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

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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 (%V_bur) 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 (%V_bur = 84.9, 81.3, and 79.3% for 1, 4, and 5, respectively). Finally, close inspection of the quadrant-specific %V_bur 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4和5)，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1与4和5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，4和5（％V _BUR = 84.9，81.3，和79.3％为1，4，和5，分别地）。最后，仔细检查象限特定的 % V_bur值表明，与4和5（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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