Synthesis of indazole-N-oxides via the 1,7-electrocyclization of azomethine ylides
作者:Miklós Nyerges、Andrea Virányi、Weimin Zhang、Paul W. Groundwater、Gábor Blaskó、László Tőke
DOI:10.1016/j.tet.2004.08.026
日期:2004.10
The first examples of the 1,7-electrocyclization of azomethine ylides onto a nitro group, to give benz-1,2,6-oxadiazepine intermediates are reported. Subsequent ring contraction results in the formation of indazole-N-oxides. (C) 2004 Elsevier Ltd. All rights reserved.
Synthesis of indazole- N -oxides via the 1,7-electrocyclisation of azomethine ylides
作者:Miklós Nyerges、Imre Fejes、Andrea Virányi、Paul W Groundwater、László Tőke
DOI:10.1016/s0040-4039(01)00892-9
日期:2001.7
The first example of the 1,7-electrocyclisation of a non-stabilised azomethine ylide, e.g. 2, onto a nitro group, to give a 1,2,6-oxadiazepine intermediate, e.g. 4, is reported. Subsequent ring contraction results in the formation of the indazole-N-oxides 5, 12, and 14. (C) 2001 Elsevier Science Ltd. All rights reserved.
Synthesis of 5-Aryloxazolidines via 1,3-Dipolar Cycloaddition Reaction of a Non-Stabilized Azomethine Ylide with Aromatic Aldehydes
作者:John H. Ryan、Nadia Spiccia、Leon S.-M. Wong、Andrew B. Holmes
DOI:10.1071/ch07282
日期:——
The 1,3-dipolarcycloadditionreaction of a non-stabilized azomethine ylide 4a, formed in situ from N-(methoxymethyl)-N-(trimethylsilylmethyl)benzylamine 5 and a catalytic amount of trifluoroacetic acid, with aromatic aldehydes 3 gives rise to N-benzyl-5-aryloxazolidines 1. Under these conditions, 4-hydroxybenzaldehyde 3p undergoes two-fold addition of azomethine ylide 4a to afford bis adduct 11.
An efficient two-step synthesis of 1-aryl-2-dimethylaminoethanols 4 is described, consisting of oxazolidine 3 generation from the cycloaddition of an azomethine ylide to an aldehyde, followed by reductive ring-opening.