Alcohol From ketone

Another possibility for asymmetric reduction is the use of chiral complex hydrides derived from LiAlH. and chiral alcohols, e.g. N-methylephedrine (I. Jacquet, 1974), or 1,4-bis(dimethylamino)butanediol (D. Seebach, 1974). But stereoselectivities are mostly below 50%. At the present time attempts to form chiral alcohols from ketones are less successful than the asymmetric reduction of C = C double bonds via hydroboration or hydrogenation with Wilkinson type catalysts (G. Zweifel, 1963 H.B. Kagan, 1978 see p. 102f.). 

E. Tertiary alcohols from ketones, esters, and lactones... 

Preparation of enantiomerically pare secondary amines by catalytic asymmetric hydrogenation or hydrosilylation of imines is as important as the preparation of alcohols from ketones. However, asymmetric hydrogenation of prochiral ON double bonds has received relatively less attention despite the obvious preparative potential of this process.98... 

Asymmetric catalytic reduction reactions represent one of the most efficient and convenient methods to prepare a wide range of enantiomerically pure compounds (i.e. a-amino acids can be prepared from a-enamides, alcohols from ketones and amines from oximes or imines). The chirality transfer can be accomplished by different types of chiral catalysts metallic catalysts are very efficient for the hydrogenation of olefins, some ketones and oximes, while nonmetallic catalysts provide a complementary method for ketone and oxime hydrogenation. 

IR interpretation can be as simple or as complicated as you d like to make it. You ve already seen how to distinguish alcohols from ketones by correlation of the positions and intensities of various peaks in your spectrum with positions listed in IR tables or correlation tables. This is a fairly standard procedure and is probably covered very well in your textbook. The things that are not in your text are... 

Enantioselective organic synthesis using modified skeletal catalysts has wide application in areas such as pharmaceutical production for example, synthesis of chiral alcohols from ketones [90], which is described in detail elsewhere in this book. 

Another method, in particular for the preparation of alcohols from ketones involves the transfer of hydrogen from a hydrogen donor. The classic example is the commercially applied Meerwein-Ponndorff-Verley reaction, which uses stoichiometric amounts of Al(O Pr)3 to produce acetone and the alkoxides of the alcohols desired [31], The catalytic version of this reaction, employing... 

Microbial reduction has been recognized for decades as a laboratory method of preparing alcohols from ketones with exquisite enantioselectivity. The baker s yeast system represents one of the better known examples of biocatalysis, taught on many undergraduate chemistry courses. Numerous other microorganisms also produce the ADH enzymes (KREDs) responsible for asymmetric ketone reduction, and so suitable biocatalysts have traditionally been identified by extensive microbial screening. Homann et have... 

Thus, if trimethylsilyl anion were used as the nucleophile, then requisite diastereomer 30 could become available. Of the various counterions, Li+, Na+, and K+ have been examined by others. None of these species were suitable for direct 1,2-addition to carbonyl compounds. For example, trimethylsilyl lithium (Me3SiLi) adds nicely 1,4- to enones by a one-electron-transfer process, but does not provide a-silyl alcohols from ketones or aldehydes. In contrast tris(trimethylsilyl)alumi-... 

The metal lias to a great extent replaced zinc, which was used in 1849 by Frankland in the preparation of paraffin hydrocarbons and the zinc alkyls, and subsequently by Wagner for preparing secondary alcohol from aldehydes, by Saytzeff in preparing tertiary alcohols from ketones, and by Butlerow iu the preparation of both ketones and tertiary alcohols from acid chlorides. 

Aldehydes and ketones when reduced yield alcohols with a hydride ion that is provided by reducing reagents like sodium borohydride or lithiumborohydride. Primary alcohols are obtained from aldehydes and secondary alcohols from ketones. 

Related Methods Alcohols from Ketones (Section 42)... 

Several methods promoted by a stoichiometric amount of chiral Lewis acid 38 [51] or chiral Lewis bases 39 [52, 53] and 40 [53] have been developed for enantioselective indium-mediated allylation of aldehydes and ketones by the Loh group. A combination of a chiral trimethylsilyl ether derived from norpseu-doephedrine and allyltrimethylsilane is also convenient for synthesis of enan-tiopure homoallylic alcohols from ketones [54,55]. Asymmetric carbonyl addition by chirally modified allylic metal reagents, to which chiral auxiliaries are covalently bonded, is also an efficient method to obtain enantiomerically enriched homoallylic alcohols and various excellent chiral allylating agents have been developed for example, (lS,2S)-pseudoephedrine- and (lF,2F)-cyclohex-ane-1,2-diamine-derived allylsilanes [56], polymer-supported chiral allylboron reagents [57], and a bisoxazoline-modified chiral allylzinc reagent [58]. An al-lyl transfer reaction from a chiral crotyl donor opened a way to highly enantioselective and a-selective crotylation of aldehydes [59-62]. Enzymatic routes to enantioselective allylation of carbonyl compounds have still not appeared. 

This method is widely used for the preparation of secondary alcohols from ketones. The reduction of aldehydes is important only when these substances are readily available, e.g., heptanal and furfural. 

Several approaches are available for the synthesis of enantiomerically enriched alcohols from ketones.The three main strategies to obtain enantiomerically enriched (nonracemic) material are listed below. 

Arens-van Dorp synthesis. The preparation of alkoxyethynyl alcohols from ketones and ethox-yacetylene. In the Isler modification, (i-ch loro vinyl ether is reacted with lithium amide to give lithium ethoxyacetylene which is then condensed with the ketone. This avoids the tedious preparation of ethoxyacetylene. 

Favorskii-Babayan synthesis. Synthesis of acetylenic alcohols from ketones and terminal acetylenes in the presence of anhydrous alkali. 

One of the most valuable usage for the McReynolds system is to identify stationary phases. For example, SE-30 and DC-200 or OV-101 are very similar stationary phases (with different names but practically similar retention patterns). This system also allow for a rapid selection of phases with different retention properties, to separate compounds that have different functional groups, such as alcohol from ketones, aromatic fi-om aHphatics, or saturates from unsatvaates. It shoxdd be noted that the McReynolds system is not only apphed to packed columns, but also to the selection of capillary column stationary phases. 

Potassium alkoxide Sec. alcohols from ketones a. 5, 214 KOR CO —CHOH... 

---