Abbasov Mikail E, Hudson Brandi M, Kong Weixu, Tantillo Dean J, Romo Daniel
Department of Chemistry and Biochemistry, Baylor University, One Bear Place 97348, Waco, Texas 76798, USA.
Org Biomol Chem. 2017 Apr 11;15(15):3179-3183. doi: 10.1039/c6ob02738e.
α,β-Unsaturated acylammonium salts are useful dienophiles enabling highly enantioselective and stereodivergent Diels-Alder-initiated organocascades with furan-based dienes. Complex polycyclic systems can thus be obtained from readily prepared dienes, commodity acid chlorides, and a chiral isothiourea organocatalyst under mild conditions. We describe the use of furan-based dienes bearing pendant sulfonamides leading to the generation of oxa-bridged, trans-fused tricyclic γ-lactams. This process constitutes the first highly enantio- and diastereoselective, organocatalytic Diels-Alder cycloadditions with these typically problematic dienes due to their reversibility. Computational studies suggest that the high diastereoselectivity with these furan dienes may be due to a reversible Diels-Alder cycloaddition for the endo adducts. In addition, the utility of this methodology is demonstrated through a concise approach to a core structure with similarity to the natural product isatisine A and a nonpeptidyl ghrelin-receptor inverse agonist.
α,β-不饱和酰铵盐是有用的亲双烯体，能与基于呋喃的二烯发生高度对映选择性和立体发散性的狄尔斯-阿尔德引发的有机串联反应。因此，在温和条件下，复杂的多环体系可以由易于制备的二烯、市售的酰氯和手性异硫脲有机催化剂制得。我们描述了带有侧链磺酰胺的基于呋喃的二烯的使用，该二烯可导致生成氧桥连的反式稠合三环γ-内酰胺。由于其可逆性，该过程构成了首次与这些典型的有问题的二烯进行的高度对映选择性和非对映选择性的有机催化狄尔斯-阿尔德环加成反应。计算研究表明，与这些呋喃二烯的高非对映选择性可能是由于内型加合物的狄尔斯-阿尔德环加成反应具有可逆性。此外，通过一种简洁的方法制备了与天然产物异靛蓝A和非肽基胃饥饿素受体反向激动剂具有相似性的核心结构，证明了该方法的实用性。
