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Synthesis, crystal structure determination, and spectroscopic analyses of 1-chloro-2-(2,6-diisopropylphenyl)-4,4-dimethyl-2-azaspiro[5.5]undecane-3,5-dione: an unyielding precursor to a cyclic (alkyl)(amido)carbene
Acta Crystallographica Section C ( IF 0.7 ) Pub Date : 2021-06-25 , DOI: 10.1107/s2053229621006173
Todd W Hudnall 1 , Eric W Reinheimer 2 , Christopher L Dorsey 1
Affiliation  

The synthesis, single-crystal X-ray structure, and 1H and 13C NMR spectrocopic analyses of an unyielding precursor molecule to a cyclic (alkyl)(amido)carbene, 1-chloro-2-(2,6-diisopropylphenyl)-4,4-dimethyl-2-azaspiro[5.5]undecane-3,5-dione, C24H34ClNO2 (1), is reported. Despite the use of several bases, 1 could not be deprotonated to afford the corresponding carbene. The crystal structure of 1 was compared to the crystal structures of two structurally similar HCl adducts of stable carbenes (compounds 4 and 5), which revealed no significant differences in the geometries about the `carbene' C atoms. To better understand the reactivity differences observed for 1 when compared to 4 and 5, modified percent buried volume (%Vbur) calculations were performed. These calculations revealed that the H atom bound to the carbene C atom is the most sterically hindered in compound 1 when compared to 4 and 5 (%Vbur = 84.9, 81.3, and 79.3% for 1, 4, and 5, respectively). Finally, close inspection of the quadrant-specific %Vbur values indicated that the approach of a deprotonating base to the H atom bound to the carbene C atom is significantly blocked in 1 (69.9%) when compared to 4 and 5 (50.4 and 56.5%, respectively).

中文翻译:

1-氯-2-(2,6-二异丙基苯基)-4,4-二甲基-2-氮杂螺[5.5]十一烷-3,5-二酮的合成、晶体结构测定和光谱分析:环状化合物的不屈服前体(烷基)(酰氨基)卡宾

环状(烷基)(酰胺基)卡宾、1-氯-2-(2,6-二异丙基苯基)-的不屈服前体分子的合成、单晶 X 射线结构以及1 H 和13 C NMR 光谱分析报道了4,4-二甲基-2-氮杂螺[5.5]十一烷-3,5-二酮,C 24 H 34 ClNO 2 ( 1 )。尽管使用了几种碱基,但1无法去质子化以提供相应的卡宾。将1的晶体结构与两种结构相似的稳定卡宾的 HCl 加合物(化合物45),这表明“卡宾”C 原子的几何形状没有显着差异。为了更好地理解145相比观察到的反应性差异,进行了修正的埋藏体积百分比 (% V bur ) 计算。这些计算表明,结合到卡宾的C原子的氢原子是最位在化合物受阻1时相比,45(%V BUR  = 84.9,81.3,和79.3%为14,和5,分别地)。最后,仔细检查象限特定的 % Vbur值表明,与45(分别为 50.4 和 56.5% )相比,去质子化碱接近与卡宾 C 原子结合的 H 原子在1(69.9%)中被显着阻止。
更新日期:2021-07-04
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