Pyrimidine 2-chloro-4,6-dimethyl

The ease of displacing a chloro, bromo or iodo substituent in comparable pyrimidines by aminolysis is disappointingly similar. Using 2-halogeno-4,6-dimethyl- and 4-halogeno-... 

In view of the high price and other difficulties associated with the use of phosphoryl bromide, the transhalogenation of 2-chloro- and 2-chloro-4,6-dimethyl-pyrimidine (919) by treatment with inexpensive phosphorus tribromide to give their bromo analogues in >50% yield, assumes potential importance as a general method (67JCS(C)1204). 

Chloro-3-ethoxy-2-methyl-2//-pyrazolo[4,3-reacted with the sodium salt of dimethyl malonate in DMF to give (pyrazolo[4,3-c/]pyrimidin-7-yl)malonate (499) [88JAP(K)246377]. 

Chloro-2,3-dihydro-7-(hydroxymethyl)-3,3-dimethyl-5//-oxazolo[3,2-a]pyrimidin-5-one, see Terbacil 6-Chloro-2,3-dihydro-7-methyl-3,3-dimethyl-5//-oxazo lo[3,2-a]pyrimidin-5-one, see Terbacil Chlorodihydroxybiphenyl, see TCDD... 

Plant The major degradation products of [2- C]terbacil identified in alfalfa using a mass spectrometer were (% of applied amount) 3-/er/-butyl-5-chloro-6-hydroxymethyluracil (11.9) and 6-chloro-2,3-dihydro-7-(hydroxymethyl)-3,3-dimethyl-5//-oxazolo[3,2-a]pyrimidin-5-one (41.2). Two additional compounds tentatively identified by TLC were 3-/er/-butyl-6-hydroxy-methyluracil and 6-chloro-2,3-dihydro-7-methyl-3,3-dimethyl-5//-oxazolo[3,2-a]pyrimidin-5-one (Rhodes, 1977). 

Pyrimidine annulation of 2-chloro-3-cyanopyridine 373 with guanidine in dimethyl sulfoxide (DMSO) at 130 °C afforded the diaminopyrido[2,3-,7 pyrimidine 374 (Equation 31) <2001H(55)1679>. 

Chloro, 3-bromo, 3-iodo, and 3-nitro derivatives of 5,7-dimethyl-pyrazolo[l,5-a]pyrimidine derivatives were prepared by chlorination, bromination, iodination, and nitration of 3-unsubstituted 5,7-dimethyl-pyrazolo[l,5-a]pyrimidines. Reaction with bromine and potassium thiocyanate gave a 3-thiocyanato derivative, which was converted into the mercapto derivative upon saponification. Nitrosation gives the 3-nitroso derivative and acylation with trifluoroacetic anhydride affords the trifluoroacetyl derivative (74JMC645 77JMC386). 

Dehydroxy-halogenalion of 89 using POCI3 led to dihalopyrimidine 92, which was subsequently coupled with phenylacetylene to give 4-chloro-5-alkynylpyrimidine 93 [63, 64]. Subsequent treatment of 93 with sodium hydrosulfide in refluxing ethanol gave 2,4-dimethyl-6-phenylthieno[2,3-d]pyrimidine (94). 

Pyrimidin-4-amine, N-butyl-2,6-dimethyl-synthesis, 3, 130 Pyrimidin-4-amine, 6-chloro-thiolysis, 3, 101... 

Heating the thiazolo[5,4-d]pyrimidine obtained by triethylamine catalysed condensation of 6-chloro-l,3-dimethyl-5-nitrouracil with methyl thioglycolate with an equimolar amount of DMAD in 5% aqueous methanol gives the pyrrolo[3,2-d]pyrimidine 1 in 71% yield. 

Sakamoto et al. (82CPB2417) synthesized 4,6-dimethyl-2-phenylthieno-[2,3-d]pyrimidine 96 by reacting 4-chloro-2,6-dimethyl-5-phenylethynylpyr-imidine 95 with sodium hydrosulfide in boiling ethanol. In a similar manner, 4-chloro-5-(trimethylsilylethynyl)pyrimidines 97 were converted into thieno[2,3-d]pyrimidines 98 (86CPB2719 89YZ642). 

Chloro-6,8-dimethyl-l,7-naphthyridine (22) underwent ring fission by hydrazine to give 2,6-dimethyl-4-(pyrazol-3-yl)-3-pyridinamine (23) (H2NNH2 H20, 150°C, sealed, 5 h 65%), confirmed in structure by cycliza-tion with triethyl orthoformate to 7,9-dimethyllpyrazolo 1,5-c pyrido[4,3-e] pyrimidine (24) (reactants, EtOH, reflux, 3 h 60%).1098... 

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