Reduction acetals

Acetate, (reduction with) ascorbic acid + KI, citrate, V,V-dihydroxyethylglycine, EDTA, F , formate, NaOH + H2O2, oxidation to CrOJ , NagP30io, sulfosalicylate, tartrate, triethylam-ine, tiron... 

Pregnenolone acetate reduction with lithium aluminum tn t butoxy hydride, 46, 58... 

Fig. 3.8. Acetate reduction in batch cultivation of R. rubrum at an agitation speed of 200 rpm and light intensity of 1000 lux.

The cobaltous acetate reduction of tert-butyl hydroperoxide in acetic acid yields mainly ter/-butanol and oxygen the metal ion stays in the +2 oxidation state because of the reactivity of Co(III) towards hydroperoxides (p. 378) °. The rate law is... 

Alkyl halides and triflates, alkane reduction, 27-32 alkyl halides, 28-31 a-halocarbonyl compounds, 31 vinyl and aryl halides and triflates, 32 Alkynes, alkane reduction, 45-46 Allyl acetates, reduction of, 51 Allyl alcohols ... 

Moreover, alcohol functionalities have been introduced into the polynor-bornene (PNB) backbone by copolymerization of norbornene with a few percent of 5-acetate norbornene and subsequent acetate reduction. After transformation of the pendant hydroxyl functions into diethyl aluminum alkoxides, sCL has been ring opening polymerized (Scheme 31). Owing to the controlled/ liv-ing character of both polymerization processes the isolated poly(NB- -CL) graft copolymers were characterized by well-defined composition, controlled molecular weight and branching density, and narrow MWD (PDI=1.2-1.4) [92]. 

Alcohols are oxidized to aldehydes by the liver enzyme alcohol dehydrogenase, and aldehydes to carboxylic acids by aldehyde dehydrogenase. In mammals, monooxygenases can be induced by plant secondary metabolites such as a-pinene, caffeine, or isobornyl acetate. Reduction is less common and plays a role with ketones that cannot be further oxidized. Hydrolysis, the degradation of a compound with addition of water, is also less common than oxidation. 

Divalent chromium salts show very strong reducing properties. They are prepared by reduction of chromium(III) compounds with zinc [187] or a zinc-copper couple and form dark blue solutions extremely sensitive to air. Most frequently used salts are chromous chloride [7SS], chromous sulfate [189], and less often chromous acetate. Reductions of organic compounds are carried out in homogeneous solutions in aqueous methanol [190], acetone [191], acetic acid [192], dimethylformamide [193] or tetrahydrofuran [194] (Procedure 37, p. 214). 

The racemic polyzonimine (19) is prepared as shown in Scheme 33. The expoxide (314) is rearranged to the aldehyde (315) by refluxing with LiBr-HMPA in benzene. Morpholine enamine (316) derived from 315 is condensed with nitroethylene, generated in situ from 2-acetoxynitroethane, to afford the nitroaldehyde (317). Ethylene acetalization, reduction over Raney nickel, and subsequent deacetalization give ( )-polyzonimine (19) in 22% overall yield from the epoxide (314) 113). 

B. Acetaldehyde From Methyl Acetate Reductive Carbonylation. A... 

Saturated Ketones and Ketol Acetates. Reductive Alkylation / 27 Mechanism of reduction / 27 Stereochemistry of reduction / 34 Side reactions in reductions / 37... 

An interesting asymmetric Baeyer-Villiger reaction of prochiral ketones via chiral ketals (9) allowed the synthesis of chiral 3-butyrolactones in ees of up to 89%.167 An SnCU mCPBA ratio of >1 in dichloromethane at —100 °C gave the best results and this is attributed to a high 5k 1 character due to lowered nucleophilicity of peracid by coordination to S11CI4. This is mirrored by die beder selectivity of BH3 dian EtjSiH in acetal reductions. 

A. A. Aristidou, G. N. Bennett, and K. Y. San, Metabolic engineering of Escherichia coli to enhance recombinant protein production through acetate reduction, Biotechnol. Progr. 1995, 375-478. 

Lewis acid-assisted cleavage diester -J of the acetal reduction... 

Like the cuprous reduction in pyridine, silver acetate reduction is pro-... 

Sfl-Acetals. Reduction of alkylthiomethyleniminium salts with 1 in THF at 0° results in S,N-acetals (2) as the major product. Reduction of these salts with LiAlH4 or NaBH4 results in tertiary amines or a mixture of 2 and the corresponding tertiary amine.1... 

Cyclization of bromo acetals. Reduction of the unsaturated bromo acetal 1 with BusSnH (AIBN) gives the cyclic acetal 2, which is converted on Jones oxidation to the rrany-lactone 3. 

Ethers from acetals. Reduction of acetals with trimethylsilane (or tri-ethylsilane) catalyzed by trimethylsilyl trifluoromethanesulfonate gives ethers in 75-95% isolated yield (equation I). 

Carbopenams, The 0-lactam 1 is cyclized to a bicyclic -lactam (2) by reaction with a number of electrophiles (I2, C6H,SBr), but highest yields are obtained with mercury(II) acetate. Reduction of 2 leads to 3, which has the ring skeleton of the thienamycin antibiotics. ... 

The direct oxidation of the tr-adduct 1 with bromine, A -bromosuccinimide or, preferably, lead tetraacetate in the presence of acetic acid afforded jS-acetoxy amines 2 by an overall syn addition. The acetate reduction with lithium aluminum hydride gave the corresponding )S-hy-droxy amines 360 62. 

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