Pyrrolo pyrimidine 5-oxides

In an analogous fashion, pyrrolo[l,2-c]pyrimidine (66), the preparation of which was discussed in Section 6.2.2.1, was converted to the corresponding quatemized salt 67 <99JOC7788>. This heterocycle was shown to undergo 1,3-dipolar additions with a variety of dipolarophiles such as aUcynes to produce 68 after oxidation with DDQ. 

Finally, an unusual approach to pyrrolo[2,3- pyrimidines is seen in Equation (40). The dimethyluracil 113 is presumed to form the A -oxide at the exocyclic nitrogen atom. This then undergoes a [2,3]-sigmatropic rearrangement followed by a [3,3]-sigmatropic rearrangement, tautomerization, and cyclization to give 114 <200581164>. 

Cyclization of 6-acetylenic derivatives constitutes yet another approach to pyrrolo[3,2-.7 pyrimidines. A series of 6-substituted acetylenes 209, prepared by alkynylation of the chloropyrimidine, undergo cyclization to the A -oxides 210 when heated briefly in pyridine (Equation 72) <2003SL1151, 2004CHE1335>. 

Azine A-oxides and azine A-imides undergo a deep ring transformation on interaction with various dipolarophiles. Thus, fervenulin-4-oxides (423) react with DMAD to afford derivatives of pyrrolo[3,2-first step of the reaction is assumed to involve the formation of cycloaddition products (424) which transform by subsequent multi-stage process into (425) (79JOC3830). 

Pyrimidin 6-Amino-2,4-dioxo-3-phenyl-l,2,3,4-tetrahydro- E15/2, 2228 [ —R—OH(Cyclokond.)] lH- 6-Nitro-2,3-dihydro- IV/la, 182 Quinolin 4-Hydrazino-6,7-methylen-dioxy- E16a, 700 (Cl - NH-NH2) Quinolin-l-oxid 2-Amino-3-aminocarbonyl- E7a, 504 [2-N02 - Ar -CH = C(CN) -CO —NH2/Pt]... 

A tandem aza-Wittig/heterocumulene-mediated annulation route was developed for the efficient production of 6,7,8,9-tetrahydro-benzothieno[2,3-r/]-l,2,4-triazolo[l,5-a]pyrimidin-10(3F/)-ones <05S1601>, and an amine oxide rearrangement was key to the regioselective preparation of pyrrolo[2,3-J]pyrimidines <0581164>. Hexahydro-2-phenacylidene-pyrimidines gave -lactam fused 8-aroyl-2,3,4,5-tetrahydro-7-hydroxy-6//-pyrrolo[l,2-a]py-rimidine-6-ones when treated with (COCl), in the presence of NaH <05IJH87>, and methyl... 

The quinazolinepropionitrile 3-oxides 125 were cyclized with alkali metal hydroxide in aqueous alcohol to the pyrrolo[l,2-a]pyrimidine 4-oxides 126. ... 

The reaction of the pyrimidotriazine 4-oxide (315) with acetylenic esters results in ring contraction to give the pyrrolo [3,2-d] pyrimidine (318). 

Lead tetraacetate Oxidative and reductive pyrrolo[l,2-c]pyrimidine ring opening... 

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