Furo pyrimidines

The use of a pyrimidine precursor continues to be the more popular approach to furo pyrimidines. The one-pot three-component condensation reactions of alkyl or aryl isocyanides with A[A -dimethylbarbituric acid in the presence of terephthaldialdehyde proceeded spontaneously at room temperature in DMF to give good yields of the corresponding l,4-bis(6-alkyl or arylamino-1,3-dimethylfurano[2,3-4]pyrimidin-2,4(l//,3//)-dione-5-yl)benzenes <2006BMCL3697>. 

Pyrimidines with an oxygen function at C-5 represent the most efficient precursors to furo[3,2-rf]pyrimidines. The formation of 5-propynyloxypyrimidines (240) allows cyclization to furo-pyrimidines (Equation (81)) (241). Treatment of compound (240 R = H) with sodium methoxide in warm DMSO gives the derivative (241 R = Me, R1 = H), whilst the methyl analogue (240 R = Me) undergoes thermal cyclization in DMSO to yield compound (241 R = R1 = Me). A parallel chemistry is described for the sulfur analogues <89JHC1851>. 

Furo[2,3-amino-synthesis, 4, 986 Furo[3,4-d]pyrimidinedione synthesis, 4, 987 Furopyrimidines, 4, 986 Furo[2,3-d]pyrimidines synthesis, 4, 986 Furo[3,2-d]pyrimidines synthesis, 4, 987 Furo[3,2- 6]pyrone synthesis, 4, 994 Furo[3,2-c]pyrone synthesis, 4, 993 Furo[3,2-6]pyrrole, hexahydro-biological activity, 6, 1024 1 H-Furo[3,4-6]pyrrole-2,3-dione, 4,6a-diphenyl-6-(phenylimino)-6,6a-dihydro-synthesis, 6, 1004 Furopyrroles... 

Chemical Name 2,3,3a,9a.Tetrahydro.3.hydroxy.6.imino.6H.furo[2, 3 4,5]oxazolo[3,2.a]. pyrimidine.2.methanol... 

Besides furo[2,3-d]pyrimidines, 6-substituted 5H-pyrrolo[2,3-h]pyrazines have also been obtained in a microwave-promoted one-pot process starting from N-mesyl protected 2-amino-3-chloropyrazine (Scheme 60) [74]. The... 

Routes have been developed to furo[3,2-e][l,2,4]triazolo[4,3-c]pyriniidmes 67 and furo [3,2-e]tetrazolo[l,5-c]pyrimidines 68 which are shown in Scheme 10 <96JHC659>. 

N- and O-Substituted terpenyl pyrimidines <05EJM552> as well as dihydropyrido[2,3-rf]-pyrimidines <05BMC6678> were prepared as antileishmanial agents. 5-Alkynyl- and 6-alkyl-furo[2,3-rf]pyrimidine acyclic nucleosides <05BMC1239>, acyclic furo- and... 

The Sonogashira adducts of halopyrimidines with pendant functional groups are good precursors for synthesizing condensed heteroaromatic compounds. Yamanaka s group prepared four different condensed heteroaromatics from further manipulations of such Sonogashira adducts. Those four condensed heteroaromatics are 5-oxo-7-pyrido[4,3- pyrimidine 88 [62], furo[2,3-... 

Tu SJ, Zhang Y, Jiang H, Jiang B, Zhang JY, JiaRH, Shi F (2007) A simple synthesis of furo 3, 4 5,6 pyrido 2,3-d pyrimidine derivatives through multicomponent reactions in water. Eur J Org Chem 1522-1528... 

In recent years, there has been a greater interest in joining certain heterocyclic systems to [60]-fullerene with pyrimidine-fused 3-sulfolenes as one such case. Three derivatives have been examined in membrane model environments and the aggregation of these derivatives has been studied <2000J(P2)301>. Similar studies have been carried out on furo[2,3- ]pyrimidines <1996JST(385)55>. 

Another example of the simultaneous formation of both the pyrrolo and furo compounds has been observed. Nearly identical yields of 102c and 103b were isolated <2005JME5329>. Nonetheless, other 6-substituted derivatives of pyrrolo[2,3- pyrimidines have been prepared without complication, for example, 102d <2001JHC349> and a variety of arylmethyl compounds, illustrated by 102e <2003BMC5155>. 

An alternative, but effective, method for preparing furo[2,3-r/ pyrimidines with the potential for polysubstitution in the furan ring is shown in Equation (108). Here -dimethylbarbituric acid 299 is treated with a variety of alkenes in MeCN containing cerium(iv) ammonium nitrate to produce 300 with complete regioselectivity (Equation 108) <2000SC4277>. 

Finally, a one-pot, three-component condensation reaction in water provides an efficient procedure for the synthesis of furo[2,3-r/ pyrimidine-2,4(1/7,3//)-diones 303 (Scheme 26). A, A -Dimethylbarbituric acid 301 and 4-nitrobenzaldehyde 302 are reacted with a series of isocyanides to give good yields of the 6-amino products 303 <2002TL9151, 2005SC535>. 

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