Hackenberger Christian P R, Raabe Gerhard, Bolm Carsten
Institut für Organische Chemie der RWTH Aachen, Professor-Pirlet-Strasse 1, 52056 Aachen, Germany.
Chemistry. 2004 Jun 21;10(12):2942-52. doi: 10.1002/chem.200306016.
N-Acylated sulfoximines display unique chemical properties. Various derivatives have been synthesized and investigated by NMR and IR spectroscopy. The results of these studies suggest that the bond between the sulfoximine nitrogen atom and the carbonyl group has a less pronounced double-bond character than the corresponding bond in an amide. This assumption is supported by the first X-ray crystal structure of a sulfoximidoyl derivative. Ab initio calculations (MP2/6-311++G**) provide further insight into the electronic nature of the N-acyl fragment. Studies of the chemical behavior of N-acylated sulfoximines indicate the presence of a highly electrophilic carbonyl group. Thus, the N--C(O) bond can easily be cleaved under mild basic conditions, and the acidity of the hydrogen atoms alpha to the sulfoximine carbonyl group is high. As a consequence of the latter property, endo,endo-sulfoximidoyl norbornene derivatives readily isomerize to their endo,exo counterparts, and sulfoximine-containing pseudopeptides can easily epimerize at the stereogenic center next to the N--C(O) carbonyl group.
N-酰化磺胺肟具有独特的化学性质。已合成了各种衍生物，并通过核磁共振（NMR）和红外光谱（IR）进行了研究。这些研究结果表明，磺胺肟氮原子与羰基之间的键的双键特征不如酰胺中相应的键明显。这一假设得到了磺胺肟基衍生物的首个X射线晶体结构的支持。从头算计算（MP2/6-311++G**）进一步深入了解了N-酰基片段的电子性质。对N-酰化磺胺肟化学行为的研究表明存在一个高度亲电的羰基。因此，N-C（O）键在温和的碱性条件下很容易断裂，并且磺胺肟羰基α位氢原子的酸性很高。由于后一种性质，内型，内型-磺胺肟基降冰片烯衍生物很容易异构化为其外型，外型对应物，并且含磺胺肟的拟肽可以很容易地在N-C（O）羰基旁边的手性中心处发生差向异构化。
