Phenylglyoxal monohydrate

Reaction of (25,55)- and (2i ,55)-2-[5-(terc-butyldimethylsilyloxy)piper-idin-2-yl]ethanols with phenylglyoxal monohydrate in the presence of 4 A molecular sieves in boiling CH2CI2 overnight gave (15,4n5,7i )- and (2i ,4ni ,7i )-l-benzoyl-7-(terc-butyldimethylsilyloxy)perhydropyrido[l,2-c][l,3]oxazines 97 and 100, respectively, in good yield (99MI19). Both products were accompanied by unidentified minor isomers. 

Diastereoselective Alkylation of Chiral Keto- and Formylaminals. Diamine (1) forms a chiral ketoaminal by condensation with phenylglyoxal monohydrate. Diastereoselective addition of a Grignard reagent to the ketoaminal and subsequent hydrolysis affords optically active t-a-hydroxyaldehydes with >94% ee (eq 2). Various... 

Mannich-type reactions of aldehydes, amines, and vinyl ethers proceeded smoothly in the presence of a catalytic amount of Sc(OTf)3 in aqueous media (Eq. 20) [69]. Commercially available aqueous solutions of formaldehyde and chloroacetaldehyde were used directly and the corresponding /3-amino ketones were obtained in good yields. Phenylglyoxal monohydrate, methyl glyoxylate, an aliphatic aldehyde, and an a,/3-unsaturated aldehyde also worked well to give the corresponding /3-amino esters in high yields. 

The use of Ln(OTf)3 in the activation of aldehydes other than formaldehyde was also investigated [18], Several examples of the present aldol reaction of silyl enol ethers with aldehydes are listed in Table 14-1. In every case, the aldol adducts were obtained in high yields in the presence of a catalytic amount of Yb(OTf)3, Gd(OTf)3, or Lu(OTf)3 in aqueous media. Diastereoselectivities were generally good to moderate. One feature in the present reaction is that water-soluble aldehydes, for instance, acetaldehyde, acrolein, and chloroacetaldehyde, can be reacted with silyl enol ethers to afford the corresponding cross aldol adducts in high yields (entries 5-7). Some of these aldehydes are commercially supplied as water solutions and are appropriate for direct use. Phenylglyoxal monohydrate also worked well (entry 8). It is known that water often interferes with the aldol reactions of aldehydes with metal enolates and that, in the cases where such water... 

Simple imines undergo Diels-Alder reactions in the presence of suitable catalysts. Lanthanide triflates, which are stable in water, are especially effective. Thus in the presence of 10 mol% of ytterbium or scandium triflate, Danishefsky s diene 4 reacts with benzylideneaniline in acetonitrile at 0 °C to give the dihydropyridone 76 quantitatively (equation 50) analogous products are obtained from 4 and furylideneaniline, benzyli-denebenzylamine and pentyIidenebenzylamine. In a one-pot version of the reaction, a mixture of an aldehyde, an amine and the diene 4 in acetonitrile containing magnesium sulfate is treated with 10 mol% ytterbium triflate to afford the dihydropyridone in ca 80% yield. Even phenylglyoxal monohydrate can be employed. ... 

Phenylglyoxal monohydrate also worked well in this reaction. The imine derived from phenylglyoxal is unstable and a troublesome treatment is known to be required for its use [43]. 

Phenylglyoxal monohydrate 160, ketoesters and urea in three-component Biginelli reachon furnished DHPMs 161 (R = Me, OMe or OEt) (Scheme 61). The ketone of 161 provided a potential site for further transformations (05J1CS319). 

A number ofpyrazolo[3,4-f>]pyridines are formed by a domino reaction of anilines, arylglyoxal monohydrates, and pyrazol-5-amines (Scheme 8). Methyl or chloro-substituted phenylglyoxal monohydrate could be used to form the fused pyridines in moderate yields. While some variation was also tolerated on the pyrazoles, ort/io-substitution on the anilines was not conducive to the reaction (14CC6108). 

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