Acylated amidines

Cyclische N-Acyl-amidine werden dagegen mit guten Ausbeuten iiber die N,N-Acetale zu Aminen gespalten z. B.5 ... 

Although mostly amide derivatives have been exemplified, acyl amidines are also claimed, e.g. the dimethylaminoethylidene (57), with an IC50 of 4.4 nM against OT and 20-fold and 67-fold selectivity over Via and V2 in a binding assay [115]. 

Action of hydroxylamine on N-acylated amidines, iminochlorides and iminoethers [C]... 

Bei der kalalytischen Hydrierung mit Wasserstoff und Palladium/Kohlenstoff als Katalysator wird die schwache N,0-Bindung des Ringes aufgebrochen, so daB man als isolierbare End-produkte N-Acyl-amidine erhalt277,286-292 z.B. ... 

Hydrogenolytic ring opening of the 5-substituted 1,2,4-oxadiazole ring of 3-(l,2,4-oxadia-zol-3-yl)pyridin-2-amines 5 in the 3-position creates a C-N -C side chain in the form of an acylated amidine 6. In refluxing xylene this cyclizes with the amino group in the 2-position to yield pyrido[2,3-c/]pyrimidin-4-amines 7.9... 

Cyclic amidines are prepared by alkylation of acylic amidines [16]. Bromoamination of olefins by A-bromosuccinimide (NBS) and cyanamide (NH2CN) affords p-bromoalkyl-cyanamides. Chemoselective hydrogenation of the nitrile function leads to acyclic amidines followed by spontaneous cyclization to yield cyclic amidines, which are hydrolyzed under basic condition to give 1,2-diamines (Scheme 3.5). 

Another approach uses the reaction of 6-chloro-5-nitropyrimidines with a-phenyl-substituted amidines followed by base-catalyzed cyclization to pteridine 5-oxides, which can be reduced further by sodium dithionite to the heteroaromatic analogues (equation 97) (79JOC1700). Acylation of 6-amino-5-nitropyrimidines with cyanoacetyl chloride yields 6-(2-cyanoacetamino)-5-nitropyrimidines (276), which can be cyclized by base to 5-hydroxypteridine-6,7-diones (27S) or 6-cyano-7-oxo-7,8-dihydropteridine 5-oxides (277), precursors of pteridine-6,7-diones (278 equation 98) (75CC819). 

A convenient synthesis of trisubstituted 1,3,5-triazines uses acylamidines 1 and amidines < 95JOC8428 >, whilst l,3,5-triazin-2(l/f)-ones 3 are obtained from N-acyl-lV -carbamoyl-S-methylisothioureas 2 <96H(43)839>. 

Dimethyl ami no)-2-azaprop-2-en-l-yl ideneldimethylammonium chloride ("Gold s reagent"),4 the preparation of which Is described in part A of the procedure, is a general B-dimethylaminomethylenating agent which reacts successfully with amines (eq. 1) to produce amidines, with ketones (eq. 2) to produce enaminones,6 and with amides (eq. 3) to product acyl ami dines. ... 

Barker, P. L. Gendler, P. L. Rapoport, H. Acylation of Dibasic Compounds Containing Amino Amidine and Aminoguanidine Functions, J. Org. Chem. 1981, 46, 2455-2465. 

Bader has described the first preparative route to 1,3,5-triazines containing three different alkyl or aryl substituents (65JOC702). The initial step is the formation of an acyl imidate (162) followed by condensation with an amidine to give the product (Scheme 100). Although mixtures are formed, the method is valuable because such triazines are otherwise very difficult to prepare. Typical examples are given in Table 19. 

Several strategies enable the attachment of guanidines and amidines to insoluble supports (Figure 3.29, Table 3.28). These include attachment as A-benzyl, A-acyl, and A-alkoxycarbonyl derivatives. Furthermore, support-bound isothioureas can be used to convert amines into guanidines. The synthesis of support-bound guandines is considered in Section 14.3. 

Thioamides are suitable intermediates for the preparation of amidines, thiazoles, and thiophenes. Thioamides have mainly been prepared on insoluble supports by C-acylation of enamines or C,H-acidic compounds with isothiocyanates (Entries 1-3,... 

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