Ketones aliphatic hydroxyketones

By similar procedures diazirines were prepared not only from simple aliphatic ketones but also from hydroxyketones and )3-aminoketones (B-67MI50800), and so were a large number of diazirines from steroidal ketones (65JA2665). Permanganate, bromine, chlorine and hypochlorite were used as oxidants. A one-step preparation of diazirines from ketones like 3-nonanone, ammonia and chlorine has been claimed in a patent (66USP3290289). 3,3-Diazirinedicarboxylic acid derivatives like (286) were obtained directly from oxime tosylates by the action of two moles of O-ethoxyamine (81AG(E)200). 

Extensive studies by Corey have clearly revealed the wide range of applications of the CBS reduction [2]. However, recent observations of high enantioselectivity in the reduction of several a-hetero substituted aliphatic ketones catalyzed by 1 are worthy of mention (Scheme 2). A series of aliphatic a-hydroxyketones protected with tetrahydropyranyl [7], trialkylsilyl [12], and sulfonyl groups [8] as well as p-ketosulfones [9] were reduced to give the corresponding alcohols in up to >99% ee. 

Polymer 149, prepared by ring-opening polymerization (ROMP) of the corresponding functionalized norbornene, provides a clear illustration of the potential of this kind of materials. This resin catalyzes (12% molar) the reaction of linear aliphatic aldehydes with unsaturated ketones to provide 1,4-dicarbonyl compounds (153, Scheme 10.23) and was used for four consecutive cycles without any detectable decrease in performance [358]. A similar dimethylthiazolium structure supported on 2% cross-linked PS-DVB (150) was studied as catalyst for the acyloin condensation of a large variety of aldehydes [364], Catalyst 150 is used in 10 mol.% and the reaction takes place in ethanol at room temperature, with triethylamine as the base, to afford the corresponding a-hydroxyketones in excellent yields. Remarkably, the catalyst can be reused 20 times without losing its activity. 

Alkanones (C3-C15) have been found in the volatile fractions of many fruits and foodstuffs, but they do not contribute significantly to their aroma. An exception are the odd-numbered methyl ketones C7, C9, Cn which possess a characteristic nutty note they are used, e.g., in cheese flavor compositions. In perfumery, aliphatic ketones are used for accentuation, e.g., 3-octanone [106-68-3] for lavender notes. The hydroxyketone acetoin and the diketone 2,3-butanedione are commercially important aroma substances. 

In addition to the reduction of ketones (e.g., aromatic and aliphatic ketones, a-halo ketones, hydroxyketones, enones, and ketoesters), oximes can be reduced to the corresponding amine with this reagent. In general, ketone oxime ethers, such as 39, can give rise to amines 40 in excellent chemical yield with good to excellent optical purity.5d... 

As the intermediate enamine reacts faster with imines than aldehydes, a one-pot three component coupling of the donor ketone, aldehyde and amine is possible. List and coworkers have achieved high ees in this reaction utilising L-proline (7.66) and some aliphatic aldehydes and aromatic aldehydes such as (7.136) in combination with p-anisidene (7.137). This catalyst system is also effective for the coupling of a-hydroxyketones. Use of the tetrazole-substituted proline (7.80) allows the reaction to be performed in dichloromethane rather than DMSO and high ees in the Mannich reaction between aliphatic ketones and imines derived from ethyl glyoxalate have been obtained imder these reaction conditions. 

Besides the aldol reaction to form y0-hydroxyketone, 1,3-Dipolar Cycloaddition can also form similar molecules. In addition to the Mukaiyama Aldol Reaction, the following are also similar or closely related to the aldol reaction the Claisen-Schmidt Condensation (the aldol reaction between benzaldehyde and an aliphatic aldehyde or ketone in the presence of relatively strong bases to form an o, )0-unsaturated aldehyde or ketone), the Henry Reaction (base-catalyzed addition of nitroalkane to aldehydes or ketones), the Ivanov Reaction (the addition of enediolates or aryl acetic acid to electrophiles, especially carbonyl compounds), the Knoevenagel Reaction (the condensation of aldehydes or ketones with acidic methylene compounds in the presence of amine or ammonia), the Reformatsky Reaction (the condensation of aldehydes or ketones with organozinc derivatives of of-halo-esters), and the Robinson Annulation Reaction (the condensation of ketone cyclohexanone with methyl vinyl ketone or its equivalent to form bicyclic compounds). 

The chemoselective enolate formation from hydroxyketone (245) and isomerizable aliphatic Ai-Dpp imines (246) has been described. The Et2Zn/linked-BINOL complex (247) effectively promoted the Mannich-type reaction, affording P-alkyl-P-amino-a-hydroxy ketones (248) in high enantioselectivity and good yield (Scheme 100). ... 

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