Scope and limitations in sulfur ylide mediated catalytic asymmetric aziridination of imines: use of phenyldiazomethane, diazoesters and diazoacetamides
Scope and limitations in sulfur ylide mediated catalytic asymmetric aziridination of imines: use of phenyldiazomethane, diazoesters and diazoacetamides
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DOI：
10.1039/b102578n
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发表时间：
2001-01-01
期刊：
影响因子：
--
通讯作者：
Fieldhouse, R
中科院分区：
文献类型：
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作者：
Aggarwal, VK;Ferrara, M;Fieldhouse, R
研究了在金属盐和硫化物的催化量下，重氮化合物催化亚胺氮杂环丙烷的反应。合成了一系列含苯甲醛吸电子基团的亚胺(N-ts，N-SO2CH2CH2SiMe3(SES)，N-P(O)Ph-2，N-CO2Bn，N-CO2(CH2)(2)SiMe3，N-CO2C(CH3)(2)CCl3)，并在Me2S和苯基重氮甲烷的氮化反应中进行了表征。所有亚胺的产率都很高，但非对映选择性差异很大(3：1-->；10：1)。用化学计量的硫化物对一系列N-SES亚胺进行了测试，芳香族和脂肪族亚胺的产率都很高。这些亚胺随后被化学计量和亚化学计量负载对映体纯的1，3-氧杂环己烷3与Rh-2(OAc)(4)和与铜(Acac)(2)。Rh-2(OAc)(4)具有较好的产率和较高的对映体选择性(89-95%)，而Cu(Acac)(2)对映体过量略有减少(85-95%)，特别是在使用亚化学计量硫化物时。同样的硫化物也与亚胺氮上的一系列电子吸引基团一起进行了测试，在所有情况下都保持了良好的产率和高的对映选择性。氨基甲酸酯类化合物的非对映选择性得到了改善。将氮杂环化反应过程扩展到包括重氮酯和重氮乙酰胺以及一系列N-ts亚胺，并再次获得了良好的产率，尽管非对映选择性因所用重氮化合物的不同而不同。虽然1，3-氧杂环己烷3不能与这些更稳定的重氮化合物结合，但(R，R)-2，5-二甲基硫杂环己烷5被发现是一种合适的手性催化剂，具有中等的对映和非对映选择性。为非对映选择性和对映选择性的起源提供了理论依据。
Imine aziridination using diazo-compounds and catalytic quantities of metal salts and sulfides has been investigated. A range of imines derived from benzaldehyde bearing electron-withdrawing groups (N-Ts, N-SO2CH2CH2SiMe3 (SES), N-P(O)Ph-2, N-CO2Bn, N-CO2But, N-CO2(CH2)(2)SiMe3, N-CO2C(CH3)(2)CCl3) were prepared and tested in the aziridination process using Me2S and phenyldiazomethane. High yields were obtained with all imines but diastereoselectivity varied considerably (3 : 1--> 10 : 1). A range of N-SES imines were tested with stoichiometric amounts of sulfides and high yields were obtained with both aromatic and aliphatic imines. These imines were subsequently testedwith stoichiometric and sub-stoichiometric loadings of enantiomerically pure 1,3-oxathiane 3 with Rh-2(OAc)(4) and with Cu(acac)(2). Good yields and high enantioselectivities (89-95%) were observed with Rh-2(OAc)(4), although a small reduction in enantiomeric excess was observed with Cu(acac)(2) (85-95%) especially when sub-stoichiometric amounts of sulfide were employed. The same sulfide was also tested with a range of electron-withdrawing groups on the imine nitrogen and in all cases good yields and high enantioselectivities were maintained. Improved diastereoselectivity was observed with carbamate groups.The aziridination process was extended to include diazoester and diazoacetamides with a range of N-Ts imines, and again good yields were obtained although diastereoselectivity varied according to the diazo-compound employed. Although the 1,3-oxathiane 3 could not be employed with these more stable diazo-compounds, (R,R)-2,5-dimethylthiolane 5 was found to be a suitable chiral catalyst and gave moderate enantio- and diastereoselectivities. Rationales for the origin of the diastereoselectivity and enantioselectivity are provided.