Amidine Hydrochlorides Research Articles

Synthesis of N-Alkoxy Amidine Salts Via Addition of (N-Alkyl-N-Alkoxyammine)Dimethylaluminum Chlorides to Nitriles

: The addition of (N-alkyl-N-alkoxyammine)dimethylaluminum chlorides to nitriles provides a convenient route to little investigated N-alkoxy amidine hydrochlorides. A survey of the scope of this reaction is presented.

One-Pot Synthesis of 2-Aryl- and 2-Alkyl-pyrimidines

Reaction of 1,1,3,3-tetramethoxypropane with amidine hydrochloride salts at elevated temperatures in a sealed tube gave 2-substituted pyrimidines.

Electrochemical behavior of amidine hydrochlorides and amidines

The electrochemical behavior of N,N-dimethyl-N′-phenylformamidine hydrochloride was studied on a platinum electrode. The oxidation peak at +0.90 V vs. Ag/Ag+ 0.01 M (in CH3CN −0.1 M LiClO4) was assigned to the oxidation of the chloride anion. N,N-Dimethyl-N′-(4-chlorophenyl)formamidine and N,N-dimethyl-N′-(2-chlorophenyl)formamidine were isolated from the preparative electrolysis of this amidine hydrochloride. The electrochemical behavior of N-phenylbenzamidine hydrochloride and N-phenylcyclohex-3-enecarboxamidine hydrochloride was also studied at platinum and at vitreous carbon. Cyclic voltammetry of a number of amidines was performed. Only N-arylbenzamidines showed a reduction peak at potentials less negative than −3.0 V vs. Ag/Ag+ 0.01 M (discharge potential of the medium at vitreous carbon). Preparative electrooxidations of all amidines studied were unsuccessful because of strong and rapid passivation of the anode. Keywords: amidine, electrochemical oxidation, chloride, amidine hydrochloride.

Inverse Electron Demand Diels-Alder Reactions of Heterocyclic Azadienes: [4 + 2] Cycloaddition Reaction of Amidines with 1,3,5-Triazines

A detailed study of the scope of the amidine Diels-Alder reaction with 1,3,5-triazines is described. The thermal reaction of amidines with symmetrical 1,3,5-triazines proceeds with in situ amidine to 1,1-diaminoethene tautomerization, [4+2] cycloaddition with the 1,3,5-triazine, loss of ammonia from the initial Diels-Alder adduct with imine generation, imine to enamine tautomerization, and retro Diels-Alder loss of ethyl cyanoformate to provide substituted 4-aminopyrimidines in excellent conversions.The reaction proceeds best with the amidine hydrochloride salts at intermediate reaction temperatures (90-100 °C) in polar, aprotic solvents, is rather invariant to the ratio of dienophile-diene used, and is subject to triazine substituent effects characteristic of an inverse electron demand Diels-Alder reaction (R=CO 2 Et> R=H>> R=SCH 3 ). Notably, the generality of the amidine [4+2] cycloaddition reaction with 1,3,5-triazines which has been extented to include cyclic amidines effectively addresses the limitations of the alternative ynamine or N,O-ketene acetal dienophiles. A comparative examination of amidines, thioimidates, and imidates revealed that amidines are uniquely suited for use in this reaction cascade

ChemInform Abstract: Thieno Compounds. Part 8. Preparation of 3,4‐Dihydro‐4‐oxothieno‐(2,3‐d)pyrimidin‐2‐ylacetic Acid and ‐acetic Acid Derivatives.

AbstractCyclocondensation of the 2‐amino‐3‐thiophenecarboxylates (I) with ethyl cyanoacetate (II) in the presence of gaseous hydrogen chloride leads to the formation of the oxothieno(2,3‐d)pyrimidin‐2‐ylacetates (IV) via the amidine hydrochloride (III).

ChemInform Abstract: Preparation and Crystal Structure of 3‐(1‐Naphthylmethyl)‐3‐chlorodiazirine.

AbstractConversion of 1‐naphthylacetonitrile (I) to the corresponding amidine hydrochloride (III), followed by oxidation with sodium hypochlorite, yields the diazirine (IV).

Preparation of N,N,N′-tris(trimethylsilyl)amidines; a convenient route to unsubstituted amidines

The tris(trimethylsilyl)amidines RC(NSiMe 3)N(SiMe 3) 2 (R  C 6H 5, p-CH 3C 6-H 4, p-ClC 6H 4, p-MeOC 6H 4, p-Me 2NC 6H 4, p-CF 3C 6H 4, p-C 6H 5C 6H 4 and CF 3) are prepared by the reaction of the respective nitriles with (Me 3Si) 2NLi·OEt 2 in ether to give intermediates RC(NLi)N(SiMe 3) 2. Heating these intermediates with ClSiMe 3 in toluene affords the products, which are isolated by vacuum distillation, in high yield. With 1,4-dicyanobenzene, two equivalents of reagents affords the per(trimethylsilyl)-1,4-diamidine. Hydrolysis of the intermediates with 6 N ethanolic HCl affords the unsubstituted amidine hydrochlorides RC(NH)NH 2·HCl (R  C 6-H 5, p-MeOCh 6H 4, p-ClC 6H 4, p-O 2NC 6H 4) in high yield.

Studies on Nitrile Salts. II. A Facile One-step Synthesis of the Pyrimidine Nucleus

Abstract The reaction of N-(α-chloroalkenyl)alkylamidine hydrochlorides (1) with phosgene was studied. The amidine hydrochlorides (1a—h) which were prepared from nitriles with more than two α-hydrogens reacted with phosgene at 100—105°C to give good yields of 4,6-dichloro-2,5-disubstituted-pyrimidines (3a—h). The amidine hydrochlorides (1j—t), which were obtained from nitriles with only one α-hydrogen, afforded 2-alkylidene-4,6-dichloro-5,5-disubstituted-2,5-dihydropyrimidines (5j—t) in good yields. The amidine hydrochloride 1i, however, gave 2-dichloromethylidene-2,5-dihydro-5,5,6-trichloro-4(3H)-pyrimidinone (4i) under comparable conditions.