Efficient routes to pyranosidic homologated conjugated enals and dienes from monosaccharides
作者:J. Cristóbal López、Eric Lameignère、Catherine Burnouf、María de los Angeles Laborde、Alberto A. Ghini、Alain Olesker、Gabor Lukacs
DOI:10.1016/s0040-4020(01)87245-8
日期:1993.8
have been designed in the context of the preparation of useful chiral building blocks from monosaccharides. Addition of vinylmagnesium bromide onto ulose , followed by acetal ring opening; benzoate protection at C-4 and C-6; and dehydration of the tertiary hydroxyl group, mediated by thionyl chloride, reveals to be a straigthforward route to diene . Analogous dehydration on conformationally rigid was
在由单糖制备有用的手性结构单元的背景下,已经设计了三种用于获得B型和D型吡喃二烯的新方法和同系的共轭烯醛A。将乙烯基溴化镁加到蔗糖上,然后缩醛开环;C-4和C-6的苯甲酸酯保护; 由亚硫酰氯介导的叔羟基的脱水反应是二烯的直接反应。构象刚性上的类似脱水不是区域选择性的,并以1:1的比例提供异构二烯。在锁定的2,3-脱水吡喃糖上添加2-lithio-1,3二噻烷和接着S的散开,S-缩醛部分有效地导致了同系化α-enals ,,,和,并因此二烯,,并通过维悌希亚甲基化。最后α-烷氧基乙烯基醚,制备或者通过α -烷氧基- uloses的Wittig-Horner反应,或通过杂共轭enals,在良好的给予优异的产率pyranosidicα-enals的Diels-Alder反应,,,,和与治疗吡啶中的盐酸吡啶鎓盐或乙酸-水(4:1)的混合物。