary to achieve good activity. Besides bleach-oxidation, PIPO is also effective in the CuCl/nitroxyl catalysed aerobic oxidation of benzyl alcohol. A further advantage of our system is that PIPO is readily prepared from inexpensive and commercially available raw materials. We believe that it will find wide application in organic synthesis. 

In summary, these studies demonstrated that in CTX the impaired synthesis of bile acids is due to a defect in the biosynthetic pathway involving the oxidation of the cholesterol side-chain. As a consequence of the inefficient side-chain oxidation, increased 23, 24 and 25-hydroxylation of bile acid precursors occurs with the consequent marked increase in bile alcohol glucuronides secretions in bile, urine, plasma and feces (free bile alcohols). These compounds were isolated, synthesized and fully characterized by various spectroscopic methods. In addition, their absolute stereochemistiy determined by Lanthanide-Induced Circular Dichroism (CD) and Sharpless Asymmetric Dihydroxylation studies. Further studies demonstrated that (CTX) patients transform cholesterol into bile acids predominantly via the 25-hydroxylation pathway. This pathway involves the 25-hydroxylation of 5P-cholestane-3a,7a, 12a-triol to give 5P-cholestane-5P-cholestane-3a,7a,12a,25- tetrol followed by stereospecific 24S-hydroxylation to yield 5P-cholestane-3a,7a,12a,24S,25-pentol which in turn was converted to cholic acid. 

Preparation. Johnson and co-workers give a procedure for the preparation of a solution of potassium r-butoxide in r-butanol under nitrogen. Skattebpl and Solomon describe preparation of the solution by the same method and for evaporating it to solvent-free solid (for a summary, see Methyllithium, allene synthesis). The reagent can be prepared also from potassium purified with /-amyl alcohol see Potassium, Pearson s procedure). 

In summary, depending on reaction condition, we have described a novel and versatile direct synthesis of alkyl N-cyano-N-substituted carbamates or N,N-disubstituted cyanamides. The required intermediates can be prepared in good yields from cyanamide, carbon disulfidtj potassium hydroxide, alkyl or benzyl alcohols and alkyl or benzyl halides which are readily available and inexpensive. 

Asymmetric Induction at the Allylic Alcohol Centre AE is anti-Selective No Asymmetric Induction from Remote Allylic Alcohol Centre Reagent Control Asymmetric Synthesis of Diltiazem Summary of Sharpless Epoxidation... 

Treatment of the ketone with two equivalents of bromine, followed by hydrazone formation, finally effected closure of the ether bridge with concomitant elimination to hydrazone 58.45c Hydrolysis to the enone, followed by reduction, removed both the aryl bromide and introduced the alcohol stereoselectively to give natural codeine 2,12>45 which was demethylated under established conditions46 to yield morphine l.12-45 A summary of these studies can be divided into synthesis of 50,41 Cu-chromite reductive cyclization,45d isomerization of Ci4,45c reduction to codeine,456 and a full paper sumary.45a... 

A brief summary of the information available till around 1990 [211] shows the use of three reverse microemulsion systems for the synthesis of (amorphous) silica particles AOT /isooctane /water, AOT /benzyl alcohol/ decane /water and NP-5 /cyclohexane/ water. Note that the dispersed water phase had a dissolved base (NH4OH) or acid (HCl) as catalyst in it. Tetraethyl orthosilicate (TEOS) was added to the reverse microemulsions, leading to hydrolysis-condensation reaction and formation of silica particles. The size of the particles depended on the experimental conditions, but could go down to about 15 nm. 

Scheme 11.3 Synthesis of zeolite supported chiral catalyst. The chiral catalyst promotes various aliphatic and aromatic ketone reductions to their reduced chiral secondary alcohols. A summary of the examples have been summarized in Table 11.4.

For the preparation of double salts and alkoxides, the most popular method involves dissolving the two alkoxides in a mutual solvent, mixing the solutions, and refluxing at elevated temperatures (eg, refluxing an aluminium sec-butoxide and magnesium methoxide in alcohol at 600 K). One can also prepare a double alkoxide by refluxing the oxide of the first element with the alkoxide of the second element in alcohol. Bradley and co-workers (16) provided an excellent summary of available double alkoxides and techniques used in their synthesis. 

In summary, a three-way coupling is performed using alcohols 985, carbon dioxide, and halides 988, leading to the exclusive synthesis of mixed alkyl carbonates 989. 

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