2-Butanone reduction

Hydroxybenzaldehyde has an agreeable aromatic odor, but is not itself a fragrance. It is, however, a useful intermediate in the synthesis of fragrances. The methyl ether of -hydroxybenzaldehyde, ie, -anisaldehyde, is a commercially important fragrance. Anisaldehyde can be made in a simple one-step synthesis from hydroxybenzaldehyde and methyl chloride. Another important fragrance, 4-(p-hydroxyphenyl)butanone, commonly referred to as raspberry ketone, can be prepared from the reaction of -hydroxybenzaldehyde and acetone, followed by reduction (see Flavors and spices). 

Another synthesis of the cortisol side chain from a C17-keto-steroid is shown in Figure 20. Treatment of a C3-protected steroid 3,3-ethanedyidimercapto-androst-4-ene-ll,17-dione [112743-82-5] (144) with a tnhaloacetate, 2inc, and a Lewis acid produces (145). Addition of a phenol and potassium carbonate to (145) in refluxing butanone yields the aryl vinyl ether (146). Concomitant reduction of the C20-ester and the Cll-ketone of (146) with lithium aluminum hydride forms (147). Deprotection of the C3-thioketal, followed by treatment of (148) with y /(7-chlotopetben2oic acid, produces epoxide (149). Hydrolysis of (149) under acidic conditions yields cortisol (29) (181). 

REDUCTIVE ARYLATION OF ELECTRON-DEFICIENT OLEFINS 4- (4-CHLQROPHEHYL1 BirrAN-2-OHE (2-Butanone, 4-(4-ch1oropheny11-1... 

Ketones undergo a reduction when treated with sodium borohydride, NaBH What is the structure of the compound produced by reaction of 2-butanone with NaBH4 if it has an IR absorption at 3400 cm-1 and M+ = 74 in the mass spectrum ... 

MethyloU2-Butanol (2-Methyl-l,3-butanediol or a >Dioxy-/3-methylbutane). CH3.CH(OH).CH(CH2OH).CH3 mw 104.15, viscous oil, bp 200° 98—99° at 9mm. Sol in w, v sol in ale and eth. Can be prepd either by reduction of the corresponding aldehyde, 2-methylbutanol(3)-al-(l) with A1 amalgam (Ref 1), or by electrolytic reduction in 10% sulfuric acid of the corresponding ketone ale. In the latter case, methyl-2-butanone-3-ol-(l), obtained by the condensation of methylethylketone with formaldehyde, can be used. On nitration, it yields an expl dinitrate Refs 1) Beil 1,482,(250) 2)L.P.Kyria-kides, JACS 36, 535(1914)... 

Since the transition state for alcohol oxidation and ketone reduction must be identical, the product distribution (under kinetic control) for reducing 2-butanone and 2-pentanone is also predictable. Thus, one would expect to isolate (R)-2-butanol if the temperature of the reaction was above 26 °C. On the contrary, if the temperature is less than 26 °C, (S)-2-butanol should result in fact, the reduction of... 

The effect of the steric bulk of the hydride reducing agent has been examined in the case of 3-benzyloxy-2-butanone.135 The ratio of chelation-controlled product increased with the steric bulk of the reductant. This is presumably due to amplification of the steric effect of the methyl group in the chelated TS as the reductant becomes more sterically demanding. In these reactions, the degree of chelation control was also enhanced by use of CH2C12 as a cosolvent. 

Scheme 6 Complementary regioselectivities in direct aldol couplings of 2-butanone and corresponding hydrogen-mediated reductive aldol couplings of MVK...

Dining distillation of 2-propanol recovered from the reduction of crotonaldehyde with isopropanol/aluminium isopropoxide, a violent explosion occurred. This was attributed to peroxidised diisopropyl ether (a possible by-product) or to peroxidised crotonaldehyde. An alternative or additional possibility is that the isopropanol may have contained traces of a higher secondary alcohol (e.g. 2-butanol) which would be oxidised during the Meerwein-Ponndorf reduction procedure to 2-butanone. The latter would then effectively sensitise the isopropanol or other peroxidisable species to peroxidation. 

Recently, we adopted the same system for the reduction of 4-phenyl-2-butanone to (S)-4-phenyl-2-butanol using the NADH-dependent horse liver alcohol dehydrogenase (HLADH) and S-ADH from Rhodococcus sp [68] with high enantioselectivity (Fig. 17) [69]. As mediator, we applied the low-molecular... 

Fig. 17. Electroenzymatic reduction of 4-phenyI-2-butanone catalyzed by HLADH with in-situ indirect electrochemical regeneration of NADH using a Cp (2,2 -bipyridyl)aquo rhodium(III) complex as mediator...

Candida parapsilosis was found to be able to convert (k)-1,2-butanediol to (S)-l,2-butanediol through stereospecific oxidation and asymmetric reduction reactions [72]. The oxidation of (k)-1,2-butanediol to l-hydroxy-2-butanone and the reduction of l-hydroxy-2-butanone to (S)-l,2-butanediol were cataly-... 

Several products were also detected in base-degraded D-fructose solution acetoin (3-hydroxy-2-butanone 62), l-hydroxy-2-butanone, and 4-hydroxy-2-butanone. Three benzoquinones were found in the product mixture after sucrose had been heated at 110° in 5% NaOH these were 2-methylbenzoquinone, 2,3,5-trimethylbenzoquinone, and 2,5-dimethyl-benzoquinone (2,5-dimethyl-2,5-cyclohexadiene-l,4-dione 61). Compound 62 is of considerable interest, as 62 and butanedione (biacetyl 60) are involved in the formation of 61 and 2,5-dimethyl-l,4-benzenediol (63) by a reduction-oxidation pathway. This mechanism, shown in Scheme 10, will be discussed in a following section, as it has been proposed from results obtained from cellulose. 

It is synthesized by the reaction of 3,4-dimethoxyphenyl-2-amine and l-(4-methoxyphenyl)-3-butanone with a simultaneous reduction of formed imine, giving the product (11.1.30), the methoxyl-protecting groups of which are cleaved by hydrogen bromide, giving dobutamine (11.1.31) [32,33]. 

Levene and Walti also reduced phytochemically l-hydroxy-3-buta-none to the levorotatory 1,3-butanediol and l-hydroxy-2-heptanone to the dextrorotatory 1,2-heptanediol. It seems that the optically active glycols that are obtained by bioreduction of hydroxy ketones with fermenting yeast are configurationally related. But the 1,3-butanediol that is obtained by the reduction of the l-hydroxy-3-butanone has the opposite configuration from the product of bioreduction of the isomeric d,Z-acetaldol (see p. 81). 

A highly selective method for determination of lipid hydroperoxides is based on the oxidation of ferrocenecarboxylic acid (201) to the corresponding ferrocenium compound (202), as shown in equation 69, followed by amperometric reduction of this complex with a GCE set at —100 mV vs. SCSE, in phosphate buffer at pH 5.5. The method is insensitive to dissolved oxygen and no interference is observed, either from reductors such as ascorbic acid (22) or uric acid (29) nor from other hydroperoxides such as H2O2 and f-BuOOH at the 1 xM concentration level. At this concentration, a slight interference is observed for cumyl hydroperoxide (27) and 2-butanone peroxide (46 4- 47). The LOD... 

---