Multicomponent Hantzsch cyclocondensation as a route to highly functionalized 2- and 4-dihydropyridylalanines, 2- and 4-pyridylalanines, and their N-oxides: preparation via a polymer-assisted solution-phase approach
作者:Alessandro Dondoni、Alessandro Massi、Erik Minghini、Valerio Bertolasi
DOI:10.1016/j.tet.2004.01.011
日期:2004.3
incorporated into a tripeptide by coupling with (S)-phenylalanine. In a similar way tetrasubstituted β-(2-dihydropyridyl)alanine, β-(2-pyridyl)alanine and β-(1-oxido-2-pyridyl)alanine were prepared via Hantzsch cyclocondensation reaction using benzaldehyde, aminocrotonate, and acetoacetate carrying the N-Boc-O-benzyl glycinate moiety. It was shown that the work up of the reaction mixtures derived from the cyclocondensation
通过一锅式热Hantzsch型环缩合反应,已经开发出了一种改进且有效的进入高度官能化的β-(2-吡啶基)-和β-(4-吡啶基)丙氨酸以及相应的1,4-二氢和N-氧化物衍生物的方法。醛-酮酸酯-烯胺系统,其中一种试剂(醛或酮酸酯)带有未掩盖但受保护的手性甘氨酰部分。因此,将N- Boc - O-苄基天冬氨酸β-醛,乙酰乙酸酯和氨基巴豆酸酯偶联,得到四取代的β-(4-二氢吡啶基)丙氨酸(75%收率)。这些产物之一几乎被定量转化为β-(4-吡啶基)丙氨酸衍生物,后者被氧化成相应的N-氧化物。通过与(S)-苯丙氨酸偶合,将这些对映体纯的(Mosher酰胺分析)杂环α-氨基酸中的每一个掺入三肽中。以类似的方式,通过苯并甲醛,氨基巴豆酸酯和乙酰乙酸酯与苯甲醛一起经Hantzsch环缩合反应制备四取代的β-(2-二氢吡啶基)丙氨酸,β-(2-吡啶基)丙氨酸和β-(1-氧化-2-吡啶基)丙氨酸。N- Boc-