Silica-water reaction media: its application to the formation and ring opening of aziridines.
Silica-water reaction media: its application to the formation and ring opening of aziridines.
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DOI：
10.1002/anie.200352842
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发表时间：
2004-04
影响因子：
--
通讯作者：
S. Minakata;Daisuke Kano;Yoji Oderaotoshi;M. Komatsu
中科院分区：
文献类型：
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作者：
S. Minakata;Daisuke Kano;Yoji Oderaotoshi;M. Komatsu
近年来，对环境友好的有机化学过程的需求有所增加，从生态学的角度来看，在未来设计和实施新的合成方法时必须考虑这个问题。[1]水介质中的有机反应在实现更环境友好的合成转化方面一直受到相当大的关注。[2]另一方面，氮丙啶[3]是各种有机合成的有用合成中间体，并且它们经常作为生物活性化合物的重要亚结构存在。因此，开发氮丙啶的有效合成路线对于有机化学家来说是一项有吸引力的任务，因此，多种方法已被开发。[4]We最近报道了在水介质中通过添加相转移催化剂（PTC）使用氯胺-T（CT）[4k]由烯烃碘催化形成氮丙啶。[4l]由于CT的离子特性，使用PTC以允许在水介质中的反应是通用方法。基于硅胶的吸附性质，设计了一种在水中的替代潜在过程。虽然硅胶在有机合成中的应用已经得到了广泛的研究[5]，但据我们所知，它在水介质中的有机反应中的应用还没有得到开发。[6]二氧化硅作为水中的有机反应介质将是有效的，因为作为底物的有机分子预计将通过二氧化硅表面与有机分子之间的疏水相互作用吸附到二氧化硅上（图1）。本文报道了碘催化的烯烃氮杂环丙烷的合成，以及在硅-水体系中的开环反应，其中硅胶（Silicone gel，MCM-41）的使用显示了独特的结果。尽管在K2 CO 3和催化量的I2存在下苯乙烯与CT在水中的反应根本不进行，但向体系中加入硅胶导致产生所需的氮丙啶（表1）。例如，当苯乙烯（1.0 mmol）在二氧化硅存在下用CT（2.0 mmol）、K2 CO 3（2.0 mmol）和I2（10 mol%）处理时，
In recent years, the demand for environmentally benign organic-chemical processes has increased and this issue must be considered, from the ecological point of view, in the future design and implementation of new synthetic methodologies.[1] Organic reactions in aqueous media have been the subject of considerable attention in terms of achieving more environmentally friendly synthetic transformations.[2] On the other hand, aziridines [3] are useful synthetic intermediates for a variety of organic syntheses and they are frequently present as important substructures of biologically active compounds. Thus, the development of an efficient synthetic route to aziridines represents an attractive task for organic chemists and, as a result, a variety of methodologies have been exploited.[4]We recently reported on the iodine-catalyzed formation of aziridines from olefins by using chloramine-T (CT)[4k] in aqueous media by the addition of a phase-transfer catalyst (PTC).[4l] The use of PTC to permit the reaction in aqueous media is a general method because of the ionic character of CT. An alternative potential process in water was devised based on the adsorptive nature of silica gel. Although the application of silica gel to organic synthesis has been widely investigated,[5] to the best of our knowledge its use in organic reactions in aqueous media has not been exploited.[6] Silica would be effective as organic reaction media in water because the organic molecule as a substrate would be expected to be adsorbed to the silica by hydrophobic interactions between the surface of the silica and the organic molecule (Figure 1). Herein we report on the iodine-catalyzed formation of aziridines from olefins by using CT and the ring opening of the resulting product in a silica–water system, in which the use of silica (silica gel or MCM-41) showed unique results. Although the reaction of styrene with CT in the presence of K2CO3 and a catalytic amount of I2 in water did not proceed at all, the addition of silica gel to the system led to the production of the desired aziridine (Table 1). For example, when styrene (1.0 mmol) was treated with CT (2.0 mmol), K2CO3 (2.0 mmol), and I2 (10 mol%) in the presence of silica