Nitroethanol synthesis

Thus, the 2-nitroethanol synthesis results in the addition of two carbon atoms to an aldose sugar to produce two higher-carbon ketose sugars epimeric at carbon 3. While the synthesis is general in nature, the two ketoses produced from any one aldose are seldom as readily separable as is fortunately the case with D-mannoheptulose and D-gluco-heptulose. However, the newly developed techniques of adsorption and partition chromatography will undoubtedly be of service for the more difficult separations. 

D-manno-Heptulose also may be prepared readily from D-arabinose by the nitroethanol synthesis (see p. 111). 

The use of silylketals derived from allylic alcohols and 1-substituted nitroethanols for the stereocontrolled synthesis of 3,4,5-trisubstituted 2-isoxazolines via intramolecular 1,3-dipolar cycloaddition has been demonstrated. Here again, the use of silyl nitronates (ISOC) increases the level of selectivity compared to INOC (Eq. 8.92).145... 

The reaction of a -halocarboxylic acids with sodium nitrite has been used to synthesize ni-tromethane, nitroethane and nitropropane, although the reaction fails for higher nitroalkanes. " A number of other reactions have been reported which use nitrite anion as a nucleophile, including (1) reaction of alkyl halides with potassium nitrite in the presence of 18-crown-6, (2) reaction of alkyl halides with nitrite anion bound to amberlite resins, (3) synthesis of 2-nitroethanol from the acid-catalyzed ring opening of ethylene oxide with sodium nitrite, and (4) reaction of primary alkyl chlorides with sodium nitrite in the presence of sodium iodide. ... 

The jyn-selective asymmetric nitroaldol reaction was successfully applied to the catalytic, asymmetric synthesis of ftireo-dihydrosphingosine (94), which elicits a variety of cellular responses by inhibiting protein kinase C (Figure 22).44 The nitroaldol reaction of hexadecanal 92 with 3 equiv. of nitroethanol (86) in the... 

Extension and elaboration of the original nitromethane work continued to occupy the attention of Sowden and his collaborators until his death. A convenient synthesis of 2-deoxy-D-er2/f/tro-pentose was a particularly noteworthy achievement, and the substitution of 2-nitroethanol for nitromethane opened the door to the ketoses. The addition of sodium meth-oxide or ammonia to C-nitro-olefins also provided convenient means for preparing 2-0-methyl derivatives and 2-amino sugars, respectively. 

Breau and co-workers reported diastereoselective INOC and ISOC reactions of silaketals 205 derived from allyUc alcohols and nitroethanols for the synthesis of 3,4,5-trisubstituted 2-isoxazolines 206 (Scheme 50) [152,153]. 

Nitroethanol was recently employed as C/O bis-nucleophile by Hayashi and coworkers [38] for the synthesis of optically active functionalized tetrahydropyrans by reaction with enals using diphenylprolinol silyl ether as the organocatalyst (Scheme 16.18). The diastereoselectivity of the Michael/acetalization sequence was improved by isomerization to the thermodynamically more stable trans isomers upon basic treatment. 

In spite of its relative instability nitroethylene (pure compound readily decomposes at r.t., but is stable in benzene solution over months ) is conveniently produced in kilo-quantities by dehydration of 2-nitroethanol according to the method outhned in the proposed synthesis of TM 2.19 (Scheme 2.42) [26]. 

Example 9.3 Structure and stereochemistry of the antibiotic (—)-chloramphenicol is presented in (lf ,2/ )-TM 9.2. Propose the retrosynthesis of racemic TM 9.2 neglecting absolute configurations at stereogenic centers and then suggest the synthesis from benzaldehyde and 2-nitroethanol and propose the simple synthesis of 2-nitroethanol. Indicate a reaction step that can be completed diastereo- and enantioselecti vely ... 

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