β-Alkoxy-γ-amino Aldehydes by Internal Redox Ring Cleavages of Carbohydrate-Derived Enantiopure 1,2-Oxazines and Preparation of Heterocycles with Aminopolyol Side Chain
作者:Hans-Ulrich Reissig、Ahmed Al-Harrasi、Léa Bouché、Reinhold Zimmer
DOI:10.1055/s-0030-1258326
日期:2011.1
N-Methylation of syn- or anti-configured 3,6-dihydro-2H-1,2-oxazines and subsequent treatment with triethylamine smoothly provided enantiopure α,β-unsaturated β-alkoxy-γ-amino aldehydes bearing different protected diol, triol, or tetrol side chains in good to excellent yields. The N-O bond cleavage occurs under mild conditions and involves an internal redox process. The method is also applicable to tetrahydro-2H-1,2-oxazines, which either lead to 4-amino ketose or aldose derivatives (d-sorbose or d-idose configuration). The equivalency of the generated β-alkoxyenal moiety with 1,3-dicarbonyl compounds could be demonstrated by condensation reactions with hydrazine or 2-aminoimidazole derivatives providing a series of new pyrazole or imidazo[1,2-a]pyrimidine derivatives with stereodefined and protected aminopolyol side chains.
N-甲基化syn-或anti-构型的3,6-二氢-2H-1,2-恶嗪,然后与三乙胺处理,顺利提供了具有不同保护二醇、三醇或四醇侧链的高至优异收率的立体纯α,β-不饱和β-烷氧基-γ-氨基醛。N-O键在温和条件下断裂,涉及内部氧化还原过程。该方法也适用于四氢-2H-1,2-恶嗪,它们要么导致4-氨基酮糖或醛糖衍生物(d-山梨糖醇或d-艾杜糖醇构型)。生成的β-烷氧基烯醛部分与1,3-二羰基化合物的等价性可以通过与肼或2-氨基咪唑衍生物的缩合反应证明,提供了一系列具有立体定义和保护氨基多醇侧链的新型吡唑或咪唑并[1,2-a]嘧啶衍生物。