E/Z equilibrium in tertiary amides. Part 2: N-acyl-N′-arylhexahydropyrimidines
作者:Juan Á. Bisceglia、Ma. Cruz Mollo、Liliana R. Orelli
DOI:10.1016/j.molstruc.2009.12.011
日期:2010.3
presented. Due to hindered rotation around the (O)C–N bond, tertiary amides 1 exist as a mixture of non-separable E/Z diastereoisomers, which show separate signals in the NMR spectra. For some selected derivatives, differential assignment of the 1 H resonances of the E/Z rotamers was made on the basis of the magnitude of ASIS (anisotropic solvent induced shifts) effects and confirmed by NOESY. The
摘要 介绍了一系列新型 N-酰基-N ' - 芳基六氢嘧啶 1 的 1 H 和 13 C NMR 光谱研究。由于围绕 (O)C-N 键的旋转受阻,叔酰胺 1 以不可分离的 E/Z 非对映异构体的混合物形式存在,其在 NMR 光谱中显示出单独的信号。对于某些选定的衍生物,E/Z 旋转异构体的 1 H 共振的差异分配是根据 ASIS(各向异性溶剂引起的位移)效应的大小进行的,并由 NOESY 确认。HSQC 和 HMBC 实验明确地归因于相应的 13 C 信号。使用 ab initio RHF/6-311G++ 方法对两个代表性成员进行了详细的构象研究。
1,n-Diamines. Part 3: Microwave-assisted synthesis of N-acyl-N′-arylhexahydropyrimidines and hexahydro-1,3-diazepines
作者:Juan Á. Bisceglia、Jimena E. Díaz、Romina A. Torres、Liliana R. Orelli
DOI:10.1016/j.tetlet.2011.07.131
日期:2011.10
In this Letter we present a method for the synthesis of N-acyl-N'-arylhexahydropyrimidines 1, by ring closure of N-acyl-N'-aryl-1,3-propanediamines 3 with formaldehyde. Cyclodehydrations were performed in aqueous medium under microwave irradiation, and led to high yields of the desired compounds in remarkably short reaction times. The method also allowed for the synthesis of hitherto unreported N-acyl-N'-arylhexahydro-1,3-diazepines 2. The acyclic tetramethylenic precursors 4 were synthesized by selective functionalization of N-arylputrescines. (C) 2011 Elsevier Ltd. All rights reserved.