Suga Hiroyuki, Adachi Yuki, Fujimoto Kouhei, Furihata Yasuhisa, Tsuchida Teruko, Kakehi Akikazu, Baba Toshihide
Department of Chemistry and Material Engineering, Faculty of Engineering, Shinshu University, Wakasato, Nagano 380-8553, Japan.
J Org Chem. 2009 Feb 6;74(3):1099-113. doi: 10.1021/jo802392c.
Asymmetric cycloaddition reactions between several nitrile oxides and 3-(2-alkenoyl)-2-oxazolidinones and 2-(2-alkenoyl)-3-pyrazolidinone derivatives were carried out in the presence of chiral binaphthyldiimine (BINIM)-Ni(II) complexes as catalysts. Using (R)-BINIM-4(3,5-xylyl)-2QN-Ni(II) complex (30 mol %), good regioselectivity (4-Me/5-Me = 85:15) along with high enantioselectivity (96% ee) of the 4-Me adduct were obtained for the reaction between isolable 2,4,6-trimethylbenzonitrile oxide and 3-crotonoyl-5,5-dimethyl-2-oxazolidinone. Substituted and unsubstituted benzonitrile oxides and aliphatic nitrile oxides, which were generated from the corresponding hydroximoyl chloride in the presence of MS 4A, were reacted with 3-crotonoyl-5,5-dimethyl-2-oxazolidinone, 5,5-dimethyl-3-(2-pentenoyl)-2-oxazolidinone, 5,5-dimethy-3-[3-(ethoxycarbonyl)propenoyl]-2-oxazolidinone, 1-benzyl-2-crotonoyl-5,5-dimethyl-3-pyrazolidinone, and 1-benzyl-2-[3-(ethoxycarbonyl)propenoyl]-5,5-dimethy-3-pyrazolidinone in the presence of (R)-BINIM-4Ph-2QN-Ni(II) or (R)-BINIM-4(3,5-xylyl)-2QN-Ni(II) complexes (10-30 mol %) as catalysts to give the corresponding cycloadducts in high yields, with high regioselectively (4-R/5-R = 85:15-99:1) and with moderate to high enantioselectivities (42-95% ee) of the 4-R adducts. Higher enantioselectivities and regioselectivities were obtained for the reactions using pyrazolidinone derivatives as the dipolarophiles. For the cycloadditions of 2-(2-alkenoyl)-1-benzyl-5,5-dimethyl-3-pyrazolidinones catalyzed by (R)-BINIM-4(3,5-xylyl)-2QN-Ni(II) complex (30 mol %), the enantioselectivity varied from 75% to 95% ee. The reactions between several nitrile oxides and 2-acryloyl-1-benzyl-5,5-dimethyl-3-pyrazolidinone in the presence of (R)-BINIM-4(3,5-xylyl)-2QN-Ni(II) complex (10 mol %) resulted in enantioselectivities (79-91% ee) that exceed those of previously reported enantioselective cycloadditions of acrylic acid derivatives. Furthermore, studies using a molecular modeling program using PM3 calculations were carried out to gain insight into the mechanisms of the asymmetric induction.
在手性联萘二亚胺（BINIM）-Ni（II）配合物作为催化剂的存在下，进行了几种腈氧化物与3-（2-烯丙酰基）-2-恶唑烷酮和2-（2-烯丙酰基）-3-吡唑烷酮衍生物之间的不对称环加成反应。使用（R）-BINIM-4（3,5-二甲基苯基）-2QN-Ni（II）配合物（30 mol%），对于可分离的2,4,6-三甲基苯腈氧化物与3-巴豆酰基-5,5-二甲基-2-恶唑烷酮之间的反应，4-Me加合物获得了良好的区域选择性（4-Me/5-Me = 85:15）以及高对映选择性（96% ee）。在MS 4A存在下由相应的偕肟酰氯生成的取代和未取代的苯腈氧化物以及脂肪族腈氧化物，与3-巴豆酰基-5,5-二甲基-2-恶唑烷酮、5,5-二甲基-3-（2-戊烯酰基）-2-恶唑烷酮、5,5-二甲基-3-[3-（乙氧羰基）丙烯酰基]-2-恶唑烷酮、1-苄基-2-巴豆酰基-5,5-二甲基-3-吡唑烷酮和1-苄基-2-[3-（乙氧羰基）丙烯酰基]-5,5-二甲基-3-吡唑烷酮在（R）-BINIM-4Ph-2QN-Ni（II）或（R）-BINIM-4（3,5-二甲基苯基）-2QN-Ni（II）配合物（10 - 30 mol%）作为催化剂的存在下反应，以高收率得到相应的环加成产物，4-R加合物具有高区域选择性（4-R/5-R = 85:15 - 99:1）以及中等至高对映选择性（42 - 95% ee）。使用吡唑烷酮衍生物作为亲偶极体的反应获得了更高的对映选择性和区域选择性。对于由（R）-BINIM-4（3,5-二甲基苯基）-2QN-Ni（II）配合物（30 mol%）催化的2-（2-烯丙酰基）-1-苄基-5,5-二甲基-3-吡唑烷酮的环加成反应，对映选择性在75%至95% ee之间变化。几种腈氧化物与2-丙烯酰基-1-苄基-5,5-二甲基-3-吡唑烷酮在（R）-BINIM-4（3,5-二甲基苯基）-2QN-Ni（II）配合物（10 mol%）存在下的反应产生的对映选择性（79 - 91% ee）超过了先前报道的丙烯酸衍生物对映选择性环加成反应的对映选择性。此外，使用PM3计算的分子建模程序进行了研究，以深入了解不对称诱导的机制。
