- Oxidative rearrangement and cyclisation of N-substituted amidines using iodine(III) reagents and the influence of leaving group on mode of reaction
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The products of reaction of N-substituted amidines 5 with hypervalent iodine reagents such as (diacetoxyiodo)benzene (DAIB), bis(trifluoroacetoxy)iodobenzene (BFIB) and [methoxy(tosyloxy)-iodo]benzene (MTIB) are determined by the reagent, the amidine substituents and the reaction temperature. C-Alkyl-N-arylamidines 5a-d cyclise in high yield giving benzimidazoles 6 but C,N-dialkyl- and C,N-diaryl-amidines 5e-l rearrange to give products derived from an intermediate carbodiimide. Use of N2-phenylfuran-2-carboximidamide 5j leads to N-(2-furyl)acetamide 15 in good yield, illustrating a convenient route to stable derivatives of highly unstable 2-aminofuran. The rearrangement of C,N-diarylamidines on reaction with DAIB contrasts with the observed formation of benzimidazole when the same precursors are treated with lead tetraacetate (LTA). Evidence is presented to support the view that the mode of reaction is determined by the nature of the leaving group in an imide intermediate 19: very good leaving groups [e.g. PhI, N2, AgCl and PhSO2O- (aq.)] appear to favour rearrangement whereas poorer leaving groups [e.g. Cl-, Me2S, Me3N and PhSO2O- (non-aq.)] favour cyclo-α-elimination.
- Ramsden, Christopher A.,Rose, Helen L.
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p. 2319 - 2327
(2007/10/03)
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- Rearrangement and cyclo-α-elimination of N-substituted amidines using (acetoxyiodo)benzene
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The products of reaction of N-substituetd amidines with (diacetoxyiodo)benzene are determined by the nature of the amidine substituents and the reaction temperature: rearrangement of N2-phenylfuran-2-carboximidamide provides a convenient route to N-(2-furyl)acetamide, whereas N-phenyl C-alkyl formimidamides cyclise to give benzimidazoles in good yield.
- Ramsden, Christopher A.,Rose, Helen L.
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p. 615 - 618
(2007/10/02)
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- A mild approach to N-acylformamidines and C-acylamidines by the facile reduction of carbodiimides with pentacoordinated silicon hydrides
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N1-acyl-, N1-aryl-N3-arylformamidines 4 and N1,N2-dialkyl C-acylamidines 6 result from the acylation of the N1-silylformamidines 2a and C-silyl amidines 2b, c respectively. The latter are o
- Corriu,Lanneau,Perrot-Petta
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p. 954 - 958
(2007/10/02)
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- Mild Acetylation of Amides, Thiamides, Ureas, and Thioureas Using Methyl Bis(1-naphthyl)bismuthinate in Acetic Acid
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Amides, thioamides, ureas, and thioureas were N-acetylated in good yield with acetic acid in the presence of methyl bis(1-naphthyl)bismuthinate at room tempereature.
- Ogawa, Takuji,Miyazaki, Kikuko,Suzuki, Hitomi
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p. 1651 - 1654
(2007/10/02)
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