Hydantoins azomethines

The oxidation of phenylhydrazine and 1,2-disubstituted hydrazines to hydrazones and diazenes by CI2C proceeds via formation of unstable azomethine imines.95 The conversion of alcohols into alkyl halides is achieved by reaction with CCI4 (or CBr4) in DMF under electrochemical reduction.96 The reaction of dihalocarbene X2C with DMF to form a Vilsmaier reagent (93) is proposed as the key process. The reaction of simple isocyanates (RNCO) with dimethoxycarbene normally gives hydantoin-type products. In the reaction with vinyhsocyanates such as (94), however, hydroindoles (95) are formed in good yields.97... 

Fluorous aminoesters have also been used in DOS of three unique triaza tricyclic and tetracyclic ring systems (Scheme 22) [44], Bicyclic pyrrolidines 12 generated from one-pot, three-component 1,3-dipolar cycloaddition of azomethine ylides were further converted to hydantoin-, piperazinedione-, and benzodiazepine-fused compounds 31-33, respectively. Each of these three heterocyclic scaffolds has four stereocenters on the central pyrrolidine ring and up to four points of diversity (R1 to R4). The structure of compound... 

The Bucherer-Bergs synthesis is of general application to carbonyl compounds, employing potassium cyanide and ammonium carbonate.1,4 Carbonyl derivatives such as semicarbazones, thiosemicarbazones, oximes, azines, phenylhydrazones, imidazolidines, and azomethines also are readily converted directly to the corresponding hydantoins 44 The extent to which the reaction occurs appears unrelated to the hydrolytic stability of the starting material. The proposed mechanism is given in Scheme 1. 

A large number of azomethine nitrofurans containing various heterocyclic rings have been synthesized the most important of these contain either a hydantoin Table 6.5) or oxazolidinone Table 6.6) ring. Nitrofurans containing the following rings have also been studied 3-oxazolidin-2-one... 

Aq. K-cyanate treated with cyclohexylcarboxaldehyde and p-tolyl isonitrile in methanol, then n-dodecylamine hydrochloride added with stirring and icecooling, and the product isolated after 2 hrs. l-n-dodecyl-5-cyclohexyl-hydantoin 4-p-tolylimide. Y 1S%. F. e., also from azomethines, s. I. Ugi and K.Offermann, B. 97, 2276 (1964). 

A related method was applied to the synthesis of 18 isoxazolothiohydantoins (Scheme 11.51)/ Hydantoin formation was also applied to the release of proline derivatives that were obtained from the intramolecular cycloadditions of resin-bound azomethine ylides and alkenes. ... 

Y.-D. Gong, S. Nadji, M. M. Olmstead, M. J. Kurth, Solid-phase synthesis Intramolecular azomethine ylide cycloaddition ( proline) and carbanilide cyclization (—> hydantoin) reactions. J. Org. Chem. 1998, 63, 3081-3086. 

Zhang et al. (2006) have reported an advance fluorous synthesis of hydantoin-, piperazinedione-, and benzodiazepinedione-fused tricyclic and tetracyclic ring systems using a sequence of microwave-assisted, fluorous multicomponent reactions (F-MCRs) and fluorous solid-phase extractions (F-SPEs). They used microwave-assisted one pot, three-component [3+2] cycloaddition of azomethine ylides with... 

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