Aldehydes Amido-compounds

Perfluoroalkyl- and perfluoroaryltitanium compounds were prepared m situ via reaction of the corresponding Gngnard reagents with chlorotris(diethyl-amido)titanium [28S] Reaction of the titanium compounds with aldehydes resulted in fluoroalkylative amination [288] (equation 192)... 

A completely different product class, a-amido, (3-hydroxy carboxylic acids, can be obtained from the [2+2]-photocycloaddition of aldehydes to 5-methoxyoxazoles and subsequent hydrolysis of the bicyclic oxetanes [3]. Compound 3 is available from the triplet benzaldehyde addition to dimethyl 5-methoxyoxazole in diastereomerically pure (erythro-selective) form. 

Imidazoles.—Formation. Several new syntheses of imidazoles from isocyanides have been reported these include the formation of 1-alkyl-imidazoles (396) by the action of primary amines on 2-isocyano-2-tosylstyrene, PhCH=C-(NOTos, the cyclization of the enamine Me2NCH=C(NC)C02Me to compound (397) in the presence of methyl iodide,and the preparation of the ethers or thioethers (398) from isocyano-cyanides R CH(NC)CN by their reaction with alcohols or thiols R XH, respectively.Aromatic aldehydes are converted into 2-aryl-4,5-dichloroimidazoles (399) by the combined action of cyanogen and hydrochloric acid. 5-Acetyl-4-methylimidazole (400) results when form-amido-acetylacetone, AC2CHNHCHO, is heated with formamide and formic acid. Exhaustive chlorination of tetramethyldithio-oxamide leads to the tri-chloro-imidazolium cation (401). ... 

Kanai and colleagues developed an enantioselective synthesis of various 2-(2-hydroxyethyl)indole scaffolds via the amido-cupration of allenes followed by the asymmetric addition of carbonyl compounds. Treatment of allene 88 with a copper catalyst forms a stable and highly nucleophilic allyl-copper species, which then adds into benzaldehyde (89) to furnish indole 90. A range of carbonyl compounds are competent in the sequence, including aryl- and heteroaryl aldehydes, alkyl aldehydes, and aryl ketones. This is reported to be the first example of a combined catalytic indole generation and subsequent enantioselective addition of carbonyl compormds (14CS1585). 

In order to obtain more selective anion receptors we introduced substituents to the salene moiety which contain amido groups. Compounds 23 and 24 were prepared by reaction of the corresponding aldehydes and cu-1,2-cyclohexanediamine in the presence of uranyl acetate [U02(0Ac)2.2H20] in methanol in 50-75% yield [ref 39]. 

The anions, generated in situ by desilylation of silylacetylenes, allylsilanes, propargylsilanes, a-silyloxetanones, bis(trimethylsilylmethyl) sulfides, and other silane derivatives,can undergo nucleophilic addition to ketones and aldehydes (eq 11). Al-(C,C-bis(trimethylsilyl)methyl) amido derivatives can add to aldehydes followed by Peterson alkenation to form acyl enamines. Treatment of 2-trimethylsilyl-l,3-dithianes can generate dithianyl anions, which are capable of carbocyclization via direct addition to carbonyl or Michael addition (eq 12). The fluoride-catalyzed Michael additions are more general than Lewis acid-catalyzed reactions and proceed well even for those compounds with enolizable protons and/or severe steric hindrance (eq 13). ... 

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