Amino alcohols nitro aldehydes

Reaction With Carbonyl Compounds. Primary and secondary nitroparaffins undergo aldol-type reactions with a variety of aldehydes and ketones to give nitro alcohols (11). Those derived from the lower nitroparaffins and formaldehyde are available commercially (see Nitro alcohols). Nitro alcohols can be reduced to the corresponding amino alcohols (see Alkanolamines). 

Novel chiral thiolated amino alcohols have been recently synthesised and then evaluated by Vilaivan el al. as a potential new class of ligands for Cu-catalysed nitroaldol reactions. Amino alcohol ligands bearing Ai-(2-alkyl-thio)benzyl substituents provided only modest enantioselectivities (22-46% ee) while those carrying Al-2-thienylmethyl substituents provided better enantioselectivities of up to 75% ee for the nitroaldol reaction between p-nitro-benzaldehyde and nitromethane. A range of aromatic aldehydes were acceptable substrates giving moderate to high enantioselectivities of up to 88% ee, as shown in Scheme 10.32. 

They react with a wide range of aliphatic and aromatic aldehydes in the presence of catalytic amounts of tetrabutylammonium fluoride (TBAF) to give the trialkylsilyl ethers of P-nitro alcohols with high anti-selectivity (98%). The diastereoselective Henry reaction is summarized in Table 3.2. The products are reduced to P-amino alcohols using Raney Ni-H2 with retention of the configuration of P-nitro alcohols (Scheme 3.12). 

In nitro aldehydes both the nitro group and the aldehyde group are readily reduced by catalytic hydrogenation. It may be difficult, if not impossible to hydrogenate either function separately. More dependable methods are reduction by alane [787] or by isopropyl alcohol and aluminum isopropoxide Meerwein-Ponndorf) [788] to nitro alcohols, and by stannous chloride [789, 790], titanium trichloride [590] or ferrous sulfate [218] to amino aldehydes Procedure 38, p. 214). 

Though not available commercially, trifluoronitroethane shows some interesting chemistry consistent with the powerful electron-withdrawing effect exerted by the nitro group. Fluoride-mediated nitroaldol reactions were reported [144] with aldehydes affording a valuable entry to trifluoromethyl amino alcohols... 

Nitro-aldol reaction (9, 444).5 The /J-amino alcohol obtained hy fluoride ion catalyzed a Idol condensation of aldehydes with silyl nitronales (1) is the practically pure (RS,SR)-diastereoisomer (3),... 

The lower members of the homologous series of 1. Alcohols 2. Aldehydes 3. Ketones 4. Acids 5. Esters 6. Phenols 7. Anhydrides 8. Amines 9. Nitriles 10. Polyhydroxy phenols 1. Polybasic acids and hydro-oxy acids. 2. Glycols, poly-hydric alcohols, polyhydroxy aldehydes and ketones (sugars) 3. Some amides, ammo acids, di-and polyamino compounds, amino alcohols 4. Sulphonic acids 5. Sulphinic acids 6. Salts 1. Acids 2. Phenols 3. Imides 4. Some primary and secondary nitro compounds oximes 5. Mercaptans and thiophenols 6. Sulphonic acids, sulphinic acids, sulphuric acids, and sul-phonamides 7. Some diketones and (3-keto esters 1. Primary amines 2. Secondary aliphatic and aryl-alkyl amines 3. Aliphatic and some aryl-alkyl tertiary amines 4. Hydrazines 1. Unsaturated hydrocarbons 2. Some poly-alkylated aromatic hydrocarbons 3. Alcohols 4. Aldehydes 5. Ketones 6. Esters 7. Anhydrides 8. Ethers and acetals 9. Lactones 10. Acyl halides 1. Saturated aliphatic hydrocarbons Cyclic paraffin hydrocarbons 3. Aromatic hydrocarbons 4. Halogen derivatives of 1, 2 and 3 5. Diaryl ethers 1. Nitro compounds (tertiary) 2. Amides and derivatives of aldehydes and ketones 3. Nitriles 4. Negatively substituted amines 5. Nitroso, azo, hy-drazo, and other intermediate reduction products of nitro com-pounds 6. Sulphones, sul-phonamides of secondary amines, sulphides, sulphates and other Sulphur compounds... 

The asymmetric catalytic nitroaldol reaction, also known as the asymmetric Henry reaction, is another example of an aldol-related synthesis of high general interest. In this reaction nitromethane (or a related nitroalkane) reacts in the presence of a chiral catalyst with an aldehyde, forming optically active / -nitro alcohols [122], The / -nitro alcohols are valuable intermediates in the synthesis of a broad variety of chiral building blocks, e.g. / -amino alcohols. A highly efficient asymmetric catalytic nitroaldol reaction has been developed by the Shibasaki group, who used multifunctional lanthanoid-based complexes as chiral catalysts [122-125],... 

Nitroalkanols are intermediate compounds of /1-amino alcohols that are used extensively in many important syntheses. They are obtained by Henry s reaction through the condensation of nitroalkanes with aldehydes. Different nitro compounds have been reacted with carbonyl compounds in reactions catalysed by alkaline earth metal oxides and hydroxides/621 Among the catalysts examined, MgO, CaO, Ba(OH)2, and Sr(OH)2, exhibited high activity for the reaction of nitromethane with propionaldehyde. The yields were between 60 % (for MgO) and 26 % [for Sr(OH)2] at 313 K after 1 h in a batch reactor. The study of the influence of the pretreatment temperature of the solid showed that for MgO and CaO a... 

The reaction of 5-amino-l,2,4-thiadiazoles (16) with aldehydes produces a-amino alcohols (145), azomethines (146) or bis-amines (147) depending on the reactants and reaction conditions, as illustrated in Scheme 58. The nitration of 5-amino-3-methyl-l,2,4-thiadiazole (25) in a mixture of 98% sulfuric acid and 95% nitric acid at 0°C is reported to produce (148) in good yield (65AHC(5)119), but a similar reaction with 3-amino-l,2,4-thiadiazoles has not been described. Products of type (149) can be obtained, however, by the ring closure of Af-nitro-AT-thiocarbamylguanidines with alkaline hydrogen peroxide. 

Sitro-aldol reaction fl-amino alcohols. Primary nitro compounds form silyl nitronates (1) when treated in sequence with LDA (THF, -78°) and then a silylating reagent. These silyl nitronates undergo aldol condensation with aldehydes in the presence of tetra-n -butylammonium fluoride (there is no reaction in the absence of the catalyst). The products 2 are reduced to /3-amino alcohols (3) in good yield by lithium aluminum hydride (equation 1). Secondary nitroalkanes undergo the same reaction sequence, but the silyl nitronates are less stable and are obtained in only... 

Aliphatic nitro alcohols, conveniently derived by the condensation of nitroparaffins with aldehydes, are reduced to amino alcohols in almost quantitative yields by the action of iron powder and mineral acid. Best results are obtained when an excess of acid is present. The procedure is illustrated by the synthesis of 2-amino-l-butanol (90%). ... 

The nitrile group can be selectively hydrogenated in the presence of aldehydes, ketones but not in the presence of olefins, acetylenes, and nitro groups. Cyanohydrins are reduced to amino alcohol mostly over platinum oxide in acetic acid . 

Lactonization Isomerization Oxidation of alcohols to aldehydes ketones Reduction of aldehydes and ketones to alcohols Oxidation of amino groups to nitro groups Hydrolysis of nitriles to amides and caibo Q lic acids Functional group alteration... 

Scheme 24 depicts a synthesis of functionalized trisubstituted olefins from [(trimethylsilyl)acetyl] trimethylsilane " this intermediate and other related acylsilanes can be prepared from silylacetylenes via a hydroboration-oxidation sequence. A stereoselective synthesis of /8-nitro- (and subsequently /3-amino-) alcohols reported this year proceeds as shown in Scheme 25, although the same O-silylated nitroalcohol intermediates can be obtained by the addition of aldehydes R CHO to silyl nitronates R CH=N02SiR3. These latter com-... 

A negative reaction is given by hydrocarbons, alkyl halides, aldehydes, ketones, ethers, amino acids, nitro compounds, and nitriles. The test is suitable for the detection of alcohols in other solvents. 

The nitroaldol (Henry) reaction provides 1,2-nitro alkanols under atom-economical proton transfer conditions, which allows for easy access to highly versatile 1,2-amino alcohols (Scheme 6) [31]. A number of catalytic systems have been devised to render this useful C-C bond-forming reaction asymmetric however, diastereoselectivity remained a longstanding problem, in particular for a ri-selective reactions [14, 32, 33]. syw-Selective reaction can be achieved by a monometalhc catalytic system as shown in Fig. 9a, where both an aldehyde and a nitronate coordinate to the metal center to give syn product due to steric repulsion [34—36]. To make the reaction proceed in fluft-selective manner, different strategy in catalyst design is required [37, 38]. Simultaneous activation of both the aldehyde and the nitronate in an anti-paraUel fashion can afford the anti-1,2-nitro alkanols preferentially (Fig. 9b). To attain the a ri-paraUel transition state, a heterobimetalhc catalyst offers a suitable... 

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