A New Pyridine-2,6-bis(oxazoline) for Efficient and Flexible Lanthanide-Based Catalysts of Enantioselective Reactions with 3-Alkenoyl-2-oxazolidinones
作者:Giovanni Desimoni、Giuseppe Faita、Matilde Guala、Anna Laurenti、Mariella Mella
DOI:10.1002/chem.200401213
日期:2005.6.20
A new pyridine-2,6-bis(oxazoline) (4) has been easily synthesised from the reaction of (1S,2S)-2-amino-1-phenylpropane-1,3-diol (1) and dimethyl pyridine-2,6-dicarboximidate (2), followed by TIPS (TIPS=triisopropylsilyl) protection of the 4'-CH2OH group. The catalysts derived from 4 and eight lanthanide(III) triflates have been tested over three reactions involving 3-acryloyl- and 3-crotonoyloxazolidinones
从(1S,2S)-2-氨基-1-苯基丙烷-1,3-二醇(1)与二甲基吡啶2的反应轻松合成新的吡啶2,6-双(恶唑啉)(4) ,6-二羧酸亚氨基酯(2),然后对4'-CH 2 OH基团进行TIPS(TIPS =三异丙基甲硅烷基)保护。在涉及3-丙烯酰基和3-巴豆酰恶唑烷酮(5 a,b)的三个反应中测试了衍生自4和8个三氟甲磺酸镧系元素的催化剂(5 a,b):与环戊二烯的Diels-Alder(DA)反应,1,3-用二苯基硝酮进行偶极环加成反应,用2-三甲基甲硅烷基氧基呋喃进行Mukaiyama-Michael反应。几个反应表现出非常好的对映选择性(ee> 90%),而相反的对映异构体可以很容易地通过改变阳离子来获得。配体的这一特定特征可以在5 a的DA反应中得到理解,因为催化剂[Sc(III)4]给出了具有99%ee的加合物(2'S)-9a,而催化剂[Y(III)4]得到了具有95%ee的相