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。