Cyclic guanidine derivatives

Scheme 16 Multicomponent synthesis of cyclic guanidine derivatives...

Taylor and co-workers <99SL795> repotted some promising results with DBU-like cyclic guanidine derivatives of type 44, equipped with the appropriate chiral auxiliary. Both yields and ee s were modest, but the ready availability of the amine, and the flexibility of substitution on the... 

Related intramolecular aminomercurations of cyclic guanidine derivatives have been studied in some detail,2 0 but are primarily useful for the synthesis of bicyclic heterocycles (equations 127 and 128). Cy-clizations of allylic isothiouronium salts have also been reported (equation 129).260b,260e... 

Patent Cyclic Guanidine Derivatives and Their Use as Pesticides... 

The power of cyclic chiral nitrones in synthesis was demonstrated by Nagasawa et al. (52) by the synthesis of the enantiomerically pure pentacyclic guanidine derivative 38 (Scheme 12.14). The 1,3-dipolar cycloaddition of 27b with 34 took... 

Thermal stability of a number of cyclic and acyclic nitramines, amine nitrate salts and guanidine derivatives [34]. 

Dinucleophilic amidines and guanidines can be condensed with aminomethylenediones to give pyrimidines (equation 210). In the case of cyclic diketo derivatives quinazolinediones are obtained284. 

Method of choice for synthesis of 1,5,9-triazacyclododecane 7 and some of its C-substituted derivatives is a ring closure on a guanidine derivative (Scheme 7). The method mostly gives reasonable yields and cyclic aminal can serve as a protective group. 

Chloro-l,3-dimethylimidazolium chloride (DMC) [26] (R =R = Me, L = H in 11, Scheme 4.8a) not only acts as a powerful dehydration agent but also has unique and versatile abilities to chlorinate primary alcohols, to oxidize primary and secondary alcohols and to reduce sulfoxides and so on. In addition, DMC easily reacts with amines to yield the corresponding guanidines. Thus, methods of preparing monocyclic and bicyclic systems by application of DMC chemistry in the key steps have been developed [27] the reaction of DMC-type chloroamidine compounds with amines for trisubstituted mono-cyclic guanidines [27a] (Scheme 4.8a), the intramolecular cyclization of thiourea derivatives after activation with DMC for monosubstituted or disubstituted monocyclic and bicyclic guanidines [27b] (Scheme 4.8b), and the DMC mediated cyclization of... 

The rates of methanolysis of several benzimidazolides (80), cyclic amidine derivatives (81)-(83), 2-aminopyridine derivatives (84)-(86), and the guanidine derivative (87) have been... 

The methodology can be utilized in the preparation of quite complex derivatives such as the bicyclic guanidine outlined in Equation (1). In this example, in a one-pot reaction, 2-(o-azidophenyl) ethylamine and an o-azidoaryl carbonyl compound react to form the corresponding imine which upon subsequent treatment with triphenylphosphine and an arylisocyanate affords the cyclic guanidine (29) in a consecutive aza-Wittig/(27t -b 2n) cycloaddition/transannular annelation reaction sequence. 

Hexazinone is a representative of another family of herbicidal 1,3,5-triazines, which are characterized by the presence of a cyclic urea feature. It may be synthesized as in Scheme 11.3 by condensing guanidine derivative 11.1 and cyclohexyl isocyanate to form intermediate 11.2, which is then cyclized by the NH-to-ester condensation found frequently in pyrimidine synthesis to give hexazinone (11.3). 

Amidines and cyclic amidines are also converted into 1,2,4-thiadiazoles by reaction with isothiocyanates, imino-sulfenyl chlorides, di- and trichloromethyl sulfenyl chlorides, and carbon disulfide in the presence of sulfur. Ureas, thioureas, guanidines, carbodiimides, and cyanimides react with chlorocarbonylsulfenyl chloride to produce 1,2,4-thiadiazol-5-one derivatives in another example of a type B synthesis <1996CHEC-II(4)307>. 

The reaction works well when R and are alkyl or benzyl, or when NR R is a cyclic secondary amine. ° It also works with benzil and its para-substituted derivatives and with guanidine and its mono-substituted derivatives, giving high yields of products 35 having Ar = phenyl para-substituted with H, Cl, Me, and MeO, and R = R = R = H,... 

These compounds, cyclic derivatives of urea or guanidine, are as follows ... 

Note The following derivatives of ethylene guanidine apparently are capable of being isolated in the isomeric forms indicated, plus A(i) mino-or nitra (i) minoethyl guanidines (non-cyclic) not indicated, depending upon pH, thermal and temporal history of their method of prepn... 

Azirine derivatives 318 were shown in the same article to be precursors of triazines 324 (30-35% yield) and pyrimidines 326 (30% yield) upon treatment in DMSO with guanidine and formamidine, respectively (Scheme 71). A similar pathway to that outlined above is also invoked to explain these results thus, intermediate 323 would yield 324 by electro-cyclic ring closure, whereas 326 would be formed by heterocyclization of 325 and loss of ammonia (91JOC7). 

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