Chemo-, Regio-, and Stereoselective Diels–Alder Reaction of Ambident Dienophilic Monothiomaleimide
作者:Yoshinao Tamaru、Hiroto Harayama、Hiroya Sakata、Hironobu Konishi、Keigo Fugami、Masanari Kimura、Shuji Tanaka、Toshiya Okajima、Yoshimasa Fukazawa
DOI:10.1002/jlac.199719970520
日期:1997.5
vs. CC chemoselectivity in favor of CS, while N-p-anisyl (11b) and N-benzyl (11c) derivatives display quite the reverse reactivity and selectivity. N-Phenylmonothiocitraconimide (11d) serves as a CS specific dienophile and reacts with dienes to furnish ortho,endo adducts 12 with excellent regio- and stereoselectivities (100% ortho,endo). Both hard (BF3 · OEt2, TiCl4) and soft (CuBr · SMe2) Lewis acids
N-芳基单硫代马来酰亚胺的CS和CC官能团在给电子和吸电子二烯的环境温度下都容易发生[4 + 2]环加成反应。N-芳基单硫马来酰亚胺的CS基团通常比CC基团更具反应性,特别是对带有共轭基团和电子吸引基团的二烯,并提供具有完全区域选择性(100%邻位)的邻位,内位产物3和邻位,外位产物4的混合物并且具有高立体选择性(超过86%内切)。另一方面,CC组显示出较高的立体选择性(100%内标),但区域选择性低,以1:1至6:1的比例提供邻位,内位加合物5和间位,内位加合物6。与N-苯基单硫代马来酰亚胺相比(1)。NP -nitrophenylmonothiomaleimide(11A)是更具反应性的,并显示有利于CS的较高CS与CC化学选择性,而Np个-anisyl(11B)和ñ -苄基(图11C)显示的衍生物相当的反向反应性和选择性。N-苯基单硫代西con康酰亚胺(11d)作为CS特定亲二烯体发